Understanding Epilepsy

compiled by John G. Connor, M.Ac., L.Ac., edited by Barbara Connor, M.Ac., L.Ac., April 8, 2013

Table of Contents
Introduction
Excessive Glutamatergic Activity in Epilepsy
Oxidative Stress in Epilepsy Neurotransmitters, Signaling Pathways and Genes in Epilepsy
GABA, Neurosteroidogenesis and Epileptogenesis
Chronic Traumatic Encephalopathy
The Role of P2 Receptors and Microglial Cells in the Central Nervous System
Blood Tests in Epilepsy
Studies on Natural Compounds in Epilepsy

Introduction
Epilepsy is one of the most common and serious brain disorders in the world. It affects at least 50 million people worldwide. Approximately 100 million people will have at least one epileptic seizure during their lifetime. It causes serious physical, psychological, social, and economic consequences. The median prevalence of lifetime epilepsy for developed countries is 5.8 per 1,000 and 10.3 per 1,000 for developing countries. (Aguiar et al 2012)

Temporal lobe of epilepsy (TLE) is known to be the most common form of partial epilepsy and accounts for 60% of seizures. Depending on the seizure origin, TLE should be subdivided into mesial, lateral, and neocortical. Partial epilepsies are often associated with antecedent of brain injury, such as head trauma, stroke, or infection, and are therefore classified as “symptomatic”. (Salzmann & Malafosse 2012)

Temporal lobe epilepsy is typically associated with long-term memory dysfunction. The frontal lobes support high-level cognition comprising executive skills and working memory that is vital for daily life functioning. Deficits in these functions have been increasingly reported in TLE. Evidence from both the neuropsychological and neuroimaging literature suggests both executive function and working memory are compromised in the presence of TLE. (Stretton & Thompson 2012)

Temporal lobe epilepsy is the most prevalent form of complex partial seizures with specific temporal lobe related symptoms. Some studies showed that recurrent seizures affect all aspects of cognitive functioning including attention, language, praxis (practical application or exercise of a branch of learning), executive function intelligence, judgment, insight, and problem solving. However, the most important cognitive deficit in TLE is memory impairment. Damage to the mesial (toward the middle) structure of the temporal lobe, particularly the amygdale and hippocampus, has the main role in these memory difficulties. Other factors, including the long-term administration of antiepileptic drugs and seizure-related factors, i.e. age of onset, duration of the epilepsy, type of seizure, and psychosocial effects may also contribute to the cognitive decline over years. (Tavakoli et al 2011)

Family studies have shown that relatives of patients with epilepsy are at higher risk of suffering from seizures compared to relatives of controls. Moreover, relatives of patients with focal temporal EEG abnormalities have generally been found to have higher risks of EEG abnormalities which seem to be caused by an autosomal dominant gene. Therefore, various susceptibility genes and environmental factors are believed to be involved in the aetiology of TLE, which is considered to be a heterogeneous, polygenic, and complex disorder. However, few families with a monogenic type of TLE have been reported. To date, only a few chromosomal localisations and genes have been involved in TLE. (Salzmann & Malafosse 2012)

Neuronal excitability is homeostatically controlled between excitatory and inhibitory drives in the nervous system. Hyperexcitability, caused by the disruption of this delicate balance at the microcircuit level, may trigger the excessively synchronized electrical discharges of neurons in the brain which can manifest as epileptic seizures (Bertram, 2008). As a global health issue, epilepsy affects ~1% of the general population (World Health Organization, 2005).

Temporal lobe epilepsy, especially, is often pharmacologically refractory and is the most common type of acquired epilepsy that involves the hippocampus, entorhinal cortex, and amygdala. (Bertram, 2008). (Chang-Hoon Cho 2012)

Patients opt for alternative therapies because they may be dissatisfied with antiepileptic drugs due to their unpleasant side effects, the long duration of treatment, failure to achieve control of seizures, cultural beliefs and, in the case of women, because they wish to get pregnant. Surgical treatment may lead to physical and psychological sequelae and is an option only for a minority of patients. (Saxena & Nadkami 2011)The use of complementary and alternative medicine (CAM) has increased over the past two decades, and surveys have shown that up to 44% of patients with epilepsy are using some form of CAM treatment. (McElroy-Cox C 2009)

Excessive Glutamatergic Activity and Epilepsy 
A large number of animal models of epilepsy have clearly implicated a causal role for the glutamate-receptor family. Excessive stimulation of glutamatergic pathways, block of glutamate transporters or pharmacological manipulation resulting in glutamate-receptor activation can precipitate seizures. (Dingledine & McBain 1999)

Glutamate functions as a neurotransmitter in organisms as diverse as insects, worms, amphibians and mammals. It is the major excitatory neurotransmitter in the central nervous system (CNS) of mammals, and is therefore essential for all
of our behaviours. Although best known for its role at synapses in the mature nervous system, glutamate is also of vital importance during development where it regulates neurogenesis, neurite outgrowth, synaptogenesis and programmed cell death (apoptosis). Because of the well-established functions of neurotrophic factors in nervous system development, interactions between glutamate and neurotrophic factors have been sought, and found. Indeed, a delicate interplay between glutamate and neurotrophic factor signalling systems is at the heart of activity-dependent neuroplasticity during development and in the adult. (Mattson MP 2008)

