Hormonal and reproductive disturbances in epileptic male patients: Emerging issues

Effects of autonomic nervous system disorders on male infertility

The male reproductive functions are largely regulated by the autonomic nervous system. Male sexual behavior and fertility primarily depend on the normal function of the higher neural centers related to the autonomic nervous system, the hypothalamic-pituitary-gonadal axis, the autonomic nervous components within the spinal cord and spinal nerves, and certain somatic nerves in the pelvic floor. In this review article, we will summarize the role of the autonomic nervous system in regulating male reproductive capabilities and fertility, its impact on male infertility under abnormal conditions, including the role of drug-induced autonomic nervous dysfunctions on male infertility. The main purpose of this article was to provide an overview of the effects of autonomic nervous dysfunction on male reproductive function and shed light on the potential therapeutic target for male infertility.

Quercetin Protects against Levetiracetam induced gonadotoxicity in rats

The purpose of this study was to determine whether quercetin may counteract the negative effects of levetiracetam on rat reproductive capabilities by examining its influence on a few reproductive parameters following levetiracetam administration. Twenty (20) experimental rats were employed, with five (n = 5) animals per treatment group. Rats in group 1 received saline (10mL/kg, p.o.) which served as control. Quercetin (20mg/kg, p.o./day) was given to groups 2 and 4 for 28 days starting from 29 to 56 days, respectively. However, animals in groups 3-4 received LEV (300mg/kg) once daily for 56 days with a 30-minute break in between treatments. All rats had their serum sex hormone levels, sperm characteristics, testicular antioxidant capability, and levels of oxido-inflammatory/apoptotic mediators evaluated. Additionally, the expression of proteins associated to BTB, autophagy, stress response was examined in rat testes. LEV increased sperm morphological defects and decreased sperm motility, sperm viability, sperm count body weight and testes weight, MDA and 8OHdG levels in the testis of LEV-treated rats were elevated, while antioxidant enzyme expression was concurrently decreased. Additionally, it reduced the levels of serum gonadotropins, testosterone, mitochondrial membrane potential, and cytochrome C liberation into the cytosol from the mitochondria. Caspase-3 and Caspase-9 activity increased. While Bcl-2, Cx-43, Nrf2, HO-1, mTOR, and Atg-7 levels were lowered, NOX-1, TNF-α, NF-kß, IL-1ß, and tDFI levels increased. Histopathological scoring provided further support for the decreased spermatogenesis. In contrast to all of these gonadotoxic effects of LEV, improvements in LEV-induced gonadal damage were seen through upregulation of Nrf2/ HO-1, Cx-43/NOX-1, mTOR/Atg-7 expression and attenuation of hypogonadism, poor sperm quality, mitochondria-mediated apoptosis, and oxidative inflammation due to quercetin post-treatment. The modulation of Nrf2/HO-1, /mTOR/Atg-7 and Cx-43/NOX-1 levels and the inhibition of mitochondria-mediated apoptosis and oxido-inflammation in LEV-induced gonadotoxicity in rats suggest that quercetin may hold promise as a possible therapeutic treatment.

Carbamazepine adversely altered the pituitary-testicular axis with resultant reproductive dysfunctions than levetiracetam or carbamazepine-levetiracetam adjuvant treatment in male Wistar rat

