Altered Proteins in the Hippocampus of Patients with Mesial Temporal Lobe Epilepsy

Serum biomarkers in patients with drug-resistant epilepsy: a proteomics-based analysis

Objective

To investigate the serum biomarkers in patients with drug-resistant epilepsy (DRE).

Methods

A total of 9 DRE patients and 9 controls were enrolled. Serum from DRE patients was prospectively collected and analyzed for potential serum biomarkers using TMT18-labeled proteomics. After fine quality control, bioinformatics analysis was conducted to find differentially expressed proteins. Pathway enrichment analysis identified some biological features shared by differential proteins. Protein-protein interaction (PPI) network analysis was further performed to discover the core proteins.

Results

A total of 117 serum differential proteins were found in our study, of which 44 were revised upwards and 73 downwards. The up-regulated proteins mainly include UGGT2, PDIA4, SEMG1, KIAA1191, CCT7 etc. and the down-regulated proteins mainly include ROR1, NIF3L1, ITIH4, CFP, COL11A2 etc. Pathway enrichment analysis identified that the upregulated proteins were mainly enriched in processes such as immune response, extracellular exosome, serine-type endopeptidase activity and complement and coagulation cascades, and the down-regulated proteins were enriched in signal transduction, extracellular exosome, zinc/calcium ion binding and metabolic pathways. PPI network analysis revealed that the core proteins nodes include PRDX6, CAT, PRDX2, SOD1, PARK7, GSR, TXN, ANXA1, HINT1, and S100A8 etc.

Conclusion

The discovery of these differential proteins enriched our understanding of serum biomarkers in patients with DRE and potentially provides guidance for future targeted therapy.

Mass Spectrometry as a Quantitative Proteomic Analysis Tool for the Search for Temporal Lobe Epilepsy Biomarkers: A Systematic Review

Temporal lobe epilepsy (TLE) is the most common form of epilepsy in adults. Tissue reorganization at the site of the epileptogenic focus is accompanied by changes in the expression patterns of protein molecules. The study of mRNA and its corresponding proteins is crucial for understanding the pathogenesis of the disease. Protein expression profiles do not always directly correlate with the levels of their transcripts; therefore, it is protein profiling that is no less important for understanding the molecular mechanisms and biological processes of TLE. The study and annotation of proteins that are statistically significantly different in patients with TLE is an approach to search for biomarkers of this disease, various stages of its development, as well as a method for searching for specific targets for the development of a further therapeutic strategy. When writing a systematic review, the following aggregators of scientific journals were used: MDPI, PubMed, ScienceDirect, Springer, and Web of Science. Scientific articles were searched using the following keywords: "proteomic", "mass-spectrometry", "protein expression", "temporal lobe epilepsy", and "biomarkers". Publications from 2003 to the present have been analyzed. Studies of brain tissues, experimental models of epilepsy, as well as biological fluids, were analyzed. For each of the groups, aberrantly expressed proteins found in various studies were isolated. Most of the studies omitted important characteristics of the studied patients, such as: duration of illness, type and response to therapy, gender, etc. Proteins that overlap across different tissue types and different studies have been highlighted: DPYSL, SYT1, STMN1, APOE, NME1, and others. The most common biological processes for them were the positive regulation of neurofibrillary tangle assembly, the regulation of amyloid fibril formation, lipoprotein catabolic process, the positive regulation of vesicle fusion, the positive regulation of oxidative stress-induced intrinsic apoptotic signaling pathway, removal of superoxide radicals, axon extension, and the regulation of actin filament depolymerization. MS-based proteomic profiling for a relevant study must accept a number of limitations, the most important of which is the need to compare different types of neurological and, in particular, epileptic disorders. Such a criterion could increase the specificity of the search work and, in the future, lead to the discovery of biomarkers for a particular disease.

Identification of immune cells infiltrating in hippocampus and key genes associated with Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent cause of dementia and is primarily associated with memory impairment and cognitive decline, but the etiology of AD has not been elucidated. In recent years, evidence has shown that immune cells play critical roles in AD pathology. In the current study, we collected the transcriptomic data of the hippocampus from gene expression omnibus database, and investigated the effect of immune cell infiltration in the hippocampus on AD, and analyzed the key genes that influence the pathogenesis of AD patients. The results revealed that the relative abundance of immune cells in the hippocampus of AD patients was altered. Of all given 28 kinds of immune cells, monocytes were the important immune cell associated with AD. We identified 4 key genes associated with both AD and monocytes, including KDELR1, SPTAN1, CDC16 and RBBP6, and they differentially expressed in 5XFAD mice and WT mice. The logistic regression and random forest models based on the 4 key genes could effectively distinguish AD from healthy samples. Our research provided a new perspective on immunotherapy for AD patients.

