No genetic causal association between dental caries and Alzheimer's disease: a bidirectional two-sample Mendelian randomization analysis.

Background: An increasing number of observational studies have suggested an association between dental caries and Alzheimer's disease (AD). The association between dental caries and Alzheimer's disease may be mediated by confounders or reverse causality. In this study, we conducted bidirectional two-sample Mendelian randomization (MR) to estimate the bidirectional causality between dental caries and AD. Materials and Methods: Genome-wide association study (GWAS) summary statistics of dental caries were extracted from a published meta-analysis which included a total of 487,823 participants. GWAS datasets of AD and AD onset age were obtained from the FinnGen bank. A bidirectional two-sample analysis was performed to explore the causality between dental caries and AD. Results: For the dental caries-AD causality estimation, there was no significant association between dental caries and AD, neither with the AD GWASs from the FinnGen database (OR: 1.041, p = 0.874) nor with those from the International Genomics of Alzheimer's Project (OR: 1.162, p = 0.409). In addition, the genetic susceptibility to dental caries was not related to the onset age of AD. No causality existed between dental caries and early-onset AD (OR: 0.515, p = 0.302) or late-onset AD (OR: 1.329, p = 0.347). For the AD-dental caries relationship, no causality was detected by the IVW method (OR: 1.000, p = 0.717). Findings from other MR methods were consistent. The pleiotropy test and sensitivity analysis confirmed the validity of these MR results. Conclusions: In this bidirectional MR study, robust evidence to support a bidirectional causal effect between dental caries and AD from the GWAS results within large-scale European-descent populations was absent. Having dental caries would not alter the onset age of AD.

A causal relationship between leukocyte telomere length and multiple sclerosis: A Mendelian randomization study.

Objectives: Multiple sclerosis (MS) is a chronic inflammatory autoimmune and degenerative disorder of the central nervous system. Telomeres are protective structures located at the ends of linear chromosomes, and leukocyte telomere length (LTL) is closely connected with cell aging and senescence. However, the relationship between LTL and the risk of MS remains unknown. Methods: We performed a two-sample Mendelian randomization (MR) to evaluate whether LTL was causally associated with MS risk. Results: In our MR analysis, 12 LTL-related variants were selected as valid instrumental variables, and a causal relationship between LTL and MS was suggested. The risk of MS nearly doubled as the genetically predicted LTL shortened by one standard deviation (SD) under the inverse variance weighted (IVW) fixed effect model (odds ratio (OR) = 2.00, 95% confidence interval (CI): 1.52-2.62, p = 6.01e-07). Similar estimated causal effects were also observed under different MR models. The MR-Egger regression test did not reveal any evidence of directional pleiotropy (intercept = -0.005, stand error (SE) = 0.03, p = 0.87). The Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) analysis also indicated no directional pleiotropy or outliers for any LTL-related IVs (p-global test = 0.13). In addition, a leave-one-out sensitivity analysis showed similar findings, which further emphasized the validity and stability of the causal relationship. Conclusions: Our results suggest a potential causal effect of LTL on the risk of MS. Genetically predicted shorter LTL could increase the risk of MS in the European population. LTL should be noted and emphasized in the pathogenesis and treatment of MS.

Spectrum of clinical features and neuroimaging findings in acute cerebral infarction patients with unusual ipsilateral motor impairment- a series of 22 cases.

