Investigating the role of zinc in a rat model of epilepsy

Ketogenic diet with oxyresveratrol and zinc inhibits glioblastoma and restores memory function and motor coordination

Background

To date, there is no effective cure for the highly malignant brain tumor glioblastoma (GBM). GBM is the most common, aggressive central nervous system tumor (CNS). It commonly originates in glial cells such as microglia, oligodendroglia, astrocytes, or subpopulations of cancer stem cells (CSCs). Glucose plays an important role in the, which energy metabolism of normal and cancer cells, but cancer cells exhibit an increased demand for glucose is required for their differentiation and proliferation. The main aim of this study is to explore the anti-cancer efficacy of the ketogenic diet against GBM. Also, this research focuses on the identification of the catalytic action of zinc in epigenetic modulators such as oxyresveratrol and ensures the combinatorial effect in the treatment of GBM.

Method

In this study, we have evaluated various parameters to understand the therapeutic efficacy of the treatment groups through in vivo experiments against aggressive brain tumors. Intracerebroventricular experiments were performed to induce the tumor in the animals and estimate the tumor burden and proliferative index. Followed by the Morris water maze, an open field test, and rota rod was performed to evaluate the memory and motor coordination. To understand the glucose, and ketone level modification before and after treatment, the level of glucose and ketone was analyzed. Moreover, the zinc level is assessed using flame atomic absorption spectroscopy.

Results

The results suggested that the ketogenic diet has an anti-cancer efficacy against C6-induced GBM cell lines. Also, it exerts a synergistic effect with the epigenetic modulator, oxyresveratrol, and zinc against GBM cell lines. Moreover, the treatment groups improved memory and motor coordination and modified the glucose and ketone levels to reduce the tumor burden and Ki-67 proliferative index.

Conclusion

This study revealed the therapeutic effect of the ketogenic diet along with its combination such as oxyresveratrol and zinc against the C6-induced GBM in the Wistar rats. Also, it improved memory and motor coordination and reduced tumor growth. It also modified the glucose and ketone levels in the tumor-induced animal and supported to diminish the tumor burden.

Effect of trans 4-butylcyclohexane carboxylic acid (4-BCCA) upon neurodegeneration, oxidative stress related to epileptogenesis in pilocarpine-induced status epilepticus

OBJECTIVE

4-butylcyclohexane carboxylic acid (4-BCCA), a low-affinity inhibitor of AMPA receptors at the trans-membrane domain have been suggested as potential therapeutic option for epilepsy, but its potential impact on status epilepticus and disease-modification and neurodegeneration following status epilepticus have not been investigated.

METHODS

This study established the effect of 4-BCCA along with standard antiseizure medications (ASMs) [valproate (VPA) and perampanel (PER)] in Li-pilocarpine induced status epilepticus rat model. We first established the effective dose of 4-BCCA in status epilepticus followed by an acute and long-term effect study. Assessments of neurobehaviour (by elevated plus maze and passive avoidance), neurodegeneration [by transmission electron microscopy (TEM) and immunohistochemistry in hippocampal slices], total antioxidant capacity (TAC) and neuronal loss [by neuron specific enolase (NSE) in cerebral tissue] were performed.

RESULTS

4-BCCA at 200 mg/kg. i.p. was found to be an effective dose and in comparison, to other ASMs it showed better seizure control in terms of latency and number of stage 3/4 seizures. PER group and 4-BCCA+PER showed better memory retention but without significant difference among the drug-treated groups. In TEM, 4-BCCA+PER and 4-BCCA+VPA group showed less nucleus and cytoplasmic changes. In immunohistochemistry 4-BCCA, PER and combination groups showed better neuronal viability. 4-BCCA+ PER showed higher TAC and lower NSE level.

SIGNIFICANCE

4-BCCA alone and its combination with ASMs especially perampanel in status epilepticus model in rats showed better seizure control and neuroprotection.

Parthenolide ameliorates 3-nitropropionic acid-induced Huntington's disease-like aberrations via modulating NLRP3 inflammasome, reducing microglial activation and inducing astrocyte shifting

BACKGROUND

Huntington's disease (HD) is a progressive neurodegenerative disease that causes motor, cognitive, and psychiatric abnormalities, with no satisfying disease-modifying therapy so far. 3-nitropropionic acid (3NP) induces behavioural deficits, together with biochemical and histological alterations in animals' striata that mimic HD. The role of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome in HD pathogenesis remains largely uncharacterized. Parthenolide (PTL), a naturally occurring nuclear factor kappa B (NF-κB) inhibitor, is also known to inhibit NLRP3 inflammasome. Whether PTL is beneficial in HD has not been established yet.