Acute brain insults, such as traumatic brain injury, status epilepticus (prolonged epileptic crisis), or stroke are common etiologies for the development of epilepsy, including temporal lobe epilepsy (TLE), which is often refractory to drug therapy. The mechanisms by which a brain injury can lead to epilepsy are poorly understood. It is well recognized that excessive glutamatergic activity plays a major role in the initial pathological and pathophysiological damage. This initial damage is followed by a latent period, during which there is no seizure activity, yet a number of pathophysiological and structural alterations are taking place in key brain regions, that culminate in the expression of epilepsy. The process by which affected/injured neurons that have survived the acute insult, along with well-preserved neurons are progressively forming hyperexcitable, epileptic neuronal networks has been termed epileptogenesis. (Aroniadou-Anderjaska et al 2008)

Levels of several different neurotrophic factors are increased in response to epileptic seizures in animal models of epilepsy including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), basic fibroblast growth factor (bFGF), glial cell line-derived neurotrophic factor (GNTF), transforming growth factor-β (TGFβ) and TNFα. The most commonly used epileptic seizure model in which kainic acid is administered to rats or mice has been employed to demonstrate the involvement of endogenous growth factors in modifying neuronal vulnerability to seizures. By employing genetically modified mice, or by pharmacological inhibition of growth factors, it has been shown that BDNF, TGF-β and TNF play important roles in protecting neurons against seizure-induced damage and death. (Mattson MP 2008)

Brain-derived neurotrophic factor (BDNF) is particularly noteworthy for its apparent role as a mediator of the effects of environmental factors on hippocampal neurogenesis. Levels of BDNF are increased in the hippocampus in response to exercise, dietary energy restriction, and cognitive stimulation, all of which stimulate neurogenesis. (Mattson MP 2008)

An activity-dependent survival mechanism is believed to underlie the ability of exercise and intermittent fasting to prevent the death of neurons in experimental models of stroke. However, exercise and environmental enrichment did not protect hippocampal neurons against seizure-induced death despite a stimulation of BDNF production. (Mattson MP 2008)

Oxidative Stress and Epilepsy
Oxidative stress, a state of imbalance in the production of reactive oxygen species and nitrogen, is induced by a wide variety of factors. This biochemical state is associated with systemic diseases, and diseases affecting the central nervous system. Epilepsy is a chronic neurological disorder with refractoriness to drug therapy at about 30%. Currently, experimental evidence supports the involvement of oxidative stress in seizures, in the process of their generation, and in the mechanisms associated with refractoriness to drug therapy. (Cardenas-Rodriguez et al 2013)

A role for mitochondria and oxidative stress is emerging in acquired epilepsies such as temporal lobe epilepsy. TLE is characterized by chronic unprovoked seizures arising from an inciting insult with a variable seizure-free “latent period”. The mechanisms by which inciting injury induces chronic epilepsy, known as epileptogenesis involves multiple cellular, molecular and physiological changes resulting in altered hyperexcitable circuitry. Whether mitochondrial and redox mechanisms contribute to epileptogenesis remains to be fully clarified. Mitochondrial impairment is revealed in studies from human imaging and tissue analysis from TLE patients. The collective data from animal models suggest that steady-state mitochondrial reactive oxygen species and resultant oxidative damage to cellular macromolecules occurs during different phases of epileptogenesis. (Rowley & Patel 2013)

Inflammation is an early response to injury, although it remains controversial whether the inflammatory response is beneficial or detrimental to brain tissue. Chronic inflammation damages cells and is thought to be a key player in neurodegenerative disorders, such as Alzheimer’s Disease (AD). The point at which acute inflammation turns chronic is unclear. However, it has been suggested that sustained oxidative stress on cells of the CNS, associated with activation of NADPH oxidase (a membrane-bound enzyme complex) and production of reactive oxygen species, leads to amyloidogenic Aβ production and cell death in AD. (Weisman et al 2012)

Mitochondria are important integrators of cellular function and therefore affect the homeostatic balance of the cell. Besides their important role in producing adenosine triphosphate through oxidative phosphorylation, mitochondria are involved in the control of cytosolic calcium concentration, metabolism of key cellular intermediates, and Fe/S cluster biogenesis and contribute to programmed cell death. Mitochondria are also one of the major cellular producers of reactive oxygen species (ROS). Several human pathologies, including neurodegenerative diseases and cancer, are associated with mitochondrial dysfunction and increased ROS damage. (deMoura et al 2010)

The brain is uniquely vulnerable to oxidative stress-induced damage due to a large quantity of mitochondria, a high degree of oxidizable lipids and metals, high oxygen consumption, and less antioxidant capacity than other tissues making oxidative stress a likely contributor to neurological disorders such as the epilepsies. (Waldbaum & Patel 2010)