This study investigated the on-toward reactions of individual or adjunctive treatment with carbamazepine (CBZ) and levetiracetam (LEV) on the pituitary-testicular axis in male rats. Twenty-four male Wistar rats were randomised into 4 groups (n = 6) and received daily intraperitoneal (i.p) treatment of normal saline (0.1 ml/day); CBZ (25 mg/kg i.p); LEV (50 mg/kg i.p); or combination of CBZ (12.5 mg/kg) and LEV (25 mg/kg) for 4 weeks. The serum concentration of luteinising hormone (LH), follicle-stimulating hormone (FSH), and testosterone was determined. Also, the seminal profile and histomorphological status of the testis were determined. Data were analysed using descriptive and inferential statistics. The control and test groups were compared using Student's t test, analysis of variance (ANOVA), and Student-Newman-Keuls post hoc analysis where appropriate, while the results presented as mean ± SEM in graphs or tables. The level of significance was taken at p < .05. The percentage motility, viability, and concentration of FSH decreased significantly in all the treatment groups, while the testis was presented with various forms of histomorphological aberrations. This study concludes that CBZ, and CBZ + LEV adjunctive treatments alter the pituitary-testicular axis with evidence of hormonal deregulation and alteration in the reproductive functions' indices, while LEV treatment remains the safest.

Valproic Acid and Epilepsy: From Molecular Mechanisms to Clinical Evidences

After more than a century from its discovery, valproic acid (VPA) still represents one of the most efficient antiepi-leptic drugs (AEDs). Pre and post-synaptic effects of VPA depend on a very broad spectrum of actions, including the regu-lation of ionic currents and the facilitation of GABAergic over glutamatergic transmission. As a result, VPA indirectly mod-ulates neurotransmitter release and strengthens the threshold for seizure activity. However, even though participating to the anticonvulsant action, such mechanisms seem to have minor impact on epileptogenesis. Nonetheless, VPA has been reported to exert anti-epileptogenic effects. Epigenetic mechanisms, including histone deacetylases (HDACs), BDNF and GDNF modulation are pivotal to orientate neurons toward a neuroprotective status and promote dendritic spines organization. From such broad spectrum of actions comes constantly enlarging indications for VPA. It represents a drug of choice in child and adult with epilepsy, with either general or focal seizures, and is a consistent and safe IV option in generalized convulsive sta-tus epilepticus. Moreover, since VPA modulates DNA transcription through HDACs, recent evidences point to its use as an anti-nociceptive in migraine prophylaxis, and, even more interestingly, as a positive modulator of chemotherapy in cancer treatment. Furthermore, VPA-induced neuroprotection is under investigation for benefit in stroke and traumatic brain injury. Hence, VPA has still got its place in epilepsy, and yet deserves attention for its use far beyond neurological diseases. In this review, we aim to highlight, with a translational intent, the molecular basis and the clinical indications of VPA.

The role of polytherapy in the management of epilepsy: suggestions for rational antiepileptic drug selection

Introduction: Antiepileptic polytherapy may be indicated in patients experiencing drug-resistant epilepsy. To date, there are no evidence-based criteria on how to combine different antiepileptic drugs (AEDs) together, in order to obtain the best therapeutic response.Areas covered: This paper reviews the available data about the various associations of AEDs in patients undergoing polytherapy, focusing on the most effective and well-tolerated polytherapies. Moreover, some controversial aspects of this topic are addressed.Expert opinion: Nowadays, there are no guidelines on polytherapy in patients with epilepsy; thus, the management of pharmacoresistant epilepsy is still uncertain, except for valproate/lamotrigine combination, which seems to be the only one recommended. Data regarding mechanism of action, pharmacokinetics, tolerability, and, more importantly, the analysis of the valuable clinical studies of drug combinations can help physicians to choose the best and most effective AED association for each patient.

Pharmacological modulation of cell functional activity with valproic acid and erythropoietin

Introduction: Valproic acid (VA) is carboxylic acid with a branched chain, which is used as an antiepileptic drug.

Valproic acid influence on cells in vivo: VA, which is an antiepileptic drug, is also a teratogen, which causes defects of a neural tube and an axial skeleton, although the mechanisms are not yet fully clear.

Valproic acid influence on mesenchymal stem cells (MSC) in vitro: It is shown that valproic acid reduces the intracellular level of oxygen active forms.

Valproic acid effect on tumor cells: VA inhibits tumor growth through several mechanisms, including the cell cycle stop, differentiation induction and inhibition of growth of tumor vessels.