AIM

This study evaluated the possible neuroprotective effects of PTL against 3NP-induced behavioural abnormalities, striatal biochemical derangements, and histological aberrations.

METHODS

Male Wistar rats received PTL (0.5 mg/kg/day, i.p) for 3 weeks and 3NP (10 mg/kg/day, i.p) was administered alongside for the latter 2 weeks to induce HD. Finally, animals were subjected to open-field, Morris water maze and rotarod tests. Rat striata were examined histologically, striatal protein expression levels of glial fibrillary acidic protein (GFAP), cluster of differentiation 45 (CD45) and neuron-specific enolase (NSE) were evaluated immunohistochemically, while those of interleukin (IL)-1β, IL-18, ionized calcium-binding adapter molecule-1 (Iba1) and glutamate were determined by ELISA. Striatal nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein (Keap1), NF-κB, NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, S100 calcium-binding protein A10 (S100A10) and complement-3 (C3) were assessed by gene expression analysis.

RESULTS

PTL improved motor, locomotor, cognitive and anxiety-like behaviours, restored neuronal integrity, upregulated Nrf2, and inhibited NLRP3 inflammasome, NF-κB and microglial activation. Additionally, PTL induced astrocyte shifting towards the neuroprotective A2 phenotype.

CONCLUSION

PTL exhibits neuroprotection against 3NP-induced HD, that might be ascribed, at least in part, to its modulatory effects on Keap1/Nrf2 and NF-κB/NLRP3 inflammasome signaling.

Evaluating the serum levels of zinc, copper, magnesium, and 25-hydroxy vitamin D in children with idiopathic drug-resistant epilepsy; a cross-sectional study

BACKGROUND

Drug-resistant epilepsy is defined as failure of seizure control in spite of using 2 or 3 proper antiepileptic drugs in appropriate time. Mineral elements play important roles in neuronal function; it is believed that mineral deficiency may lead to complications through seizure management. In the present study, serum levels of zinc (Zn), copper (Cu), magnesium (Mg), calcium (Ca), and 25-hydroxy vitamin D (Vit D) in drug-resistant-epilepsy (DRE) patients were evaluated and compared with the controlled patients.

METHODS

In this cross-sectional study, epileptic patients were included and categorized into two groups of DRE and well-controlled patients. Patients' serum samples were analysed to evaluate Zn, Cu, Mg, Ca, and Vit D levels. The primary objective was comparison of serum levels of different trace elements between the groups.

RESULTS

Sixty-four epileptic children including 33 DRE and 31 well-controlled children entered the study. The DRE children showed a significantly earlier onset of disease compared to the other group (p = 0.014). Comparing the frequency of developmental delay between the groups, the results showed this complication was significantly more frequent in the DRE group (p < 0.001). Concerning serum elements, the results showed a significantly higher concentration of Zn in the well-controlled group than the DRE group (p = 0.007). On the other hand, no significant differences were observed between the groups regarding the means of Vit D, Ca, Cu, and Mg levels (p > 0.05).

CONCLUSION

The results of the present study delineated that drug-resistant epilepsy patients had earlier onset of disease and were at higher risk of neurodevelopmental delay compared with well-controlled-epilepsy patients. A significant lower serum levels of Zn were also observed in drug-resistant-epilepsy patients. This finding may suggest the role of zinc supplementation in help to better control of drug-resistant seizures, as well as, the importance of serum zinc monitoring in epileptic patients.

From zinc homeostasis to disease progression: Unveiling the neurodegenerative puzzle

Zinc is a crucial trace element in the human body, playing a role in various physiological processes such as oxidative stress, neurotransmission, protein synthesis, and DNA repair. The zinc transporters (ZnTs) family members are responsible for exporting intracellular zinc, while Zrt- and Irt-like proteins (ZIPs) are involved in importing extracellular zinc. These processes are essential for maintaining cellular zinc homeostasis. Imbalances in zinc metabolism have been linked to the development of neurodegenerative diseases. Disruptions in zinc levels can impact the survival and activity of neurons, thereby contributing to the progression of neurodegenerative diseases through mechanisms like cell apoptosis regulation, protein phase separation, ferroptosis, oxidative stress, and neuroinflammation. Therefore, conducting a systematic review of the regulatory network of zinc and investigating the relationship between zinc dysmetabolism and neurodegenerative diseases can enhance our understanding of the pathogenesis of these diseases. Additionally, it may offer new insights and approaches for the treatment of neurodegenerative diseases.