Oxidative stress and mitochondrial dysfunction are acute consequences of status epilepticus (SE). Recurrent seizures associated with the chronic phase of epilepsy coincided with the accumulation of mitochondrial DNA (mtDNA) damage, increased mitochondrial H2O2 levels, decreased expression of Ogg1 and Pol gamma and impaired mtDNA repair capacity. Together, increased oxidative mtDNA damage, mitochondrial H2O2 production and alterations in the mitochondrial base excision repair (mtBER) pathway provide evidence for mitochondrial oxidative stress in epilepsy and suggest that mitochondrial injury may contribute to epileptogenesis. (Jarrett et al 2008)

Epileptic seizures are a common feature of mitochondrial dysfunction associated with mitochondrial encephalopathies. Recent work suggests that chronic mitochondrial oxidative stress and resultant dysfunction can render the brain more susceptible to epileptic seizures. (Patel M 2004)

Neurotransmitters, Signaling Pathways and Genes in Epilepsy
Serotonin (5-hydroxytryptamine, 5-HT) is a classical neurotransmitter distributed in both the periphery and the central nervous system. Serotonin in the brain has extensive physiological functions including modulation of sleep, mood, emotion, learning and memory. Serotonergic signaling is altered in many neurological disorders such as Alzheimer’s disease, Parkinson’s disease, schizophrenia and depression. (Saobo Lei 2012)

The entorhinal cortex (EC) is considered as the gate to control the flow of information into and out of the hippocampus. The EC is important for numerous physiological functions such as emotional control, learning and memory and pathological disorders including Alzheimer’s disease, schizophrenia and temporal lobe epilepsy.Serotonin is a classical neurotransmitter which may modify these physiological functions and pathology of neurological diseases. The EC receives profuse serotonergic innervations from the raphe nuclei in the brainstem and expresses high density of serotonergic receptors including 5-HT1A, 5-HT1D, etc. Serotonin hyperpolarizes entorhinal neurons and inhibits the excitatory synaptic transmission via activation of 5-HT1A receptors but facilitates GABA release via activation of 5-HT2A receptors. (Saobo Lei 2012)

Serotonin – In recent years, there has been increasing evidence that serotonergic neurotransmission modulates a wide variety of experimentally induced seizures. Generally, agents that elevate extracellular serotonin (5-HT) levels, such as 5-hydroxytryptophan and serotonin reuptake blockers, inhibit both focal and generalized seizures, although exceptions have been described, too. Conversely, depletion of brain 5-HT lowers the threshold to audiogenically, chemically and electrically evoked convulsions. Furthermore, it has been shown that several anti-epileptic drugs increase endogenous extracellular 5-HT concentration. 5-HT receptors are expressed in almost all networks involved in epilepsies. Currently, the role of at least 5-HT(1A), 5-HT(2C), 5-HT(3) and 5-HT(7) receptor subtypes in epileptogenesis and/or propagation has been described. Mutant mice lacking 5-HT(1A) or 5-HT(2C) receptors show increased seizure activity and/or lower threshold. In general, hyperpolarization of glutamatergic neurons by 5-HT(1A) receptors and depolarization of GABAergic neurons by 5-HT(2C) receptors as well as antagonists of 5-HT(3) and 5-HT(7) receptors decrease the excitability in most, but not all, networks involved in epilepsies. Imaging data and analysis of resected tissue of epileptic patients, and studies in animal models all provide evidence that endogenous 5-HT, the activity of its receptors, and pharmaceuticals with serotonin agonist and/or antagonist properties play a significant role in the pathogenesis of epilepsies. (Bagdy et al 2007)

mTOR – The mTOR signaling pathway plays a major role in regulating gene transcription and protein translation and it has been deeply involved in several physiological and pathological conditions (Laplante and Sabatini, 2012). This pathway has also been recognized as a major signaling pathway in acquired epilepsies as well as a few mutation-based epilepsies (Cho, 2011). 

Rapamycin, an mTORC1 kinase inhibitor, blocks epileptogenesis and reduces the seizure frequency in the pilocarpine/kainate-injected rats when repeatedly administrated (Buckmaster et al., 2009; Zeng et al., 2009; Huang et al., 2010). 

Rapamycin also suppresses axonal sprouting of somatostatin-positive interneurons in the dentate/hilus (Buckmaster and Wen, 2011). A study shows that the sclerotic hippocampi of human specimen with refractory temporal lobe epilepsy, as well as kainate mouse model, have over-activated mTOR markers in reactive astrocytes (Sha et al., 2012; Sosunov et al., 2012). (Chang-Hoon Cho 2012)

Apolipoprotein E (ApoE) – The authors analyzed the association between APOE epsilon4 genotype and clinical and MRI findings in 43 refractory temporal lobe epilepsy patients. The distribution of the alleles were normal. Ten patients (23%) had an APOE epsilon 4 allele and had an earlier onset of habitual seizures (with epsilon4 5 +/- 5 years; without epsilon4 15 +/- 10 years). Quantitative MRI findings were not influenced by the APOE epsilon4 genotype. APOE epsilon4 may shorten the latency between an initial injury and seizure onset. (Briellmann et al 2000)