Valproic acid influence on enzymes: It affects mainly GSK-3.

Valproic acid influence on animals’ cells: It is shown that VA can significantly improve an ability to develop in vitro and improve nuclear reprogramming of embryos.

Erythropoietin (EPO): Is an hypoxia-induced hormone and a cytokine, which is necessary for normal erythropoiesis. EPO is widely used in in vitro experiments.

Conclusion: Thus, the influence of VA and EPO on cells can be used in cell technologies.

Endocrine complications of celiac disease: a case report and review of the literature

PURPOSE

The purpose of this article is to review recent literature regarding endocrine disorders related to celiac disease (CD).

METHODS

We describe a case report and review existing literature on the endocrine manifestations of CD.

RESULTS

CD is an autoimmune disorder characterized by intestinal inflammation in response to gluten. CD can cause a wide range of extra-intestinal complications, including endocrine manifestations. Metabolic bone disease including osteoporosis and osteopenia, vitamin D deficiency, secondary hyperparathyroidism and less frequently osteomalacia can be seen. In CD, fracture risk is increased by 30-40%, while risk for hip fracture is approximately doubled. The risk for other endocrine disorders, particularly autoimmune endocrinopathies, is also increased in those with CD compared to the general population. Epidemiologic data indicate the risk for hypothyroidism is 3-4 times higher among those with CD, while risk of type 1 diabetes is greater than double. Risk for primary adrenal insufficiency is a striking 11-fold higher in those with versus without CD, though the absolute risk is low. Fertility is reduced in women with CD before diagnosis by 37% while male fertility in the absence of hypogonadism does not appear to be affected. Other endocrine conditions including hyperthyroidism, ovarian failure, androgen insensitivity, impaired growth and growth hormone deficiency and autoimmune polyendocrine syndromes have also been associated with CD.

CONCLUSIONS

CD is associated with a wide range of endocrine manifestations.

The Association Between Psychotropic Drug Use and Fertility Problems Among Male Subjects

Mental disorders affect a high percentage of the general population and are associated with a significant burden. One major component of treatment for mental illnesses is pharmacotherapy. Various psychotropic medications are used in the treatment of psychiatric disorders and these are often associated with a plethora of side effects. The many side effects of psychotropic drugs can severely impair patients' quality of life and decrease their adherence to treatment. Among the relatively neglected and less-studied potential side effects of psychotropic drugs are impairment of sperm parameters and fertility problems among male patients. This article summarizes the data with regard to the effects of 6 widely used psychotropic drugs-lithium, valproate, haloperidol, olanzapine, imipramine, and fluoxetine-on sexual function and sperm parameters in male subjects. In general, the reviewed data suggest that these medications can be associated with sexual function problems and negative effects on sperm parameters among male subjects. It is important to note that most of the data are based on preclinical studies and nonrandomized clinical trials with relatively small sample sizes, so that it is not possible to draw unequivocal conclusions with regard to the clinical relevance of the findings. Prospective, randomized clinical trials are necessary to elucidate the effects of psychotropic drugs on men's sperm parameters and fertility indices per se.

Effects of valproate on reproductive endocrine function in male patients with epilepsy: A systematic review and meta-analysis

BACKGROUND

Valproate (VPA) is a broad spectrum antiepileptic drug (AED) that is generally used as a first line agent for most idiopathic and symptomatic generalized epilepsies. Many studies have indicated that AEDs cause reproductive endocrine disorders in males, but the exact etiology underpinning these dysfunctions is not clear. This meta-analysis and systematic review was intended to evaluate the effect of VPA on reproductive endocrine function in male patients with epilepsy.

METHODS

A literature search was performed using electronic databases up to December 2017 for eligible studies. The differences in the levels of the reproductive factors, luteinizing hormone (LH), follicle-stimulating hormone (FSH), sex hormone binding globulin (SHBG), testosterone, dehydroepiandrosterone sulfate (DHEAS), and androstenedione (ADION) in the male patients with epilepsy treated with VPA (treatment group) were compared with the those of the healthy controls (control group) by the use of the Standardized mean difference (SMD) with 95% confidence intervals (CIs).