Deciphering the role of metal and non-metals in the treatment of epilepsy

Metals and non-metals have known to play a significant role in various physiological roles in the body including the central nervous system (CNS). The alterations in their concentration in the CNS leads to abnormalities in the normal functions which may lead to various neurological conditions including epilepsy. Manganese is a cofactor required for antioxidant enzymes such as Superoxide dismutase, Glutamine synthetase, etc. The accumulation of iron leads to formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) which have the potential to cause ferroptosis, one of the reasons for epileptogenesis. Zinc has biphasic response, both neurotoxic and neuroprotective, based on concentration levels in the CNS. Selenium is a main element for selenoproteins which is responsible for the regulation of oxidative state and antioxidant defence mechanism. The reduction in the phosphorous levels in the CNS is widely observed after generalised tonic clonic seizures (GTC), which can be a potential diagnostic biomarker. Copper acts in the CNS in an identical manner, i.e., by blocking both AMPA mediated and GABA mediated neuronal transmission. Magnesium blocks calcium channels in the NMDA receptor and prevents glutamatergic transmission, thus inhibiting excitotoxicity. Lithium acts as a proconvulsive agent and is used in combination with pilocarpine to induce seizures. The identified potential of metals and non-metals in epilepsy can be utilised in order to devise new adjuvant therapies for the management of epilepsy. The article summaries in depth the role of metals and non-metals in the treatment of epilepsy supported with special paragraph on author perspective on to the topic. Furthermore, an update of preclinical and clinical evidences are discussed in the review to give evidence on metal and non-metal based therapies in epilepsy.

Zinc and Central Nervous System Disorders

Zinc (Zn²⁺) is the second most abundant necessary trace element in the human body, exerting a critical role in many physiological processes such as cellular proliferation, transcription, apoptosis, growth, immunity, and wound healing. It is an essential catalyst ion for many enzymes and transcription factors. The maintenance of Zn²⁺ homeostasis is essential for the central nervous system, in which Zn²⁺ is abundantly distributed and accumulates in presynaptic vesicles. Synaptic Zn²⁺ is necessary for neural transmission, playing a pivotal role in neurogenesis, cognition, memory, and learning. Emerging data suggest that disruption of Zn²⁺ homeostasis is associated with several central nervous system disorders including Alzheimer's disease, depression, Parkinson's disease, multiple sclerosis, schizophrenia, epilepsy, and traumatic brain injury. Here, we reviewed the correlation between Zn²⁺ and these central nervous system disorders. The potential mechanisms were also included. We hope that this review can provide new clues for the prevention and treatment of nervous system disorders.

Determination of plasma transcobalamin-II and zinc levels in newly-diagnosed and long-standing grand mal epileptic patients

Background

The changes of plasma transcobalamin-II (TCII) and Zinc (Zn) Levels in epileptic patients are not clearly understood. The aim of the current study was to evaluate the plasma contents of TCII and Zn levels in newly-diagnosed epileptic seizure patients, long-standing grand mal epileptic patients following treatment with sodium valproate and healthy control group.

Methods

Thirty patients aged 36.76±12.91 years with newly-diagnosed and thirty long-standing grand mal epileptic patients aged 35.56 ±12.77 years were diagnosed based on the clinical symptoms. The control subjects were picked out from healthy individuals and matched to the patients, aged 36.30 ±12.80 years. Plasma Zn and TCN-2 was evaluated via spectrophotometry at 546 nm and 450 nm, respectively, using chimerical kits.

Results

Plasma level of TCII in the newly-diagnosed epileptic seizures patients and long-standing grand mal epileptic patients were significantly increased, compared to the healthy controls [14.89 ±3.24 and 21.84± 2.73 vs. 9.55±1.24, (n=30)], respectively. Plasma level of Zn was decreased in the newly-diagnosed epileptic seizure patients, while it was increased in long-standing grand mal epileptic patients compared to the control group [69.28± 6.41 and 80.56 ±6.12 and vs.75.80±1.59, (n=30)], respectively.