Interleukin 1 beta gene – The results show a modest association (OR, 1.48; 95% confidence interval, 1.09-2.00; P = 0.01) between the IL-1 beta-511T polymorphism and temporal lobe epilepsy with hippocampal sclerosis. (Kauffman et al 2008)

GABBR1 gene polymorphism(G1465A) – The present meta-analysis suggests that GABBR1 G1465A polymorphism is associated with the risk of TLE. The role of GABBR1 G1465A polymorphism in the development of TLE merits further investigation. (Xi et al 2011)

GABA, Neurosteroidogenesis and Epileptogenesis
Epileptogenesis is the process by which a brain becomes hyperexcitable and capable of generating recurrent spontaneous seizures. In humans, it has been hypothesized that following a brain insult there are a number of molecular and cellular changes that underlie the development of spontaneous seizures. Studies in animal models have shown that an injured brain may develop epileptiform activity before appearance of epileptic seizures and that the pathophysiology accompanying spontaneous seizures is associated with a dysfunction of γ-aminobutyric acid (GABA)ergic neurotransmission. Here, we analyzed the effects of status epilepticus on the expression of GABA(A) receptors (GABA(A) Rs) and scaffolding proteins involved in the regulation of GABA(A) R trafficking and anchoring. Analysis of tissue samples from the CA1 region of hippocampus show that status epilepticus promotes a loss of GABA(A) R subunits and of the scaffolding proteins associated with them. We also found a decrease in the levels of receptors located at the plasma membrane and alterations in GABA(A) R composition. (Gonzalez et al 2013)

Gaba-aminobutyric acid, the main inhibitory neurotransmitter in the brain, mediates its rapid inhibition through GABAA receptors. GABAA receptors have a pentameric structure with five subunits: 1) two of α1, α2, α3, or α5 subunits; 2) two β2 or β3 subunits (or one each); and 3) one γ2 subunit. These are arranged like the spokes of a wheel with a central chloride pore. Mutations of the GABAA receptor subunit genes (e.g., GABRA1, GABRB3, andGABRG2) are thought to alter receptor function and/or impair receptor biogenesis via multiple mechanisms, which may predispose affected patients to seizures. Some types of GABAA receptor subunit gene mutations have been associated with epilepsy, CAE, GEFS+, febrile seizures, juvenile myoclonic epilepsy, and Dravet syndrome. (Kim et al 2012)

We report the case of a woman who presented cryptogenic (of unknown causes temporal lobe seizures from the age of 43 years. Antiepileptic drug (AED) treatment with carbamazepine was able to control seizures for 1 year, but seizures relapsed and an add-on treatment with lamotrigine was started without achieving seizures control. The patient’s  medical history was unremarkable except for a mild hirsutism (excessive facial hair) for which she was taking finasteride since 45 years of age. In view of the possible relationship between finasteride, a known inhibitor of neurosteroids synthesis, and patient’s seizures exacerbation, we stopped finasteride resulting in prompt recovery of seizures control. It is known that 5α-dihydrosteroids are precursors of powerful positive modulators of γ-aminobutyric acid-A  inhibitory currents and exert antiseizure effects in animal epilepsy models. This case supports the hypothesis that endogenous neurosteroids can modulate seizure susceptibility and response to AEDs also in humans, suggesting their possible use as a new therapeutic option. (Pugnaghi et al 2013)

The principal prostatic androgen is dihydrotestosterone (DHT). Although not elevated in human benign prostatic hyperplasia, DHT levels in the prostate remain at a normal level with aging, despite a decrease in the plasma testosterone. DHT is generated by reduction of testosterone. Two isoenzymes of 5alpha-reductase have been discovered. Type 1 is present in most tissues of the body where 5alpha-reductase is expressed and is the dominant form in sebaceous glands. Type2 5alpha-reductase is the dominant isoenzyme in genital tissues, including the prostate. Finasteride is a 5alpha-reductase inhibitor that has been used for the treatment of benign prostatic hyperplasia and male-pattern baldness. At doses used clinically, its major effect is through suppression of type 2 5alpha-reductase, because it has a much lower affinity for the type 1 isoenzyme. Finasteride suppresses DHT by about 70% in serum and by as much as 85-90% in the prostate. The remaining DHT in the prostate is likely to be the result of type 1 5alpha-reductase. (Bartsch et al 2000)

Stress induces a physiological response which is mediated by the hypothalamic-pituitary-adrenal (HPA) axis. Corticotropin releasing hormone (CRH) release from the hypothalamus acts in the pituitary to signal the release of adrenocorticotropic hormone (ACTH), which triggers the release of cortisol from the adrenal gland in humans (corticosterone in mice). The HPA axis is regulated by numerous brain regions, neurotransmitter systems, and the negative feedback of steroid hormones (Herman et al., 2003;Larsen et al., 2003;Ulrich-Lai and Herman, 2009). These inputs impinge on CRH neurons in the paraventricular nucleus (PVN), mediating the output of the HPA axis. Although CRH neurons receive a wide variety of inputs from diverse brain regions, their activity is ultimately regulated by GABAergic inhibition (for review see (Herman et al., 2004;Decavel and van den Pol, 1990). (Sarkar et al 2011)