BACKGROUND: Cerebral infarction occurs when the arteries to brain are obstructed, and motor impairment contralateral to responsible lesion is commonly recognized. Few studies have profiled the characteristics of cases with ipsilateral motor impairment. We sought to characterize clinical features of patients with motor dysfunction caused by ipsilateral ischemic stroke. METHODS: We retrieved and analyzed the medical data for patients with ipsilateral cerebral infarction. Patients were regarded as having ipsilateral cerebral infarction if motor impairment is ipsilateral to recent stroke lesions. RESULTS: Only 22 patients with unusual ipsilateral cerebral infarction were included in this study. Ipsilateral limb paralysis was observed in all cases, and one case showed central facioplegia. Majority of patients with limb paralysis (90.9%, 20/22) presented with mild muscle strength deficits (MRC grading of 4 or more). Most of the patients (72.7%, 16/22) had a past history of stroke, and previous strokes were contralateral to the side of the recent stroke in 14 out of 16 patients (87.5%). No history of stroke or cerebral injury was identified in seven patients. With aspect of MRI findings, recent infarct lesions of all cases were located along the corticospinal tract. CONCLUSIONS: History of stroke plays an important role in the pathogenesis of ipsilateral motor impairment, and cortical reorganization in the unaffected hemisphere may contribute to the compensation of motor function after stroke. Besides that, some cases with first stroke may be due to impairment of ipsilateral uncrossed corticospinal fibers.

Successful treatment of reflex epilepsy with praxis induction by stimulus avoidance only.

PURPOSE: Reflex epilepsy is a type of epilepsy with seizures that are consistently triggered by a specific stimulus. Zipai is a Chinese ancient card game which has been popular in Southern China for hundreds of years. We sought to report and characterize clinical features of patients with reflex epilepsy evoked by playing Zipai. METHODS: We collected and analyzed clinical data of patients with Zipai-induced epilepsy. Patients were regarded as having Zipai-induced epilepsy if they suffered at least two seizure attack during the course of playing Zipai. Prolonged electroencephalography (EEG) and brain magnetic resonance imaging (MRI) were applied to all patients. All patients were advised to avoid watching and playing Zipai games in daily life, instead of using antiepileptic drugs. The seizure outcome was assessed during outpatient visits and by telephone contact. RESULTS: Five patients were included in this study. No spontaneous seizures occurred in all five patients. No patients had experienced myoclonic and coexistent absences with generalized tonic-clonic seizures (GTCS). All patients had normal MRI and prolonged EEG findings. All patients were advised to avoid the Zipai game, and became seizure-free without medication during the follow-up period (mean 5.4 years, range 3.5-7 years). CONCLUSION: Zipai-induced epilepsy may be an unreported subtype form of reflex epilepsy with praxis induction. Nonpharmacological conservative treatment plays a significant role in the treatment of reflex epilepsy.

IL-35 Is Involved in the Pathogenesis of Guillain-Barré Syndrome Through Its Influence on the Function of CD4+ T Cells.

CD4+ T cells and many cytokines play critical roles in the pathogenesis of Guillain-Barré Syndrome (GBS), an immune-mediated inflammatory disease. However, the role of IL-35, a novel member of the IL-12 cytokine family, in this kind of disease has not yet been elucidated. In this study, we investigated the functional changes of CD4+ T cells from GBS patients with IL-35 treatment in vitro. This study involved 21 GBS patients and an equal number of healthy controls (HCs). The results indicated that the average concentration of IL-35 in the plasma of GBS patients was lower than that of healthy controls (HCs). Increased levels of STAT1, STAT3 and STAT4 proteins and T-bet, ROR γt, IFN-γ and IL-17A mRNA were observed in CD4+ T cells from GBS patients. In contrast, the levels of STAT5 and STAT6 proteins and GATA3, Foxp3, IL-4 and TGF-ß1 mRNAs were decreased in GBS patients in comparison with those of HCs. In addition, treatment of CD4+ T cells from GBS patients with IL-35 upregulated IL-35, STAT5 and STAT6 protein and T-bet, GATA3, Foxp3, IFN-γ, IL-4, IL-17A and TGF-ß1 mRNA while inhibited levels of STAT3 and STAT4 protein and RORγt and IL-17A mRNA. These results indicate that IL-35 might play a potential role in GBS pathogenesis. Further studies are required in order to evaluate its role in GBS.

Potential roles of the RGMa-FAK-Ras pathway in hippocampal mossy fiber sprouting in the pentylenetetrazole kindling model.