Conclusion

This study suggests that sodium valproate may disrupt the homeostatic balance of TCII and Zn, and cause abnormality of their serum level in newly-diagnosed epileptic seizure patients and long-standing grand mal epileptic patients. Further research is recommended to identify the underpinning for these changes.

The Important Role of Zinc in Neurological Diseases

Zinc is one of the most abundant metal ions in the central nervous system (CNS), where it plays a crucial role in both physiological and pathological brain functions. Zinc promotes antioxidant effects, neurogenesis, and immune system responses. From neonatal brain development to the preservation and control of adult brain function, zinc is a vital homeostatic component of the CNS. Molecularly, zinc regulates gene expression with transcription factors and activates dozens of enzymes involved in neuronal metabolism. During development and in adulthood, zinc acts as a regulator of synaptic activity and neuronal plasticity at the cellular level. There are several neurological diseases that may be affected by changes in zinc status, and these include stroke, neurodegenerative diseases, traumatic brain injuries, and depression. Accordingly, zinc deficiency may result in declines in cognition and learning and an increase in oxidative stress, while zinc accumulation may lead to neurotoxicity and neuronal cell death. In this review, we explore the mechanisms of brain zinc balance, the role of zinc in neurological diseases, and strategies affecting zinc for the prevention and treatment of these diseases.

The protective effect of zinc on morphine-induced testicular toxicity via p53 and Akt pathways: An in vitro and in vivo approach

BACKGROUND

Chronic use of morphine is associated with reproductive complications, such as hypogonadism and infertility. While the side effects of morphine have been extensively studied in the testis, much less is known regarding the effects of morphine on Sertoli cells and the effects of zinc on morphine-induced testicular injury as well as their underlying mechanisms. Therefore, the purpose of this study was to investigate the effect of morphine (alone and co-administered with zinc) on cell viability and apoptosis of the testicular (Sertoli) cells as well as the tumor suppressor p53 and phosphorylated-protein kinase B (p-Akt) protein levels in both in vitro and in vivo models.

METHODS

Cultured Sertoli cells were exposed to morphine (23 μM), zinc (8 μM), and zinc prior to morphine and their effects on Sertoli cell viability and apoptosis were investigated. Morphine (3 mg/kg) and zinc (5 mg/kg, 1 h before morphine) were also injected intraperitoneally to rats and then the apoptotic changes in the testis were evaluated.

RESULTS

Cell viability and p-Akt protein levels decreased in morphine-treated cells, while apoptosis and p53 protein expression increased in these cells. Pretreatment with zinc recovered morphine-induced apoptotic effects, as well as over-expression of p53 and down-regulation of p-Akt. These findings were supported by a subsequent animal study.

CONCLUSION

The present data indicated the protective effect of zinc against morphine-induced testicular (Sertoli) cell toxicity via p53/Akt pathways in both in vivo and in vitro models and suggested the clinical importance of zinc on infertility among chronic opioid users and addicted men.

Insights into Potential Targets for Therapeutic Intervention in Epilepsy

Epilepsy is a chronic brain disease that affects approximately 65 million people worldwide. However, despite the continuous development of antiepileptic drugs, over 30% patients with epilepsy progress to drug-resistant epilepsy. For this reason, it is a high priority objective in preclinical research to find novel therapeutic targets and to develop effective drugs that prevent or reverse the molecular mechanisms underlying epilepsy progression. Among these potential therapeutic targets, we highlight currently available information involving signaling pathways (Wnt/β-catenin, Mammalian Target of Rapamycin (mTOR) signaling and zinc signaling), enzymes (carbonic anhydrase), proteins (erythropoietin, copine 6 and complement system), channels (Transient Receptor Potential Vanilloid Type 1 (TRPV1) channel) and receptors (galanin and melatonin receptors). All of them have demonstrated a certain degree of efficacy not only in controlling seizures but also in displaying neuroprotective activity and in modifying the progression of epilepsy. Although some research with these specific targets has been done in relation with epilepsy, they have not been fully explored as potential therapeutic targets that could help address the unsolved issue of drug-resistant epilepsy and develop new antiseizure therapies for the treatment of epilepsy.