Proteomic and Bioinformatic Tools to Identify Potential Hub Proteins in the Audiogenic Seizure-Prone Hamster GASH/Sal

The GASH/Sal (Genetic Audiogenic Seizure Hamster, Salamanca) is a model of audiogenic seizures with the epileptogenic focus localized in the inferior colliculus (IC). The sound-induced seizures exhibit a short latency (7–9 s), which implies innate protein disturbances in the IC as a basis for seizure susceptibility and generation. Here, we aim to study the protein profile in the GASH/Sal IC in comparison to controls. Protein samples from the IC were processed for enzymatic digestion and then analyzed by mass spectrometry in Data-Independent Acquisition mode. After identifying the proteins using the UniProt database, we selected those with differential expression and performed ontological analyses, as well as gene-protein interaction studies using bioinformatics tools. We identified 5254 proteins; among them, 184 were differentially expressed proteins (DEPs), with 126 upregulated and 58 downregulated proteins, and 10 of the DEPs directly related to epilepsy. Moreover, 12 and 7 proteins were uniquely found in the GASH/Sal or the control. The results indicated a protein profile alteration in the epileptogenic nucleus that might underlie the inborn occurring audiogenic seizures in the GASH/Sal model. In summary, this study supports the use of bioinformatics methods in proteomics to delve into the relationship between molecular-level protein mechanisms and the pathobiology of rodent models of audiogenic seizures.

Predicted molecules and signaling pathways for regulating seizures in the hippocampus in lithium-pilocarpine induced acute epileptic rats: A proteomics study

Seizures in rodent models that are induced by lithium-pilocarpine mimic human seizures in a highly isomorphic manner. The hippocampus is a brain region that generates and spreads seizures. In order to understand the early phases of seizure events occurring in the hippocampus, global protein expression levels in the hippocampus on day 1 and day 3 were analyzed in lithium-pilocarpine induced acute epileptic rat models using a tandem mass tag-based proteomic approach. Our results showed that differentially expressed proteins were likely to be enhanced rather than prohibited in modulating seizure activity on days 1 and 3 in lithium-pilocarpine induced seizure rats. The differentially regulated proteins differed on days 1 and 3 in the seizure rats, indicating that different molecules and pathways are involved in seizure events occurring from day 1 to day 3 following lithium-pilocarpine administration. In regard to subcellular distribution, the results suggest that post-seizure cellular function in the hippocampus is possibly regulated in a differential manner on seizure progression. Gene ontology annotation results showed that, on day 1 following lithium-pilocarpine administration, it is likely necessary to regulate macromolecular complex assembly, and cell death, while on day 3, it may be necessary to modulate protein metabolic process, cytoplasm, and protein binding. Protein metabolic process rather than macromolecular complex assembly and cell death were affected on day 3 following lithium-pilocarpine administration. The extracellular matrix, receptors, and the constitution of plasma membranes were altered most strongly in the development of seizure events. In a KEGG pathway enrichment cluster analysis, the signaling pathways identified were relevant to sustained angiogenesis and evading apoptosis, and complement and coagulation cascades. On day 3, pathways relevant to Huntington’s disease, and tumor necrosis factor signaling were most prevalent. These results suggest that seizure events occurring in day 1 modulate macromolecular complex assembly and cell death, and in day 3 modulate biological protein metabolic process. In summary, our study found limited evidence for ongoing seizure events in the hippocampus of lithium-pilocarpine induced animal models; nevertheless, evaluating the global differential expression of proteins and their impacts on bio-function may offer new perspectives for studying epileptogenesis in the future.

Longitudinal neurodevelopmental profile of a pediatric patient with de novo SPTAN1, epilepsy, and left hippocampal sclerosis

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We present the first longitudinal study of neuropsychological functioning in a pediatric patient with SPTAN1.

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To our knowledge we report the first case of SPTAN1 heterozygosity in a patient with MTLE due to HS.