RESULTS

Six publications with a total of 316 subjects were identified. The result revealed that the levels of FSH (SMD = -1.33, 95% CI: -2.60 to -0.07, P = 0.039) and testosterone (SMD = -0.45, 95% CI: -0.87 to -0.03, P = 0.038) of the treatment group were decreased significantly compared with the healthy controls. There was an increase in the levels of SHBG (SMD = 0.41, 95% CI: -0.21 to 1.03, P = 0.197), DHEAS (SMD = 0.20, 95% CI: -0.06 to 0.45, P = 0.126) and ADION (SMD = 0.73, 95% CI: -0.10 to 1.57, P = 0.086), and a decrease in that of LH(SMD = -0.71, 95% CI: -1.49 to 0.07, P = 0.075) in the male patients with epilepsy treated with VPA, but the differences did not reach statistical significance (P > 0.05).

CONCLUSIONS

This meta-analysis indicates that VPA may lead to a significant decrease in the levels of FSH and testosterone and alter the concentrations of LH, DHEAS, SHBG, and ADION to some extent, which might contribute to the reproductive endocrine dysfunction in male patients with epilepsy. It is important for clinical neurologists to be cautious when prescribing VPA to reproductive-aged male patients with epilepsy.

Reproductive toxicity after levetiracetam administration in male rats: Evidence for role of hormonal status and oxidative stress

Levetiracetam (LEV) is an antiepileptic drug commonly used in the treatment of epilepsy because of its excellent safety profile in all age groups. It is remarkable that there are no studies evaluating the toxic effects of this drug on the male reproductive system, as it is commonly used in male patients of reproductive age. From this point of view, our aim was to evaluate the possible toxic effects of LEV on the male reproductive system. Therefore, LEV was administered to male rats orally at 50, 150, and 300 mg/kg for 70 consecutive days. At the end of this period, alterations to body and organ weights were calculated, and sperm concentration, motility, and morphology were investigated by a computer-assisted sperm analysis system. Sperm DNA damage was determined by comet assay and histopathological examination of the testes was carried out. Serum testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were measured by ELISAs to determine the effects of hormonal status, while glutathione, superoxide dismutase, catalase, and malondialdehyde levels in the testes were measured by colorimetric assay kits to determine the role of oxidative status in potential toxicity. According to the results, sperm quality was decreased by LEV treatment in a dose-dependent manner. LEV induced significant DNA damage in the 150 and 300 mg/kg LEV-administered groups. Histopathology of the testes showed that LEV resulted in testicular injury in the 300 mg/kg LEV-administered group. Serum testosterone, FSH, and LH levels were significantly decreased in the 300 mg/kg LEV-administered group. Glutathione, superoxide dismutase, and catalase levels were significantly decreased in all experimental groups while malondialdehyde levels were significantly increased in 150 and 300 mg/kg LEV-administered groups. According to these results, it was determined that LEV administration decreased sperm quality and it was alleged that hormonal alteration and oxidative stress are potential contributors to reproductive toxicity.