Long-Term Effects of Zinc Deficiency and Zinc Supplementation on Developmental Seizure-Induced Brain Damage and the Underlying GPR39/ZnT-3 and MBP Expression in the Hippocampus

We previously illustrated that long-term upregulated expression of ZnT-3 in the hippocampus of rats that underwent neonatal seizures was restored by pretreatment with a ketogenic diet. It was recently demonstrated that upregulated expression of ZnT-3 was associated with increased concentrations of intracellular free zinc ions in an in vitro model of glutamate-induced hippocampal neuronal excitotoxic damage. However, there is still a lack of research on the effects of different concentrations of zinc in the diet on developmental convulsive brain injury. The aim of this study was to investigate the effects of different zinc concentrations in the diet on long-term neurobehavioral and seizure thresholds following lithium chloride-pilocarpine-induced developmental seizures. Sprague-Dawley rats (postnatal day 27, P27) were randomly assigned to one of six dietary groups for 4 weeks: normal zinc control group (Control group, 44 mg/kg Zn), Zn-deficient control group (ZD group, 2.7 mg/kg Zn), Zn supplemented control group (ZS group, 246 mg/kg Zn), pilocarpine-induced seizure plus regular zinc diet group (SE group, 44 mg/kg Zn), seizure plus low-zinc diet group (SE + ZD group, 2.7 mg/kg Zn), and seizure plus high-zinc diet group (SE + ZS group, 246 mg/kg Zn). Novel object recognition and passive avoidance tests were performed on rats at P42 and P56. After routine seizure threshold detection and Timm staining procedures at P57, expression of GPR39, ZnT-3, and MBP were detected in the hippocampus by Western blot analysis. The results revealed that the Zinc-deficient diet for 4 weeks aggravated the long-term adverse effects of developmental seizures, evidenced by weight, cognition, seizure threshold and serum zinc concentrations, which were paralleled by expression changes in hippocampal GPR39 and ZnT-3. In contrast, zinc supplementation for 4 weeks significantly improved damage-related changes described above and rescued the abnormal expression of GPR39, ZnT-3, and MBP in the hippocampus. Similar alterations between the expression pattern of MBP and aberrant sprouting of mossy fibers in the hippocampus may indicate that sprouting is a secondary pathological change caused by developmental brain damage rather than the cause of epileptogenesis. Up-regulation of MBP protein levels in the high zinc diet-treated seizure group as well as the corresponding improvement of cognitive impairment and reduced hippocampal mossy fiber regenerative sprouting, may represent a compensatory mechanism for neuronal membrane damage and repair.

Zinc signaling and epilepsy

Evidence from both preclinical and clinical studies suggest the importance of zinc homeostasis in seizures/epilepsy. Undoubtedly, zinc, via modulation of a variety of targets, is necessary for maintaining the balance between neuronal excitation and inhibition, while an imbalance between excitation and inhibition underlies seizures. However, the relationship between zinc signaling and seizures/epilepsy is complex as both extracellular and intracellular zinc may produce either protective or detrimental effects. This review provides an overview of preclinical/behavioral, functional and molecular studies, as well as clinical data on the involvement of zinc in the pathophysiology and treatment of seizures/epilepsy. Furthermore, the potential of targeting elements associated with zinc signaling or homeostasis and zinc levels as a therapeutic strategy for epilepsy is discussed.

A possible significant role of zinc and GPR39 zinc sensing receptor in Alzheimer disease and epilepsy

Zinc the essential trace element, plays a significant role in the brain development and in the proper brain functions at every stage of life. Misbalance of zinc (Zn(2+)) ions in the central nervous system is involved in the pathogenesis of numerous neurodegenerative disorders such as Alzheimer's disease, Depression, and Epilepsy. In brain, Zn(2+) has been identified as a ligand, capable of activating and inhibiting the receptors including the NMDA-type glutamate receptors (NMDARs), GABAA receptors, nicotinic acetylcholine receptors (nAChRs), glycine receptors (glyR) and serotonin receptors (5-HT3). Recently GPR39 has been identified as a zinc-specific receptor, widely expressed in brain tissues including the frontal cortex, amygdala, and hippocampus. GPR39, when binding with Zn(2+) has shown promising therapeutic potentials. This review presents current knowledge regarding the role of GPR39 zinc sensing receptor in brain, with a focus on Alzheimer's disease and Epilepsy. Although the results are encouraging, further research is needed to clarify zinc and GPR39 role in the treatment of Alzheimer's disease and Epilepsy.