Mossy fiber sprouting (MFS) is a unique feature of chronic epilepsy. However, the molecular signals underlying MFS are still unclear. The repulsive guidance molecule A (RGMa) appears to contribute to axon growth and axonal guidance, and may exert its biological effects by dephosphorylating focal adhesion kinase (FAK) at Tyr397, then regulating the activation of Ras. The objective of this study was to explore the expression patterns of RGMa, FAK (Tyr397) and Ras in epileptogenesis, and their correlation with MFS. The epileptic models were established by intraperitoneal pentylenetetrazole (PTZ) injection of Sprague­Dawley rats. At 3 days and at 1, 2, 4 and 6 weeks after the first PTZ injection, Timm staining was scored at different time points in the CA3 region of the hippocampus and dentate gyrus. The protein levels of RGMa, FAK (Tyr397) and Ras were analyzed at different time points in the CA3 region of the hippocampus using immunofluorescence, immunohistochemistry and western blot analysis. Compared with the control (saline­injected) group, the expression of RGMa in the CA3 area was significantly downregulated (P<0.05) from 3 days and still maintained the low expression at 6 weeks in the PTZ group. The expression of FAK (Tyr397) and Ras was upregulated (P<0.05) in the PTZ groups. The Timm score in the CA3 region was significantly higher than that in the control group at different time points and reached a peak at 4 weeks. In the CA3 region, no obvious distinction was observed at the different time points in the control group. To the best of our knowledge, these are the first results to indicate that the RGMa­FAK­Ras pathway may be involved in MFS and the development of temporal lobe epilepsy.

Dynamic expression patterns of ATF3 and p53 in the hippocampus of a pentylenetetrazole-induced kindling model.

Epilepsy is a common and often deleterious neurological condition. Emerging evidence has demonstrated the roles of innate immunity and the associated inflammatory processes in epilepsy. In a previous study, we found that Toll­like receptors (TLRs) are upregulated and promote mossy fiber sprouting (MFS) in an epileptic model. As downstream effectors of TLRs, the activating transcription factor 3 (ATF3) and p53 proteins were shown to be involved in neurite outgrowth. In the present study, we hypothesized that ATF3 and p53 participate in the process of epilepsy and can affect MFS. To investigate this hypothesis, we examined the expression of ATF3 and p53 in hippocampal tissues of rats kindled by pentylenetetrazole (PTZ) using immunofluorescence, immunohistochemistry and western blotting. MFS was evaluated by Timm staining in the hippocampus. Results from these experiments revealed that expression of ATF3 and p53 is significantly higher (p<0.05) in the CA3 area of the hippocampus in the PTZ-treated group compared to the control group. ATF3 expression gradually increased from 3 days to 4 weeks, peaked at 4 weeks and decreased slightly at 6 weeks in the PTZ group, while the expression of p53 was maintained at similar levels at different time­points following PTZ treatment. No obvious difference in the expression of these proteins was observed between the PTZ and the control group in the dentate gyrus (DG) area (p>0.05). The degree of MFS in the PTZ group peaked at 4 weeks and was maintained at a high level until 6 weeks post­PTZ treatment. In conclusion, ATF3 and p53 may be involved in the occurrence of seizure and play critical roles in MFS in the PTZ kindling model.

Expression of SOCSs and TLRs in the hippocampus of pentylenetetrazole kindling model.