Blocking neurosteroidogenesis with finasteride is sufficient to block the stress-induced elevations in corticosterone that prevents stress-induced anxiety-like behaviors in mice. These data demonstrate that positive feedback of neurosteroids onto CRH neurons is required to mount the physiological response to stress. Further, GABAAR δ subunit-containing receptors and phosphorylation of KCC2 residue Ser940 may be novel targets for control of the stress response, which has therapeutic potential for numerous disorders associated with hyperexcitability of the HPA axis, including Cushing’s syndrome, epilepsy, and major depression. (Sarkar et al 2011)

Men with epilepsy often have sexual or reproductive abnormalities that are attributed to alterations in androgen levels, including subnormal free testosterone. Levels of the major metabolites of testosterone-androsterone (5alpha-androstan-3alpha-ol-17-one; 5alpha,3alpha-A), a neurosteroid that acts as a positive allosteric modulator of GABA(A) receptors, and its 5beta-epimer etiocholanolone (5beta-androstan-3alpha-ol-17-one; 5beta,3alpha-A)-also may be reduced in epilepsy. 5alpha,3alpha-A has been found in adult brain, and both metabolites, which also can be derived from androstenedione, are present in substantial quantities in serum along with their glucuronide and sulfate conjugates. 5alpha,3alpha-A and 5beta,3alpha-A have anticonvulsant properties. Although of low potency, the steroids are present in high abundance and could represent endogenous modulators of seizure susceptibility. (Kaminski et al 2005)

Besides its role in the androgen metabolism, 5α-reductase is thought to play an important role in the activation of neurosteroids via the 5α-reductase-3α-HSD complex. 5α-Reduced-3α-hydrogenated derivatives of progesterone and corticoids, but also androgens, are found to be potent mediators of the γ -aminobutyric acid receptor-regulated chloride channel. (Steckelbroeck et al 2001) 

Chronic Traumatic Encephalopathy
Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease that is a long-term consequence of single or repetitive closed head injuries for which there is no treatment and no definitive pre-mortem diagnosis. It has been closely tied to athletes who participate in contact sports like boxing, American football, soccer, professional wrestling and hockey. Risk factors include head trauma, presence of ApoE3 or ApoE4 allele, military service, and old age. It is histologically identified by the presence of tau-immunoreactive neurofibrillary tangles (NFTs) and neuropil threads (NTs) with some cases having a TDP-43 proteinopathy or beta-amyloid plaques. It has an insidious clinical presentation that begins with cognitive and emotional disturbances and can progress to Parkinsonian symptoms. The exact mechanism for CTE has not been precisely defined however, research suggests it is due to an ongoing metabolic and immunologic cascade called immunoexcitiotoxicity. (Saulle & Greenwald 2012)

Chronic traumatic encephalopathy has become a popular topic due to its close association with American football, hockey, soccer, boxing, and professional wrestling. Many of these affected athletes, mostly retired, have struggled in their later years with depression, substance abuse, anger, memory/motor disturbances, and suicide. Autopsy results from these athletes have suggested a link between these emotional, cognitive, and physical manifestations and CTE. (Saulle & Greenwald 2012)

At the time of injury mechanical perturbation of neurons is associated with a significant release of a host of neurotransmitters. Of particular importance is the release of glutamate and other excitatory amino acids with a resultant influx of extracellular Ca++ into the cell. This in turn releases additional Ca++ from intracellular stores, thus producing sufficient quantities of free intracellular Ca++ to initiate a host of intracellular reactions that can result in cytotoxic injury and eventually cell death. Second, mechanical perturbation of the neuron and its axon can result in mechanoporation (the creation of a traumatic defect) of the cell membrane and axolemma (the cell membrane surrounding an axon) with subsequent influx of extracellular Ca++ and other ions into the cell and axon. The mechanical distortion of the membrane does not resolve immediately and the ultimate fate of the membrane and the neuron appears related to the degree of distortion and other factors, with some cells repairing and resealing, and others progressing on to further disruption and cell death. (McAllister T 2011)

Given the partial overlapping of the clinical expression, epidemiology, and pathogenesis of chronic traumatic encephalopathy (CTE) and Alzheimer’s disease (AD), as well as the close association between traumatic brain injuries (TBIs) and neurofibrillary tangle formation, a mixed pathology promoted by pathogenetic cascades resulting in either CTE or AD has been postulated. (Costanza et al 2011)

As with other types of acute insult to the nervous system, traumatic brain injury (TBI) results in increased oxidative stress, impaired cellular energy metabolism and overactivation of glutamate receptors resulting in cellular Ca2+ overload. (Mattson MP 2008)

The Role of P2 Receptors and Microglial Cells in the Central Nervous System 
There is increasing interest in the involvement of purinergic signalling in the pathophysiology of the CNS, including trauma, ischaemia, epilepsy, neurodegenerative diseases, neuropsychiatric and mood disorders, and cancer, including gliomas. (Burnstock G 2013)