Homeostatic regulation of KCC2 activity by the zinc receptor mZnR/GPR39 during seizures

The aim of this study was to investigate the role of the synaptic metabotropic zinc receptor mZnR/GPR39 in physiological adaptation to epileptic seizures. We previously demonstrated that synaptic activation of mZnR/GPR39 enhances inhibitory drive in the hippocampus by upregulating neuronal K(+)/Cl(-) co-transporter 2 (KCC2) activity. Here, we first show that mZnR/GPR39 knockout (KO) adult mice have dramatically enhanced susceptibility to seizures triggered by a single intraperitoneal injection of kainic acid, when compared to wild type (WT) littermates. Kainate also substantially enhances seizure-associated gamma oscillatory activity in juvenile mZnR/GPR39 KO hippocampal slices, a phenomenon that can be reproduced in WT tissue by extracellular Zn(2+) chelation. Importantly, kainate-induced synaptic Zn(2+) release enhances surface expression and transport activity of KCC2 in WT, but not mZnR/GPR39 KO hippocampal neurons. Kainate-dependent upregulation of KCC2 requires mZnR/GPR39 activation of the Gαq/phospholipase C/extracellular regulated kinase (ERK1/2) signaling cascade. We suggest that mZnR/GPR39-dependent upregulation of KCC2 activity provides homeostatic adaptation to an excitotoxic stimulus by increasing inhibition. As such, mZnR/GPR39 may provide a novel pharmacological target for dampening epileptic seizure activity.

Zinc: indications in brain disorders

Zinc is the authoritative metal which is present in our body, and reactive zinc metal is crucial for neuronal signaling and is largely distributed within presynaptic vesicles. Zinc also plays an important role in synaptic function. At cellular level, zinc is a modulator of synaptic activity and neuronal plasticity in both development and adulthood. Different importers and transporters are involved in zinc homeostasis. ZnT-3 is a main transporter involved in zinc homeostasis in the brain. It has been found that alterations in brain zinc status have been implicated in a wide range of neurological disorders including impaired brain development and many neurodegenerative disorders such as Alzheimer's disease, and mood disorders including depression, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and prion disease. Furthermore, zinc has also been implicated in neuronal damage associated with traumatic brain injury, stroke, and seizure. Understanding the mechanisms that control brain zinc homeostasis is thus critical to the development of preventive and treatment strategies for these and other neurological disorders.

Low dose zinc supplementation beneficially affects seizure development in experimental seizure models in rats

The role of zinc in seizure models and with antiepileptic drugs sodium valproate (SV) and phenytoin (PHT) was studied using experimental models of seizures in rats. Male Wistar rats, 150-250 g were administered zinc 2, 20, and 200 mg/kg, orally for 14 days. Sixty minutes after the last dose of zinc, rats were challenged with pentylenetetrazole (PTZ, 60 mg/kg, ip) or maximal electroshock (MES, 70 mA, 0.2 s duration). In another group, SV (150/300 mg/kg, ip) or PHT (40 mg/kg, ip) was administered after 30 min of zinc administration followed by seizure challenge. Zinc pretreatment at all doses had no effect on MES seizures. In PTZ seizures, with the lowest dose used, i.e., 2 mg/kg, a protective effect was observed. Neither the protection offered by the 100 % anticonvulsant dose of SV (300 mg/kg) in PTZ seizures was affected by pre-treatment with zinc nor a combination of subanticonvulsant dose of SV (150 mg/kg) and zinc offer any statistically significant advantage over either drug alone. The combination of phenytoin with zinc had no effect on any of the parameters tested. Apart from this, chronic zinc administration hampered development of chemically (PTZ)-kindled seizures in rats. Zinc supplementation is unlikely to have any undesirable effect when used in epileptics rather it may offer advantage in epileptic and seizure prone patients.