Psychotropics and Male Reproduction

Psychotropic drugs, including antidepressants, antipsychotics, and anticonvulsants, all have negative effects on sexual function and semen quality. These adverse events vary among men and are less pronounced for some medications, allowing their effects to be managed to some extent. Use of specific serotonin reuptake inhibitors (SSRIs) is prevalent in men of reproductive age; and application to treat premature ejaculation increases the number of young men on SSRI therapy. Oxidative damage to sperm can result from prolonged residence in the male reproductive tract. The increase in ejaculatory latency seen with SSRIs likely underlies some of their negative effects on semen quality, including higher sperm DNA fragmentation, seen in all SSRIs evaluated thus far. These medications increase prolactin (PRL) levels in some men, and this is often credited with inhibitory effects on male reproduction; however, testosterone levels are generally normal, reducing the likelihood of direct HPG axis inhibition by PRL. The tricyclic antidepressants have also been shown to increase PRL levels in some studies but not in others. The exception is the tricyclic antidepressant clomipramine, which profoundly increases PRL levels and may depress semen quality. Other antidepressants modulating synaptic levels of serotonin, norepinephrine, and/or dopamine may have toxicity similar to SSRIs, but most have not been evaluated. In limited studies, norepinephrine-dopamine reuptake inhibitors (NDRIs) and serotonin agonist/reuptake inhibitors (SARIs) have had minimal effects on PRL levels and on sexual side effects. Antipsychotic medications increase PRL, decrease testosterone, and increase sexual side effects, including ejaculatory dysfunction. The greatest evidence is for chlorpromazine, haloperidol, reserpine, risperidone, and thioridazine, with less effects seen with aripiprazole and clozapine. Remarkably few studies have looked at antipsychotic effects on semen quality, and this is an important knowledge gap in reproductive pharmacology. Lithium increases PRL and LH levels and decreases testosterone although this is informed by few studies. The anticonvulsants, many used for other indications, generally decrease free or bioavailable testosterone with variable effects on the other reproductive hormones. Valproate, carbamazepine, oxcarbazepine, and levetiracetam decrease semen quality; other anticonvulsants have not been investigated for this adverse reaction. Studies are required evaluating endpoints of pregnancy and offspring health for psychotropic medications.

Limited Effect of Chronic Valproic Acid Treatment in a Mouse Model of Machado-Joseph Disease

Machado-Joseph disease (MJD) is an inherited neurodegenerative disease, caused by a CAG repeat expansion within the coding region of ATXN3 gene, and which currently lacks effective treatment. In this work we tested the therapeutic efficacy of chronic treatment with valproic acid (VPA) (200mg/kg), a compound with known neuroprotection activity, and previously shown to be effective in cell, fly and nematode models of MJD. We show that chronic VPA treatment in the CMVMJD135 mouse model had limited effects in the motor deficits of these mice, seen mostly at late stages in the motor swimming, beam walk, rotarod and spontaneous locomotor activity tests, and did not modify the ATXN3 inclusion load and astrogliosis in affected brain regions. However, VPA chronic treatment was able to increase GRP78 protein levels at 30 weeks of age, one of its known neuroprotective effects, confirming target engagement. In spite of limited results, the use of another dosage of VPA or of VPA in a combined therapy with molecules targeting other pathways, cannot be excluded as potential strategies for MJD therapeutics.

The biomarker sex hormone-binding globulin - from established applications to emerging trends in clinical medicine

Sex hormone-binding globulin (SHBG) is a serum glycoprotein exhibiting the unique feature of binding sex steroids with high affinity and specificity. Its serum levels are regulated not only by androgens and estrogens but also by thyroid hormones and other metabolic factors. Several disease conditions are accompanied by altered SHBG levels such as hyper- and hypoandrogenism, thyroid disorders, pituitary diseases, liver disorders, and breast as well as prostate cancer. Additionally, several drugs and alcohol consumption influence serum concentrations of SHBG. In some cases, altered SHBG levels are a specific result of the underlying pathology. In others, they merely constitute an epiphenomenon, which still might offer the possibility of using serum measurements of SHBG as surrogate marker. This review article portrays the different disorders associated with altered SHBG levels and discusses the usefulness of SHBG as disease biomarker from a clinicians as well as from an endocrinological researchers point of view.