Purine and pyrimidine nucleotides are extracellular signaling molecules in the central nervous system (CNS) leaving the intracellular space of various CNS cell types via nonexocytotic mechanisms. In addition, ATP is a neuro-and gliotransmitter released by exocytosis from neurons and neuroglia. These nucleotides activate P2 receptors of the P2X (ligand-gated cationic channels) and P2Y (G protein-coupled receptors) types. (Koles et al 2011)

P2 receptors exist at neuroglia (e.g., astrocytes, oligodendrocytes) and microglia in the CNS. The neuroglial P2 receptors subserve the neuron-glia cross talk especially via their end-feets projecting to neighboring synapses. In addition, glial networks are able to communicate through coordinated oscillations of their intracellular Ca(2+) over considerable distances. P2 receptors are involved in the physiological regulation of CNS functions as well as in its pathophysiological dysregulation. Normal (motivation, reward, embryonic and postnatal development, neuroregeneration) and abnormal regulatory mechanisms (pain, neuroinflammation, neurodegeneration, epilepsy) are important examples for the significance of P2 receptor-mediated/modulated processes. (Koles et al 2011)

Purinergic signaling plays a unique role in the brain by integrating neuronal and glial cellular circuits. The metabotropic P1 adenosine receptors and P2Y nucleotide receptors and ionotropic P2X receptors control numerous physiological functions of neuronal and glial cells and have been implicated in a wide variety of neuropathologies. Emerging research suggests that purinergic receptor interactions between cells of the central nervous system (CNS) have relevance in the prevention and attenuation of neurodegenerative diseases resulting from chronic inflammation. CNS responses to chronic inflammation are largely dependent on interactions between different cell types (i.e., neurons and glia) and activation of signaling molecules including P2X and P2Y receptors. Whereas numerous P2 receptors contribute to functions of the CNS, the P2Y2 receptor is believed to play an important role in neuroprotection under inflammatory conditions. While acute inflammation is necessary for tissue repair due to injury, chronic inflammation contributes to neurodegeneration in Alzheimer’s disease and occurs when glial cells undergo prolonged activation resulting in extended release of proinflammatory cytokines and nucleotides. (Weisman et al 2012)

P2YR functions associated with the pathogenesis of inflammation in the CNS, a process involving astrocyte and microglial cell proliferation and migration to a site of injury (i.e., gliosis), can be induced by a variety of conditions (e.g., oxidative stress or excessive β-amyloid (Aβ) peptide production) that stimulate the release of proinflammatory mediators, including cytokines. Among these mediators, ATP and other nucleotides also can be released into the extracellular space due to cell damage, oxidative stress, hypoxia, ischemia, or mechanical stress, whereupon the nucleotides activate P2X and P2Y receptors expressed in surrounding cells. Several studies have proposed the involvement of P2Rs, including the P2X7R and P2Y2R, in proinflammatory responses mediated by glial cells that are associated with neurodegenerative diseases. In the absence of inflammation, P2Y2R expression levels are low in neurons, but the presence of IL-1β upregulates P2Y2R expression. As mentioned above, we will focus on the role of P2Y2Rs in the regulation of neuroprotective responses associated with inflammation. (Weisman et al 2012)

Accumulating experimental evidence indicates that brain immune response and inflammatory mediators decrease the threshold for individual seizures and contributes to the process of epileptogenesis. (Gnatek et al 2012)

Inflammatory injury, microglial activation and cell proliferation are closely related after seizures, microglial activation may be an important mechanism in the inflammatory injury of epilepsy. (Sun et al 2012) Microglial cell activation by the proinflammatory cytokines TNF-α, IL-1β, and IL-6 is accompanied by partial rounding and increased cell motility and proliferation. The finding that P2Y2R expression under proinflammatory conditions is regulated by NF-κB binding to the P2Y2R promoter is consistent with the established role of NF-κB activation in the induction of inflammation. (Weisman et al 2012)

Dysregulation of the neurosupportive role of glia can potentially contribute to neurologic disease progression, through an increased production of proinflammatory cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and S100B. A recognized response to seizures and a potential contributor to mechanisms of epileptogenesis is excessive or prolonged glial activation and the associated increase in proinflammatory cytokine production including IL-1β and TNF-α. Indeed, inflammation in the immature brain leads to long-term increase in seizure susceptibility. (Somera-Molina et al 2009)

Various CNS insults lead to production of TNFα, including seizures, and both neurons and glia can produce and react to TNFα. TNFR1 (TNF receptor 1) signaling may contribute to the pathophysiology of seizure-induced neuronal death. Binding of TNFR1 to TRADD and TRADD to RIP is increased following status epilepticus in rats and seizure-induced neuronal death can be reduced by TNFα–neutralizing antibodies. There is evidence supporting activation of caspase-8, as well as ASK1, by seizures, and active caspase trapping experiments show that caspase-8 activation is also an apical event following seizure-like insults in vitro. Caspase-8 pseudosubstrate inhibitors are also reported to reduce seizure-induced neuronal death in vitro and in vivo. Last, TNFR1-TRADD (TNFR-associated death domain) and TRADD-FADD (Fas associated death domain) complexes are present in biopsy samples from resected hippocampi from patients with temporal lobe epilepsy. (Thompson et al 2011)