BACKGROUND: Epilepsy is one of the most common neurological disorders, and approximately one-third of patients with epilepsy are resistant to anti-epileptic drugs (AEDs). Recent emerging evidence has demonstrated the roles of innate immunity and the associated inflammatory processes in epilepsy. Toll-like receptors (TLRs) are a type of pattern-recognition receptor that promote innate immune defense. The SOCS proteins as negative-feedback regulators in cytokine signaling are involved in the regulation of TLR-mediated immune responses. However, few studies investigating the role of TLRs and SOCSs in epilepsy have been reported. METHODS: To explore the role of innate immunity in the mechanism of epilepsy, the pentylenetetrazole (PTZ) kindling rat model was established using intraperitoneal injection of PTZ. The expression levels of TLR2, TLR4, and STAT molecules in rat hippocampi were analyzed using qRT-PCR and western blotting techniques. The expression levels of SOCS-1 and SOCS-3 in rat hippocampi were analyzed using qRT-PCR. RESULTS: Our data demonstrated that both the mRNA and protein expression of TLR2 and TLR4 were significantly upregulated in the rat hippocampus with PTZ injection, which was accompanied by an inhibition of SOCS-1 and SOCS-3 and an upregulation of STAT3. CONCLUSIONS: Our study suggested that SOCSs and TLRs contribute to the development of epilepsy which may lead to therapeutic interventions that limit epileptogenesis.

GSK-3ß may be involved in hippocampal mossy fiber sprouting in the pentylenetetrazole-kindling model.

Mossy fiber sprouting (MFS) is a pathological phenomenon that is commonly observed in temporal lobe epilepsy (TLE). However, the molecular mechanisms underlying MFS remain unclear. It has been demonstrated that the tau protein is important in the progression of MFS by the regulation of microtubule dynamics and axonal transport, with all of these functions of tau modulated by its site-specific phosphorylation. Glycogen synthase kinase-3ß (GSK-3ß) is an active kinase that regulates the phosphorylation of tau protein. Therefore, it was hypothesized that GSK-3ß contributes to MFS by phosphorylating tau protein. The aim of the present study was to determine the expression and activity of GSK-3ß at different regions in the rat hippocampus during the pentylenetetrazole (PTZ)-kindling process in order to demonstrate the possible correlation with MFS, and to investigate the involvement of GSK-3ß in epileptogenesis. Male Sprague-Dawley rats (n=180) were randomly divided into the control and PTZ-treated groups. The chronic epileptic model was established by intraperitoneal injection of PTZ and the hippocampus was observed for the presence of MFS using Timm staining. GSK-3ß mRNA, protein and activity were analyzed in various regions of the hippocampus using in situ hybridization, immunohistochemistry and immunoprecipitation followed by a kinase assay and liquid scintillation counting, respectively. MFS was observed prior to kindling and an increased distribution of Timm granules were observed in the CA3 region of the PTZ-treated rats; however, this was not demonstrated in the supragranular layer of the dentate gyrus. The expression of GSK-3ß mRNA and protein, as well as the GSK-3ß activity, increased significantly from 3 days to 4 weeks in the PTZ group, and this was correlated with the progression of MFS in the CA3 area. In addition, it was demonstrated that MFS did not result from TLE. GSK-3ß may therefore be involved in the progression of MFS and is important in epileptogenesis. An understanding of the molecular mechanisms underlying MFS may lead to the identification of a novel therapeutic target to limit epileptogenesis.

Altered expression of miR-146a in myasthenia gravis.

The purpose of this study was to analyze the expression of miR-146a in PBMCs obtained from patients with myasthenia gravis (MG) and healthy controls and to investigate the effect of the inhibition of miR-146a on the activation of AchR specific B cells obtained from mice. The expression of miR-146a levels in PBMCs obtained from patients with MG and healthy controls were determined by qRT-PCR. MiR-146a's complementary fragment, AntagomiR-146a, was synthesized as inhibitor, and the nonfunctional fragment, which has similar construction to AntagomiR-146a, was synthesized as negative control inhibitor. The expression of miR-146a, CD40, CD80 and CD86 on AchR specific B cells were analyzed by qRT-PCR and flow cytometry. Western blotting was used to detect the expression of TLR4, NF-κB and Bcl-2 .The expression of miRNA-146a in PBMCs obtained from patients with MG was significantly upregulated compared to healthy controls (P<0.01). Transfection with miR-146a inhibitor dramatically decreased expression of miR-146a, CD40, CD80, TLR4 and NF-κB on AchR specific B cells compared to mock transfected cells. We conclude that abnormal expression/regulation of miR-146a may play an important role in the regulation of AchR specific B cells and contribute to the pathogenesis of MG.