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This case is the first to show that lisdexamfetamine dimesylate improved attention, behavior, and school performance in a patient with heterozygous SPTAN1 variant.

Pathogenic variants in SPTAN1 result in abnormal neurodevelopment but limited information is available on the spectrum of neurodevelopmental profiles associated with variations in this gene. We present novel data collected at two time points over a three-year period in a nine-year-old patient with heterozygous de novo SPTAN1 variant, drug-resistant epilepsy, and left hippocampal sclerosis. Across evaluations, our patient’s performance was highly variable, ranging from below age expectation to within age-expected range. The patient exhibited relative cognitive strengths at both time points on verbal-expressive tasks. Weaknesses were seen in her attention, executive function, psychomotor processing speed, fine motor, visual-motor integration, and social skills. Memory findings were consistent those associated with left hippocampal sclerosis. Evaluations resulted in diagnoses including attention deficit hyperactivity disorder and autism spectrum disorder.

Multi-omic strategies applied to the study of pharmacoresistance in mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy in adults, and hippocampal sclerosis (HS) is a frequent histopathological feature in patients with MTLE. Pharmacoresistance is present in at least one-third of patients with MTLE with HS (MTLE+HS). Several hypotheses have been proposed to explain the mechanisms of pharmacoresistance in epilepsy, including the effect of genetic and molecular factors. In recent years, the increased knowledge generated by high-throughput omic technologies has significantly improved the power of molecular genetic studies to discover new mechanisms leading to disease and response to treatment. In this review, we present and discuss the contribution of different omic modalities to understand the basic mechanisms determining pharmacoresistance in patients with MTLE+HS. We provide an overview and a critical discussion of the findings, limitations, new approaches, and future directions of these studies to improve the understanding of pharmacoresistance in MTLE+HS. However, it is important to point out that, as with other complex traits, pharmacoresistance to anti-seizure medications is likely a multifactorial condition in which gene-gene and gene-environment interactions play an important role. Thus, studies using multidimensional approaches are more likely to unravel these intricate biological processes.

Imbalance of Systemic Redox Biomarkers in Children with Epilepsy: Role of Ferroptosis

To assess if ferroptosis, a new type of programmed cell death accompanied by iron accumulation, lipid peroxidation, and glutathione depletion, occurs in children with epilepsy, and in order to identify a panel of biomarkers useful for patient stratification and innovative-targeted therapies, we measured ferroptosis biomarkers in blood from 83 unrelated children with a clinical diagnosis of epilepsy and 44 age-matched controls. We found a marked dysregulation of three ferroptosis key markers: a consistent increase of 4-hydroxy-2-nonenal (4-HNE), the main by-product of lipid peroxidation, a significant decrease of glutathione (GSH) levels, and a partial inactivation of the enzyme glutathione peroxidase 4 (GPX4), the mediator of lipid peroxides detoxification. Furthermore, we found a significant increase of NAPDH oxidase 2 (NOX2) in the blood of children, supporting this enzyme as a primary source of reactive oxygen species (ROS) in epilepsy. Additionally, since the nuclear factor erythroid 2-related factor 2 (NRF2) induction protects the brain from epileptic seizure damage, we also evaluated the NRF2 expression in the blood of children. The antioxidant and anti-inflammatory transcription factor was activated in patients, although not enough to re-establish a correct redox homeostasis for counteracting ferroptosis. Ferroptosis-mediated oxidative damage has been proposed as an emergent mechanism underlying the pathogenesis of epilepsy. Overall, our study confirms a crucial role for ferroptosis in epilepsy, leading to the identification of a panel of biomarkers useful to find new therapeutic targets. Developing innovative drugs, which act by inhibiting the ferroptosis signaling axis, may represent a promising strategy for new anti-seizure medications.