Effects of aqueous extract of Ruta graveolens and its ingredients on cytochrome P450, uridine diphosphate (UDP)-glucuronosyltransferase, and reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H)-quinone oxidoreductase in mice

Ruta graveolens (the common rue) has been used for various therapeutic purposes, including relief of rheumatism and treatment of circulatory disorder. To elucidate the effects of rue on main drug-metabolizing enzymes, effects of an aqueous extract of the aerial part of rue and its ingredients on cytochrome P450 (P450/CYP), uridine diphosphate (UDP)-glucuronosyltransferase, and reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H):quinone oxidoreductase were studied in C57BL/6JNarl mice. Oral administration of rue extract to males increased hepatic Cyp1a and Cyp2b activities in a dose-dependent manner. Under a 7-day treatment regimen, rue extract (0.5 g/kg) induced hepatic Cyp1a and Cyp2b activities and protein levels in males and females. This treatment increased hepatic UDP-glucuronosyltransferase activity only in males. However, NAD(P)H:quinone oxidoreductase activity remained unchanged. Based on the contents of rutin and furanocoumarins of mouse dose of rue extract, rutin increased hepatic Cyp1a activity and the mixture of furanocoumarins (F_mix) increased Cyp2b activities in males. The mixture of rutin and F_mix increased Cyp1a and Cyp2b activities. These results revealed that rutin and F_mix contributed at least in part to the P450 induction by rue.

Management of male neurologic patients with infertility

Many aspects of fertility rely on intact neurologic function and thus neurologic diseases can result in infertility. While research into general female fertility and alterations in male semen quality is limited, we have an abundance of knowledge regarding ejaculatory dysfunction following nerve injury. Normal ejaculation is the result of coordinated reflex activity involving both the sympathetic and somatic nervous systems. Nerve injury can result in retrograde ejaculation, and anejaculation. With retrograde ejaculation, the ejaculate is propelled into the bladder instead of out through the urethra. In mild cases this condition can be reversed by sympathomimetic medications and, in more severe cases, sperm cells can be extracted from the bladder following ejaculation. With anejaculation, the ejaculatory reflex is not activated by normal sexual stimulation. In such cases, the first choice of treatment is assisted ejaculation, preferably by penile vibratory stimulation. If vibratory stimulation is unsuccessful, then ejaculation can almost always be induced by electroejaculation. In cases where assisted ejaculation fails, sperm can be retrieved surgically from either the epididymis or from the testis. Once viable sperm cells have been obtained, these are used in assisted reproductive techniques, including intravaginal insemination, intrauterine insemination, and in vitro fertilization/intracytoplasmic sperm injection.

Effect of sildenafil, a selective phosphodiesterase 5 inhibitor, on the anticonvulsant action of some antiepileptic drugs in the mouse 6-Hz psychomotor seizure model

Sildenafil, a selective phosphodiesterase 5 inhibitor (PDE5), has been recently reported to have both pro- and anticonvulsant action in various experimental models of seizures and epilepsy. Furthermore, it affects anticonvulsant action of some antiepileptic drugs (AEDs) in mice seizure tests and both pharmacodynamic and pharmacokinetic interactions were noted. The present study was carried out to investigate influence of sildenafil on the threshold for 6 Hz-induced psychomotor seizures in mice. Effect of sildenafil on activity of some AEDs, i.e., phenobarbital (PB), clonazepam (CZP), ethosuximide (ETS), valproic acid (VPA), tiagabine (TGB), oxcarbazepine (OXC) and levetiracetam (LEV), in 6 Hz test was also examined. Moreover, combination of sildenafil with LEV was investigated in terms of influence on motor coordination (determined by the chimney test), muscular strength (evaluated in the grip-strength test) and long-term memory (assessed in the passive avoidance task) in mice. To determine the type of pharmacological interaction between sildenafil and LEV, free plasma and total brain concentrations of this AED were determined by LC-MS/MS method. Sildenafil at a dose ranging from 10 to 40 mg/kg statistically increased psychomotor seizure threshold in mice. Moreover, sildenafil enhanced the anticonvulsant action of all the studied AEDs in this test. Interactions between this PDE5 inhibitor and PB, CZP, ETS, TGB and OXC seem to be pharmacodynamic. Since sildenafil increased free plasma and total brain concentration of LEV, interactions between these drugs have pharmacokinetic nature. This kind of interaction was also noted between sildenafil and VPA. Neither LEV (2.32 mg/kg) nor its co-administration with sildenafil (40 mg/kg) produced any significant changes in motor coordination, muscular strength and long-term memory in mice.