MicroRNA-based therapy: a new dimension in epilepsy treatment.

Epilepsy is a brain disorder, which is characterized by a predisposition to generate seizures that are associated with neurobiological, psychological cognitive and linguistic problems. Current treatments of epilepsy remain difficult, and antiepileptic drugs fail for some patients. Expressions of different microRNAs (miRNAs) in different brain regions are implicated in epileptogenic activity. MiRNAs are important regulators of seizure-induced neuronal death. The activation of inflammatory pathways is involved in reactive astrocytes and cells of the microglia in human temporal lobe epilepsy (TLE). MiRNAs are regulators of the innate immune response in the modulation of astrocyte-mediated inflammation. These miRNAs can possibly be used as a novel therapeutic target in the treatment of TLE. Targeting miRNA in epilepsy supports it as a feasible strategy for the treatment of epilepsy. But this powerful technique has received less attention as a potential therapeutic strategy. This is mainly because of the lack of well-defined targets in epilepsy. This review focuses on the role of miRNA in epilepsy, and recent advances in miRNA targeted epileptic therapies.

Macrophage migration inhibitory factor is necessary for the lipo-oligosaccharide-induced response by modulation of Toll-like receptor 4 in monocytes from GBS patients.

Previous studies have suggested that macrophage migration inhibitory factor (MIF) may play a critical role in the pathogenesis of Guillain-Barre syndrome (GBS); however, its definite mechanism remains unknown. In this study, we prepared the monocytes from the peripheral blood mononuclear cells (PBMCs) of GBS patients and the controls. Lipo-oligosaccharide (LOS) from Campylobacter jejuni was used as the stimulus of the monocytes in vitro and siRNA-MIF was used to explore the roles of MIF in LOS-induced response. Significantly, silencing of MIF attenuated the LOS-induced up-regulation of Toll-like receptor 4 (TLR4) and translocation of NF-кB into the nucleus; we also observed the up-regulation of IL-12p40, TNF-α, IL-6, CXCL8 and CCL5 in GBS monocytes with LOS stimulus; and siRNA-MIF overrided the effects of LOS on the production of the TNF-α, IL-6, and CXCL8. Conclusively, our study provides evidences that MIF may participate in the pathogenesis of GBS by modulating the LOS-induced response through TLR4 signaling pathway.

Possible involvement of toll-like receptors in the pathogenesis of myasthenia gravis.

Toll-like receptors (TLRs), the innate immunity components, have been demonstrated to participate in multiple autoimmune diseases. However, our knowledge of the roles of TLRs in myasthenia gravis (MG) is still scarce. In this study, we detected the mRNA expression of TLR1 to TLR10 in peripheral blood mononuclear cells (PBMCs) of MG patients and the healthy controls by quantitative real-time polymerase transcription chain reaction. Our data demonstrate that aberrant expressions of TLRs exist in the PBMCs of MG patients and of the total, expression level of TLR9 mRNA has significantly positive relation with the clinical severity of MG, which suggests that TLRs may be involved in the pathogenesis of MG.

Modulation of B cell regulatory molecules CD22 and CD72 in myasthenia gravis and multiple sclerosis.

B cell activation mediated by cluster of differentiation (CD) molecules plays an important role in B cell-related autoimmune diseases. CD22 and CD72 have been demonstrated to act as B cell inhibitory receptors in many autoimmune diseases. Activated B cells are involved in the pathogenesis of myasthenia gravis (MG) by secretion of anti-acetylcholine receptor (AchR) antibodies. However, the roles of CD22 and CD72 on B cells of MG are unknown. In this study, we detected the expression of CD22 and CD72 on B cells of MG, compared to multiple sclerosis (MS) patient controls and healthy controls by flow cytometry and quantitative real-time polymerase transcription chain reaction. Our data demonstrated that aberrant expression of CD72 exists on B cells of MG and MS patients and expression level of CD72 molecule has a significantly negative correlation with anti-AchR antibody levels in MG, which suggests that CD72 may be involved in the pathogenesis of MG and MS. There were no significant differences between study patients (MG, ocular MG, generalized MG, and MS) and healthy controls.