Proteomic differences in the hippocampus and cortex of epilepsy brain tissue

Epilepsy is a common neurological disorder affecting over 70 million people worldwide, with a high rate of pharmaco-resistance, diverse comorbidities including progressive cognitive and behavioural disorders, and increased mortality from direct (e.g. sudden unexpected death in epilepsy, accidents, drowning) or indirect effects of seizures and therapies. Extensive research with animal models and human studies provides limited insights into the mechanisms underlying seizures and epileptogenesis, and these have not translated into significant reductions in pharmaco-resistance, morbidities or mortality. To help define changes in molecular signalling networks associated with seizures in epilepsy with a broad range of aetiologies, we examined the proteome of brain samples from epilepsy and control cases. Label-free quantitative mass spectrometry was performed on the hippocampal cornu ammonis 1-3 region (CA1-3), frontal cortex and dentate gyrus microdissected from epilepsy and control cases (n = 14/group). Epilepsy cases had significant differences in the expression of 777 proteins in the hippocampal CA1 - 3 region, 296 proteins in the frontal cortex and 49 proteins in the dentate gyrus in comparison to control cases. Network analysis showed that proteins involved in protein synthesis, mitochondrial function, G-protein signalling and synaptic plasticity were particularly altered in epilepsy. While protein differences were most pronounced in the hippocampus, similar changes were observed in other brain regions indicating broad proteomic abnormalities in epilepsy. Among the most significantly altered proteins, G-protein subunit beta 1 (GNB1) was one of the most significantly decreased proteins in epilepsy in all regions studied, highlighting the importance of G-protein subunit signalling and G-protein-coupled receptors in epilepsy. Our results provide insights into common molecular mechanisms underlying epilepsy across various aetiologies, which may allow for novel targeted therapeutic strategies.

iTRAQ-Based Proteomic Analysis of Dentate Gyrus in Temporal Lobe Epilepsy With Hippocampal Sclerosis

Temporal lobe epilepsy (TLE) is the most frequent type of focal epilepsy in adults, typically resistant to pharmacological treatment, and mostly presents with cognitive impairment and psychiatric comorbidities. The most common neuropathological hallmark in TLE patients is hippocampal sclerosis (HS). However, the underlying molecular mechanisms involved remain poorly characterized. The dentate gyrus (DG), one specific hippocampal subarea, structural and functional changes imply a key involvement of the DG in the development of TLE. In this study, a isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic technique was performed for the analysis of hippocampal DG obtained from patients with TLE-HS compared to control samples obtained from autopsy. Our proteomic data identified 5,583 proteins, of which 82 proteins were upregulated and 90 proteins were downregulated. Bioinformatics analysis indicated that differentially expressed proteins were enriched in "synaptic vesicle," "mitochondrion," "cell-cell adhesion," "regulation of synaptic plasticity," "ATP binding," and "oxidative phosphorylation." Protein-protein interaction network analysis found a pivotal module of 10 proteins that were related to "oxidative phosphorylation." This study has investigated proteomic alterations in the DG region of TLE-HS patients, and paved the way for the better understanding of epileptogenesis mechanisms and future therapeutic intervention.

Pro-inflammatory cytokines, but not brain- and extracellular matrix-derived proteins, are increased in the plasma following electrically induced kindling of seizures

Background

The aim of the study was to evaluate the brain-derived proteins, extracellular matrix-derived protein and cytokines as potential peripheral biomarkers of different susceptibility to seizure development in an animal model of epilepsy evoked by chronic focal electrical stimulation of the brain.

Methods

The plasma levels of IL-1β (interleukin 1β), IL-6 (interleukin 6), UCH-L1 (ubiquitin C-terminal hydrolase 1), MMP-9 (matrix metalloproteinase 9), and GFAP (glial fibrillary acidic protein) were assessed. The peripheral concentrations of the selected proteins were analyzed according to the status of kindling and seizure severity parameters. In our study, increased concentrations of plasma IL-1β and IL-6 were observed in rats subjected to hippocampal kindling compared to sham-operated rats.

Results

Animals that developed tonic–clonic seizures after the last stimulation had higher plasma concentrations of IL-1β and IL-6 than sham-operated rats and rats that did not develop seizure. Elevated levels of IL-1β and IL-6 were observed in rats that presented more severe seizures after the last five stimulations compared to sham-operated animals. A correlation between plasma IL-1β and IL-6 concentrations was also found. On the other hand, the plasma levels of the brain-derived proteins UCH-L1, MMP-9, and GFAP were unaffected by kindling status and seizure severity parameters.

Conclusions

The plasma concentrations of IL-1β and IL-6 may have potential utility as peripheral biomarkers of immune system activation in the course of epilepsy and translational potential for future clinical use. Surprisingly, markers of cell and nerve ending damage (GFAP, UCH-L1 and MMP-9) may have limited utility.