The major findings in the present study are that TNF-α signaling showed cellular specific responses of NF-κBphosphorylation in the PC following status epilepticus, which may be related to vasogenic edema formation followed by neutrophil infiltration. (Kim et al 2012)

Blood Tests in Epilepsy
Apolipoprotein E (ApoE) – We found that ApoE epsilon4 carriers in our population had a non-significant earlier age of epilepsy onset than non-carriers. The meta-analysis confirmed this finding, showing that ApoE epsilon4 carriers had epilepsy onset almost 4 years earlier than non-carriers (mean difference 5.15 years; CI 95% 2.08-6.22; p=0.001). In conclusion, the ApoE epsilon4 isoform is a genetic factor that might influence the age at onset of temporal lobe epilepsy. (Kauffman et al 2010)

Free Testosterone – Men with epilepsy often have sexual or reproductive abnormalities that are attributed to alterations in androgen levels, including subnormal free testosterone. (Kaminski et al 2005)

Sodium – According to the previous reports, the rate of hyponatremia (decreased serum sodium) in patients receiving Carbamazepine (CBZ) is not small. It ranges from 48% to 31%. As CBZ is frequently used for patients with epilepsy and neuralgia, not only their blood CBZ concentration but also their serum Na level should be monitored. (Inamura et al 1999)

Uric Acid, Serum  – Usually hypouricemia is due to drugs and toxic agents, sometimes it is due to diet or genetics, and rarely it is due to an underlying medical condition. Hypouricemia is common in vegetarians due to the lowpurine content of most vegetarian diets. Vegetarian diet has been found to result in mean serum uric acid values as low as 239 µmol/L (2.7 mg/dL). (wikipedia.org)

Vitamin D – Prophylaxis with vitamin D is recommended for all subjects using antiepileptic drugs (AEDs). Due to increased catabolism of vitamin D, higher than normally recommended doses (up to 7,000 IU per day) of vitamin D are required for optimal effect, particularly for those with low vitamin D levels, high risk of bone disease and/or with documented low bone mineral density (BMD). In general, in patients undergoing antiepileptic treatment, vitamin D status should be monitored once to twice annually, based on the serum 25(OH)D level (target: 30–60 ng/mL [75–150 nmol/L]). Any deficiency should be treated as required with targeted supplementation in order to prevent osteopathy. For those with documented vitamin D deficiency, treatment with 50,000 IU vitamin D/week for 8 weeks is recommended, followed by 50,000 IU of vitamin D every 2 to 4 weeks thereafter. (Grober & Kisters 2012)

Studies on Natural Compounds in Epilepsy
Alpha-tocopherol – Our findings strongly support the hypothesis that oxidative stress occurs in hippocampus during pilocarpine-induced seizures, indicate that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and imply that strong protective effect could be achieved using alpha-tocopherol. (Tome et al 2010) Alpha-tocopherol is the form of vitamin E that is preferentially absorbed and accumulated in humans. It is the main source found in supplements and in the European diet, where the main dietary sources are olive and sunflower oils.

Antioxidants – Oxidative stress and mitochondrial dysfunction are involved in neuronal death and seizures. There is evidence that suggests that antioxidant therapy may reduce lesions induced by oxidative free radicals in some animal seizure models. Studies have demonstrated that mitochondrial dysfunction is associated with chronic oxidative stress and may have an essential role in the epileptogenesis process; however, few studies have shown an established link between oxidative stress, seizures, and age. (Aguiar et al 2012)

Antioxidants – Oxidative stress resulting from excessive free-radical release is likely implicated in the initiation and progression of epilepsy. Therefore, antioxidant therapies aimed at reducing oxidative stress have received considerable attention in epilepsy treatment. This review highlights pharmacological mechanisms associated with oxidative stress in epileptic seizures and the potential for neuroprotection in epilepsy that targets oxidative stress and is supported by effective antioxidant treatment. (Shin et al 2011)

Ashwagandha (a main ingredient of Ashwagandharishta) and flax seed oil  – The present study reveals that both Ashwagandharishta and flax seed oil are having antiepileptic activity; besides, they are having excellent anti–post-ictal depression effect. The observed activity may be mediated through inhibition of voltage-dependant Na+ channels or by blocking glutaminergic excitation mediated by the N–methyl–d–aspartate (NMDA) receptor. However, further detailed investigations are needed to explore the exact mechanism involved. Further, both the drugs can play a major role as an adjuvant therapy with modern antiepileptic drugs; however, this needs detailed investigations. (Tanna et al 2012) 

Baicalin – Pretreatment with baicalin (a flavonoid compound purified from plant Scutellaria baicalensis) significantly delayed the onset of the first limbic seizures and SE (status epilepticus), reduced the mortality rate, and attenuated the changes in the levels of lipid peroxidation, nitrite content and reduced glutathione in the hippocampus of pilocarpine-treated rats. Furthermore, we also found that baicalin attenuated the neuronal cell loss, apoptosis, and degeneration caused by pilocarpine-induced seizures in rat hippocampus. Collectively, these results indicated remarkable anticonvulsant and neuroprotective effects of baicalin and should encourage further studies to investigate baicalin as an adjuvant in epilepsy both to prevent seizures and to protect against seizure induced brain injury. (Liu et al 2012) 