Pioglitazone, PPARγ agonist, attenuates experimental autoimmune neuritis.

Recent advances demonstrate peroxisome proliferator-activated receptors gamma (PPARγ) agonist, pioglitazone, as an anti-inflammatory drug. We investigated the effect of pioglitazone on experimental autoimmune neuritis (EAN) rats. Pioglitazone was given once daily (10 mg/kg) by oral gavage feeding from day 1-24 (suppressive group) and day 11-24 (therapeutic group). Pioglitazone ameliorated the clinical score of EAN, decreased expression of TNF-α, IFN-γ, and the activation of NF-κB, while increasing the expression of PPARγ and IL-4. Furthermore, we observed higher expression of PPARγ and IL-4 and lower expression of TNF-α, IFN-γ and reduced activation of NF-κB in suppressive group than those in the therapeutic group, which corresponds to lower clinical score and earlier disease recovery. Our data effectively demonstrate the anti-inflammatory properties of pioglitazone in EAN by inhibition of NF-κB signaling pathway.

Inactivation of TLR9 by a suppressive oligodeoxynucleotides can ameliorate the clinical signs of EAN.

Susceptible-strain animals immunized with P2 peptide could generate the disease of experimental autoimmune neuritis (EAN) with inflammation and demyelination of peripheral nerve. A myriad of transcription factors and inflammatory cytokines have been found to participate in this process; however, the roles of toll-like receptors (TLRs) are poorly understood in EAN. The aim of this study is to explore the role of TLR9 in the pathogenesis of EAN. The EAN was induced in Lewis rat by immunization with P2(53-78) and complete Freund's adjuvant. CpG oligodeoxynucleotides (ODN) (cODN), a suppressive ODN (sODN) and a control non-specific ODN (nODN) were respectively administered to explore the role of TLR9 in EAN both in vivo and vitro. Following immunization up to the peak phase of EAN, EAN rats inoculated with sODN had remarkably better clinical score of EAN and expressed a significantly inhibited TLR9 signaling pathway. Our study suggests that TLR9 may be involved in the pathogenesis of EAN.

Expression of Toll-like receptors 2, 4 and 9 in patients with Guillain-Barré syndrome.

OBJECTIVE: A myriad of transcription factors and inflammatory cytokines have been described to participate in the pathogenesis of Guillain-Barré syndrome (GBS). However, the innate immunity components--Toll-like receptors (TLRs)--have never been explored in this disease. We therefore investigated the expression of TLR2, 4 and 9 in the peripheral circulation of GBS patients as well as healthy controls. METHODS: Twenty-one GBS patients and 21 healthy donors participated in this study. Peripheral blood mononuclear cells were used for mRNA and protein analysis of TLR-related molecules. Also, peripheral blood mononuclear cells from different subjects were incubated with different TLR agonists and the subsequent IFN-γ secretion was determined. RESULTS: Expression of TLR2, 4 and 9 as well as their related signaling molecules were higher in GBS patients compared to healthy controls. Disability scores of GBS patients had a strong positive correlation with the high levels of expression of TLR2, 4 and 9. CONCLUSIONS: The TLR signaling pathway may be involved in the pathogenesis of GBS.

[Involvement of Cdk5/p35 and tau protein in the hippocampal mossy fiber sprouting in the PTZ kindling model].