Adaptation of two-dimensional electrophoresis for muscle tissue analysis

It is important to understand the molecular mechanisms that take place in muscle tissues and to predict meat quality characteristics. One of the most popular methods is two-dimensional electrophoresis, which allows us to visualize, share and identify different molecules, including meat proteins. However, the standard conditions of this method are not universal for all types of raw material, so the authors suggest a new variation of two-dimensional electrophoresis for muscle tissue analysis. Samples were tested by the classical version of isoelectric focusing (cathode buffer in the top and anode buffer in the bottom chamber of the electrophoresis cell) and its variation (anode buffer in the top and cathode buffer in the bottom chamber of the electrophoresis cell). Next, extruded gels were incubated in two different buffer systems: the first was equilibration buffer I (6 M urea, 20% w/v glycerol, 2% w/v SDS and 1% w/v Ditiothreitol in 375 mM Tris-HCl buffer, pH 8.8) followed by equilibration buffer II (6 M urea, 20% w/v glycerol, 2% w/v SDS and 4% w/v iodoacetamide in 375 mM Tris-HCl buffer pH 8.8 and the second, buffer А, consisting of 5 M urea, 2% w/v SDS, 5% v/v mercaptoethanol, 62.5 mM Tris-HCl buffer, pH 6.8 and 0.01% w/v bromophenol blue. Electrophoretic studies of muscle tissue revealed the best protein separation after changing the direction of the current (authors' variation), while no differences were detected after changing incubation buffers.

Pilocarpine Induced Behavioral and Biochemical Alterations in Chronic Seizure-Like Condition in Adult Zebrafish

Epilepsy is a devastating neurological condition exhibited by repeated spontaneous and unpredictable seizures afflicting around 70 million people globally. The basic pathophysiology of epileptic seizures is still elusive, reflecting an extensive need for further research. Developing a novel animal model is crucial in understanding disease mechanisms as well as in assessing the therapeutic target. Most of the pre-clinical epilepsy research has been focused on rodents. Nevertheless, zebrafish disease models are relevant to human disease pathophysiology hence are gaining increased attention nowadays. The current study for the very first time developed a pilocarpine-induced chronic seizure-like condition in adult zebrafish and investigated the modulation in several neuroinflammatory genes and neurotransmitters after pilocarpine exposures. Seizure score analysis suggests that compared to a single dose, repeated dose pilocarpine produces chronic seizure-like effects maintaining an average seizure score of above 2 each day for a minimum of 10 days. Compared to the single dose pilocarpine treated group, there was increased mRNA expression of HMGB1, TLR4, TNF-α, IL-1, BDNF, CREB-1, and NPY; whereas decreased expression of NF-κB was upon the repeated dose of pilocarpine administration. In addition, the epileptic group demonstrates modulation in neurotransmitters levels such as GABA, Glutamate, and Acetylcholine. Moreover, proteomic profiling of the zebrafish brain from the normal and epileptic groups from LCMS/MS quantification detected 77 and 13 proteins in the normal and epileptic group respectively. Summing up, the current investigation depicted that chemically induced seizures in zebrafish demonstrated behavioral and molecular alterations similar to classical rodent seizure models suggesting the usability of adult zebrafish as a robust model to investigate epileptic seizures.

Granule Cell Dispersion in Human Temporal Lobe Epilepsy: Proteomics Investigation of Neurodevelopmental Migratory Pathways