Spatiotemporal expression of HDAC2 during the postnatal development of the rat hippocampus

BACKGROUND

Histone acetylation, which is a chromatin modification of histone tails, can dynamically regulate the expression of various genes in normal development. HDAC2 is a negative regulatory factor of acetylation and closely related to learning and memory. NSE is a nerve marker and vital for maintaining physiological functions in nervous system. Currently, few studies associated with the expression pattern of HDAC2 in postnatal rat hippocampus have been reported. This study aimed to explore the temporal and spatial expression pattern of HDAC2, helping to reveal the expression characteristics of HDAC2 during postnatal neuronal maturation.

MATERIALS AND METHODS

With NSE as a biomarker of neuronal maturation at postnatal days 1, 3, 7 and weeks 2, 4, and 8 (P1D, P3D, P7D, P2W, P4W, P8W), the expression patterns of HDAC2 in rat hippocampus were examined using real-time PCR and western blotting. Additionally, the subcellular distribution of HDAC2 was analysed by immunofluorescence.

RESULTS

We found that HDAC2 was highly expressed in the neonatal period and decreased gradually. HDAC2 expression was widely distributed in neurons of hippocampal CA1, CA3 and DG regions and gradually shifted from the nucleus to the cytoplasm during postnatal development. Altogether, the expression of HDAC2 decreased gradually with different subcellular localizations throughout development.

CONCLUSIONS

The observed results indicate that the expression levels of HDAC2 become lower and with different subcellular localizations in neurons during hippocampal neuronal maturation, suggesting the specific expression characteristics of HDAC2 might play an important role during postnatal learning-memory function and development.

Aggravation of seizure-like events by hydrogen sulfide: involvement of multiple targets that control neuronal excitability

AIMS

Epileptic seizures are well-known neurological complications following stroke, occurring in 3% of patients. However, the intrinsic correlation of seizures with stroke remains largely unknown. Hydrogen sulfide (H2 S) is a gas transmitter that may mediate cerebral ischemic injury. But the role of H2 S in seizures has not been understood yet. We examined the effect of H2 S on seizure-like events (SLEs) and underlying mechanisms.

METHODS AND RESULTS

Pentylenetetrazole (PTZ)- and pilocarpine-induced rat epileptic seizure models were tested. Low-Mg(2+) /high-K(+) - and 4-aminopyridine (4-AP)-induced epileptic seizure models were examined using patch-clamp recordings in brain slices. It was found that NaHS aggravated both PTZ- and pilocarpine-induced SLEs in rats, while both low-Mg(2+) /high-K(+) - and 4-AP-induced SLEs were also exacerbated by NaHS in brain slices, which may be due to its regulation on the voltage-gated sodium channel, N-methyl-D-aspartic acid receptor (NMDAR), and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) function. Furthermore, these effects were reversed by blocking voltage-gated sodium channel, NMDAR, and AMPAR.

CONCLUSIONS

These results suggest a pathological role of increased H2 S level in SLEs in vivo and in vitro. Enzymes that control H2 S biosynthesis could be interesting targets for antiepileptic strategies in poststroke epilepsy treatment.

Ion channels and zinc: mechanisms of neurotoxicity and neurodegeneration

Ionotropic glutamate receptors, such as NMDA, AMPA and kainate receptors, are ligand-gated ion channels that mediate much of the excitatory neurotransmission in the brain. Not only do these receptors bind glutamate, but they are also regulated by and facilitate the postsynaptic uptake of the trace metal zinc. This paper discusses the role of the excitotoxic influx and accumulation of zinc, the mechanisms responsible for its cytotoxicity, and a number of disorders of the central nervous system that have been linked to these neuronal ion channels and zinc toxicity including ischemic brain injury, traumatic brain injury, and epilepsy.

Zinc in the central nervous system: From molecules to behavior

The trace metal zinc is a biofactor that plays essential roles in the central nervous system across the lifespan from early neonatal brain development through the maintenance of brain function in adults. At the molecular level, zinc regulates gene expression through transcription factor activity and is responsible for the activity of dozens of key enzymes in neuronal metabolism. At the cellular level, zinc is a modulator of synaptic activity and neuronal plasticity in both development and adulthood. Given these key roles, it is not surprising that alterations in brain zinc status have been implicated in a wide array of neurological disorders including impaired brain development, neurodegenerative disorders such as Alzheimer's disease, and mood disorders including depression. Zinc has also been implicated in neuronal damage associated with traumatic brain injury, stroke, and seizure. Understanding the mechanisms that control brain zinc homeostasis is thus critical to the development of preventive and treatment strategies for these and other neurological disorders.