Toxicological assessment of drugs that affect the endocrine system in puberty-related disorders

INTRODUCTION

Toxicologists must ensure that clinical risk-to-benefit analysis should be made both for genders and age groups, with any treatment. Puberty concerns physiological changes leading to organism's maturation. Pubertal growth disorders are increasing in last decades: besides causing physical and psychological distress, they may signal underlying endocrine-metabolic abnormalities with serious health consequences later on. Therapeutic approaches for some health conditions in childhood and adolescence are considered.

AREAS COVERED

The authors discuss how some diseases and treatments can impact pubertal growth. The authors look at particular immunological disorders such as asthma and how both the disease and treatment affects pubertal growth. They also discuss how the provision of available data can help to assess the dose-response of the drug, in these cases, and minimize the chance of side effects. The authors also discuss pediatric inflammatory bowel disease and how both the disease and treatment can mitigate the growth delay. Last, but not least, the authors discuss how the effects of the drugs used in the treatment of psychiatric disorders may accentuate endocrine issues in juvenile patients. Hyperprolactinemia induction by some antipsychotics is highlighted as an example.

EXPERT OPINION

Appropriate risk-benefit analysis of drugs prescribed during childhood and adolescence and intended to be used in the long term is required. Furthermore, future treatment strategies and safer compounds development should be supported by the knowledge of mechanisms underlying adverse side effects in pubertal growth and development.

Adverse drug reactions induced by valproic acid

Valproic acid is a widely-used first-generation antiepileptic drug, prescribed predominantly in epilepsy and psychiatric disorders. VPA has good efficacy and pharmacoeconomic profiles, as well as a relatively favorable safety profile. However, adverse drug reactions have been reported in relation with valproic acid use, either as monotherapy or polytherapy with other antiepileptic drugs or antipsychotic drugs. This systematic review discusses valproic acid adverse drug reactions, in terms of hepatotoxicity, mitochondrial toxicity, hyperammonemic encephalopathy, hypersensitivity syndrome reactions, neurological toxicity, metabolic and endocrine adverse events, and teratogenicity.

Therapeutic potential of mood stabilizers lithium and valproic acid: beyond bipolar disorder

The mood stabilizers lithium and valproic acid (VPA) are traditionally used to treat bipolar disorder (BD), a severe mental illness arising from complex interactions between genes and environment that drive deficits in cellular plasticity and resiliency. The therapeutic potential of these drugs in other central nervous system diseases is also gaining support. This article reviews the various mechanisms of action of lithium and VPA gleaned from cellular and animal models of neurologic, neurodegenerative, and neuropsychiatric disorders. Clinical evidence is included when available to provide a comprehensive perspective of the field and to acknowledge some of the limitations of these treatments. First, the review describes how action at these drugs' primary targets--glycogen synthase kinase-3 for lithium and histone deacetylases for VPA--induces the transcription and expression of neurotrophic, angiogenic, and neuroprotective proteins. Cell survival signaling cascades, oxidative stress pathways, and protein quality control mechanisms may further underlie lithium and VPA's beneficial actions. The ability of cotreatment to augment neuroprotection and enhance stem cell homing and migration is also discussed, as are microRNAs as new therapeutic targets. Finally, preclinical findings have shown that the neuroprotective benefits of these agents facilitate anti-inflammation, angiogenesis, neurogenesis, blood-brain barrier integrity, and disease-specific neuroprotection. These mechanisms can be compared with dysregulated disease mechanisms to suggest core cellular and molecular disturbances identifiable by specific risk biomarkers. Future clinical endeavors are warranted to determine the therapeutic potential of lithium and VPA across the spectrum of central nervous system diseases, with particular emphasis on a personalized medicine approach toward treating these disorders.