OBJECTIVE: To observe the expression of cyclin-dependent kinase 5 (Cdk5), p35, tau protein and the activity of Cdk5 in rat hippocampus during pentylenetetrazole (PTZ) kindling process and their correlation with mossy fiber sprouting (MFS) so as to investigate the role of Cdk5/p35 in epileptogenesis. METHODS: A total of 240 healthy male SD rats were divided randomly into normal controls and pentylenetetrazole (PTZ) treatment groups. The epileptic models were established by injection of PTZ intraperitoneally. At Day 3, Weeks 1, 2, 4 & 6 after a daily injection of PTZ, Timm staining was scored in the CA3 region and dentate gyrus. At the same time, the mRNA and protein of Cdk5 and p35, total tau protein and its phosphorylation at ser202 and Cdk5 activity were analyzed in the hilus and stratum granulosum of dentate gyrus and the CA1, CA3 regions of hippocampus. The methods of in situ hybridization, immunohistochemistry, Western blot and immuno-precipitation and liquid scintillation counter were employed respectively. RESULTS: Prominent MFS was observed in area CA3 rather than the inner molecular layer in PTZ-treated rats. And the degree of MFS progressed with the development of behavioral kindled seizures. The expressions of Cdk5/p35 mRNA and protein, tau protein and its phosphorylation at Ser202 significantly increased from Day 3 to Week 4 in the PTZ treatment group. It was in accordance with the progression of MFS in area CA3. CONCLUSION: Cdk5/p35 and its substrate tau protein may be involved in MFS. Understanding the molecular mechanisms of MFS may lead to therapeutic interventions for limiting epileptogenesis.

Potential roles of Cdk5/p35 and tau protein in hippocampal mossy fiber sprouting in the PTZ kindling model.

BACKGROUND: The most well-documented synaptic reorganization associated with temporal lobe epilepsy is mossy fiber sprouting (MFS), which is believed to play a critical role in epileptogenesis. However, the molecular mechanisms underlying this phenomenon remain unclear. Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase which is found to be crucial in axon growth and synaptic plasticity. We hypothesized that Cdk5 contributed to MFS via phosphorylating its substrate tau protein, which was known to facilitate microtubule stabilization and axonal elongation. METHODS: 240 male SD rats were randomly divided into the control group and PTZ group. The epileptic models were established by intraperitoneal PTZ injection, while the control rats were injected with an equal dose of saline. At different time points, Cdk5/p35 mRNA and protein, total tau protein and its phosphorylation at Ser202 (p-tau) and Cdk5 activity were analyzed in different regions of hippocampus by in situ hybridization, immunohistochemistry, Western blot, immuno-precipitation and liquid scintillation counter. Hippocampus was also evaluated for MFS with Timm stain. RESULTS: Prominent MFS was observed in area CA3 rather than the inner molecular layer in PTZ treated rats and the degree of MFS progressed with the development of behavioral kindled seizures. The expression of Cdk5/p35 mRNA and protein, tau protein and its phosphorylation at Ser202 significantly increased from 3 days to 4 weeks in the PTZ group, which was in accordance with the progression of MFS in area CA3. CONCLUSIONS: Cdk5/p35 and its substrate tau protein may be involved in MFS. Understanding the molecular mechanisms underlying MFS may lead to therapeutic interventions that limit epileptogenesis.

Mossy fiber sprouting, hippocampal damage and spontaneous recurrent seizures in pentylenetetrazole kindling rat model.

AIM: The aim of this study was to determine the correlations among hippocampal damage, spontaneous recurrent seizures (SRS), and mossy fiber sprouting (MFS) using pentylenetetrazole (PTZ) kindling model. METHODS: Chronic epileptic model was established by administration of PTZ. Behaviour and EEG seizure activity were recorded. Rats' hippocampus were analyzed with haematoxylin and eosin (H&E) stain for histological lesions and evaluated for MFS with Timm stain. RESULTS: Prominent MFS was observed in area CA3 rather than the inner molecular layer in PTZ treated rats and the degree of MFS progressed with the development of behavioral kindled seizures. MFS preceded the occurrence of spontaneous seizures. No obvious neuronal necrosis and loss were observed in different regions of the hippocampus during kindling progression. CONCLUSION: MFS is not the outcome of SRS. Severe hippocampal damage is not required in the development of MFS and SRS.