Granule cell dispersion (GCD) is a common pathological feature observed in the hippocampus of patients with Mesial Temporal Lobe Epilepsy (MTLE). Pathomechanisms underlying GCD remain to be elucidated, but one hypothesis proposes aberrant reactivation of neurodevelopmental migratory pathways, possibly triggered by febrile seizures. This study aims to compare the proteomes of basal and dispersed granule cells in the hippocampus of eight MTLE patients with GCD to identify proteins that may mediate GCD in MTLE. Quantitative proteomics identified 1,882 proteins, of which 29% were found in basal granule cells only, 17% in dispersed only and 54% in both samples. Bioinformatics analyses revealed upregulated proteins in dispersed samples were involved in developmental cellular migratory processes, including cytoskeletal remodeling, axon guidance and signaling by Ras homologous (Rho) family of GTPases (P < 0.01). The expression of two Rho GTPases, RhoA and Rac1, was subsequently explored in immunohistochemical and in situ hybridization studies involving eighteen MTLE cases with or without GCD, and three normal post mortem cases. In cases with GCD, most dispersed granule cells in the outer-granular and molecular layers have an elongated soma and bipolar processes, with intense RhoA immunolabeling at opposite poles of the cell soma, while most granule cells in the basal granule cell layer were devoid of RhoA. A higher percentage of cells expressing RhoA was observed in cases with GCD than without GCD (P < 0.004). In GCD cases, the percentage of cells expressing RhoA was significantly higher in the inner molecular layer than the granule cell layer (P < 0.026), supporting proteomic findings. In situ hybridization studies using probes against RHOA and RAC1 mRNAs revealed fine peri- and nuclear puncta in granule cells of all cases. The density of cells expressing RHOA mRNAs was significantly higher in the inner molecular layer of cases with GCD than without GCD (P = 0.05). In summary, our study has found limited evidence for ongoing adult neurogenesis in the hippocampus of patients with MTLE, but evidence of differential dysmaturation between dispersed and basal granule cells has been demonstrated, and elevated expression of Rho GTPases in dispersed granule cells may contribute to the pathomechanisms underpinning GCD in MTLE.

Phosphoproteomic analysis reveals Akt isoform-specific regulation of cytoskeleton proteins in human temporal lobe epilepsy with hippocampal sclerosis

Akt is one of the most important downstream effectors of phosphatidylinositol 3-kinase/mTOR pathway. Hyperactivation and expression of this pathway are seen in a variety of neurological disorders including human temporal lobe epilepsy with hippocampal sclerosis (TLE-HS). Nevertheless, the expression and activation profiles of the Akt isoforms, Akt1, Akt2, and Akt3 and their functional roles in human TLE-HS have not been studied. We examined the protein expression and activation (phosphorylation) patterns of Akt and its isoforms in human hippocampal tissue from TLE and non-TLE patients. A phosphoproteomic approach followed by interactome analysis of each Akt isoform was used to understand protein-protein interactions and their role in TLE-HS pathology. Our results demonstrated activation of the Akt/mTOR pathway as well as activation of Akt downstream substrates like GSK3β, mTOR, and S6 in TLE-HS samples. Akt1 isoform levels were significantly increased in the TLE-HS samples as compared to the non-TLE samples. Most importantly, different isoforms were activated in different TLE-HS samples, Akt2 was activated in three samples, Akt2 and Akt1 were simultaneously activated in one sample and Akt3 was activated in two samples. Our phosphoproteomic screen across six TLE-HS samples identified 183 proteins phosphorylated by Akt isoforms, 29 of these proteins belong to cytoskeletal modification. Also, we were able to identify proteins of several other classes involved in glycolysis, neuronal development, protein folding and excitatory amino acid transport functions as Akt substrates. Taken together, our data offer clues to understand the role of Akt and its isoforms in underlying the pathology of TLE-HS and further, modulation of Akt/mTOR pathway using Akt isoforms specific inhibitors may offer a new therapeutic window for treatment of human TLE-HS.

The Interplay between the Endocannabinoid System, Epilepsy and Cannabinoids

Epilepsy is a neurological disorder that affects approximately 50 million people worldwide. There is currently no definitive epilepsy cure. However, in recent years, medicinal cannabis has been successfully trialed as an effective treatment for managing epileptic symptoms, but whose mechanisms of action are largely unknown. Lately, there has been a focus on neuroinflammation as an important factor in the pathology of many epileptic disorders. In this literature review, we consider the links that have been identified between epilepsy, neuroinflammation, the endocannabinoid system (ECS), and how cannabinoids may be potent alternatives to more conventional pharmacological therapies. We review the research that demonstrates how the ECS can contribute to neuroinflammation, and could therefore be modulated by cannabinoids to potentially reduce the incidence and severity of seizures. In particular, the cannabinoid cannabidiol has been reported to have anti-convulsant and anti-inflammatory properties, and it shows promise for epilepsy treatment. There are a multitude of signaling pathways that involve endocannabinoids, eicosanoids, and associated receptors by which cannabinoids could potentially exert their therapeutic effects. Further research is needed to better characterize these pathways, and consequently improve the application and regulation of medicinal cannabis.

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.