Sildenafil influences the anticonvulsant activity of vigabatrin and gabapentin in the timed pentylenetetrazole infusion test in mice

Sildenafil, a selective phosphodiesterase 5 (PDE5) inhibitor, has recently been reported to affect convulsant activity in some animal models of seizures and epilepsy. Moreover, its influence on the protective activity of some antiepileptic drugs (AEDs) was also noted. The aim of the present study was to investigate the effect of sildenafil on the anticonvulsant potential of gabapentin (GBP) and vigabatrin (VGB) in the timed intravenous (i.v.) pentylenetetrazole (PTZ) test in mice. The chimney test, the passive avoidance task and the grip strength test were used to estimate some possible side effects caused by the studied AEDs and their combinations with sildenafil. Total brain and free plasma concentrations of GBP and VGB were determined to evaluate the characteristics of interactions. Our studies revealed that GBP (25-100 mg/kg) increases the threshold for the forelimb tonic extension, whereas VGB raises thresholds both, for myoclonic (200-600 mg/kg) and generalized clonic (400-600 mg/kg) seizures in the used model of seizures. GBP at sub-effective dose of 12.5 mg/kg co-administered with sildenafil at doses of 10 and 20 mg/kg significantly increases the threshold for tonic seizures in the i.v. PTZ test in mice. Combination of sub-effective dose of VGB (200 mg/kg) with sildenafil at a dose of 5mg/kg also showed significant anticonvulsant activity against clonic seizures. The studied AEDs and their combinations with sildenafil did not produce any changes in the motor coordination, long-term memory and muscular strength in mice. Sildenafil did not influence total brain and free plasma concentrations of GBP and VGB. Interactions between the studied AEDs and sildenafil were pharmacodynamic in nature and for that reason they are worthy of consideration in the clinical practice.

Antiepileptic drug monotherapy versus polytherapy: pursuing seizure freedom and tolerability in adults

PURPOSE OF REVIEW

Despite the availability of many new antiepileptic drugs (AEDs), only around 50% of people with epilepsy will become seizure free on their first drug. This article explores treatment options and issues influencing whether AEDs should be substituted or combined in the remainder of the patient population.

RECENT FINDINGS

Prior to the introduction of novel AEDs, it was generally opined that combining traditional agents did not necessarily lead to an improvement in seizure control and might increase the propensity for side effects. Newer AEDs, many with different mechanisms of action, have increased the potential for polytherapy regimens, although robust data to support or refute this therapeutic strategy are sparse. It seems sensible to substitute rather than combine when the first AED produces an idiosyncratic reaction, is poorly tolerated at a low/moderate dose or shows no efficacy. Polytherapy may be preferred if the patient tolerates their first or second AED well, but with a suboptimal response, particularly when there is an identifiable anatomical substrate for the seizures. AED selection requires consideration of many factors some of which are discussed in this study.

SUMMARY

There are no definitive answers on whether to combine or substitute AEDs. Different strategies are required for different scenarios in different patients.

Cytochrome P450 enzymes in the brain: emerging evidence of biological significance

Cytochrome P450 (CYP) enzymes are responsible for the metabolism of many exogenous and endogenous compounds. CYPs are abundant in the liver and are also expressed in many extra-hepatic tissues including the brain. Although total CYP levels in the brain are much lower than in the liver, brain CYPs are concentrated near drug targets in specific regions and cell types, and can potentially have a considerable impact on local metabolism. Individual differences in brain CYP metabolism, due to inducers, inhibitors or genetic variation, can influence sensitivity and response to centrally acting drugs. Brain CYPs may also play a role in modulating brain activity, behavior, susceptibility to central nervous system diseases and treatment outcomes. This review highlights recent progress that has been made in understanding the functional significance of CYPs in the brain.