Coenzyme Q10 (CoQ10) – Conventional antiepileptic drugs fail to adequately control seizures and predispose to cognitive impairment and oxidative stress with chronic usage in a significant proportion of patients with epilepsy. Coenzyme Q10 (CoQ10), an antioxidant compound, exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. Our findings strongly suggest that CoQ10 can be considered a safe and effective adjuvant to phenytoin therapy in epilepsy both to ameliorate seizure severity and to protect against seizure-induced oxidative damage by reducing the cognitive impairment and oxidative stress associated with chronic use of phenytoin. (Tawfik MK 2011)

Curcumin – an active ingredient of turmeric with antioxidant and anti-inflammatory properties has recently been reported to have anticonvulsant effects in several animal models of epilepsy. Curcumin has anticonvulsant activity in the pilocarpine rat model of seizures, and that modulation of free radicals and nitric oxide synthase may be involved in this effect. (Du et al 2012) 

Curcumin and Nigella sativa oil – This animal study reflects the promising anticonvulsant and potent antioxidant effects of curcumin and Nigella sativa oil in reducing oxidative stress, excitability and the induction of seizures in epileptic animals and improving some of the adverse effects of antiepileptic drugs. (Ezz et al 2011) 

Docosahexaenoic acid (DHA) – The entorhinal cortex (EC) and hippocampus are among the brain regions where neurofibrillary tangles and amyloid-beta (Aβ) plaques first develop in Alzheimer’s Disease (AD) patients.  Defects in neuronal activity of the entorhinal cortex (EC) are suspected to underlie the symptoms of Alzheimer’s disease. Our results indicate that cognitive performance and basic physiology of EC neurons depend on DHA intake in a mouse model of AD. (Arsenault et al 2011) 

Gotu kola (Centella asiatica) – The extracts of C. asiatica, except acqueous extract, possess anticonvulsant and neuroprotective activity in this animal study and thus can be used for effective management in treatment of epileptic seizures. (Visweswari et al 2010)

Honokiol and Magnolol – In this animal study the anti-convulsant effects of these two compounds on NMDA-induced seizures were also evaluated. After honokiol or magnolol (1 and 5 mg/kg, i.p.) pretreatment, the seizure thresholds of NMRI mice were determined by tail-vein infusion of NMDA (10 mg/ml). Data showed that both honokiol and magnolol significantly increased the NMDA-induced seizure thresholds, and honokiol was more potent than magnolol. These results demonstrated that magnolol and honokiol have differential effects on NMDA and non-NMDA receptors, suggesting that the distinct therapeutic applications of these two compounds for neuroprotection should be considered. (Lin et al 2005)

Lipoic acid (also known as alpha-lipoic acid) – Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, proving that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and also imply that strong protective effect could be achieved using lipoic acid as an antioxidant. (Freitas RM 2009)

Omega-3 polyunsaturated fatty acids (n-3 PUFAs  – We examined whether a dietary supplement containing omega-3 polyunsaturated fatty acids (n-3 PUFAs) can alleviate and/or reduce the frequency of epileptic seizures in patients with central nervous system (CNS) diseases treated with anticonvulsive drugs (ACDs). A special spread containing 65% n-3 PUFAs was added to the daily diet. The patients consumed 5 g of this spread at every breakfast for 6 months. Five patients completed the study. In all of them, a marked reduction in both frequency and strength of the epileptic seizures was recorded. Incorporation of the dietary supplement containing n-3 PUFAs may be beneficial in suppression of some cases of epileptic seizures. (Schlangere et al 2002)

Resveratrol has neuroprotective features both in vitro and in vivo in models of Alzheimer’s disease (AD), but it has proved to be beneficial also in ischemic stroke, Parkinson’s disease, Huntington’s disease, and epilepsy. Here, we summarize the in vitro and in vivo experimental results highlighting the possible role of resveratrol as neuroprotective biofactor with a particular focus on AD. (Albani et al 2010)

Taurine – The data from this and previous studies provide strong evidence for the neuroprotective role of taurine in the GABAergic system. In this animal study the authors describe the efficacy of taurine in decreasing picrotoxin-induced seizures. (L’Amoreaux et al 2010)

Ubiquinone – Recent researches have shown that antioxidant compounds may have certain neuroprotective effect against the neurotoxicity of seizures at cellular level. Ubiquinone, an antioxidant compound, exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, which indicates that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences. Our result also suggests that ubiquinone can exert significant neuroprotective effects that might be useful in the treatment of neurodegenerative diseases. (Santos et al 2010)

Walnut Kernels (WK) – have high concentrations of phenolic compounds, which have beneficial effects on human health because of their antioxidant and anti-atherogenic properties. The present study was designed to evaluate the efficacy of WK supplementation for the prevention of experimental epilepsy in male rats. WKs displayed anti-epileptogenic properties, and WK supplementation was associated with increased seizure threshold and reduced mortality in the experimental group versus controls. (Shekaari et al 2012)

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