Impact of prenatal amoxicillin exposure on hippocampal development deficiency.

BACKGROUND: Amoxicillin has been widely used to treat infectious diseases during pregnancy. Current studies suggest that amoxicillin exposure during pregnancy could lead to developmental disorders in the offspring and increase the incidence of long-term complications such as asthma and kidney damage in adulthood. However, the adverse effects of prenatal amoxicillin exposure (PAmE) including administration stage, doses and courses on fetal hippocampal neurodevelopment and its function in the offspring have not been elucidated. In this study, we intend to investigate the effects of PAmE on fetal hippocampal development and its possible mechanisms. METHOD: Pregnant Kunming mice were given intragastric administration with amoxicillin at different administration stage, doses and courses, and GD (gestational day) 18 offspring hippocampus was collected for morphological and development-related functional assays, and the molecular mechanisms were explored. RESULTS: PAmE induced hippocampal hypoplasia in the offspring with suppressed hippocampal neuronal cell proliferation and impaired neuronal synaptic plasticity comparatively; hippocampal astrocyte and microglia were damaged to varying degrees. The developmental toxicity of PAmE in fetal mices varies by time, dose, and course of treatment. The most severe damage was observed in the late gestation, high dose, and multi-course dosing groups. The significant reduction either in SOX2, an essential gene in regulating neural progenitor cell proliferation, and reduction of genes related to the Wnt/ß-catenin pathway may suggest that the key role of SOX2/Wnt/ß-catenin pathway in impaired hippocampal development in the offspring due to PAmE. CONCLUSION: In this study, PAmE was found to be developmentally toxic to the hippocampus thus to induce developmental damage to various hippocampal cells; Even with current clinically safe doses, potential hippocampal damage to offspring may still present; This study provides a theoretical and experimental basis for guiding the rational usage of drugs during pregnancy and giving effectively assessment of the risk on fetal hippocampal developmental toxicity.

DPP4 regulates the inflammatory response in a rat model of febrile seizures.

Febrile seizures (FS) are the most common seizure disorders in children aged 6 months to 5 years. Children suffering from complex FS have a high risk of developing subsequent temporal lobe epilepsy (TLE). Neuroinflammation is involved in the pathogenesis of FS although the mechanism remains unknown. Our previous study using the Whole Rat Genome Oligo Microarray determined that Dipeptidyl peptidase IV (DPP4) is potentially a related gene in FS rats. In this study, we demonstrated that DPP4 expression was significantly increased at both the protein and mRNA levels after hyperthermia induction. Sitagliptin, a specific enzyme inhibitor of DPP4, remarkably attenuated the severity of seizures in FS rats, and hyperthermia-induced astrocytosis was suppressed after DPP4 inhibition. Furthermore, sitagliptin significantly decreased the levels of the inflammatory cytokines IL-1ß, TNF-α, and IL-6 but not IL-10. In addition, sitagliptin prevented NF-κB activation by decreasing phosphorylation of the p65 subunit. Taken together, our findings demonstrate that DPP4 functions as a critical regulator of neuroinflammation in hyperthermia-induced seizures and the DPP4 inhibitor may be a viable option for FS therapeutics.

Decreased Methylation Level of H3K27me3 Increases Seizure Susceptibility.

Epigenetic modifications including histone modifications are associated with seizure development and epileptogenesis; however, its underlying mechanism remains to be elucidated. Dipeptidyl peptidase 4 (DPP4) and IL6 are identified as febrile seizure (FS)-related genes using gene microarray analysis in hyperthermia prone (HP) rats. This purpose of the study focused on exploring whether epigenetic modifications marker histone H3 lysine 27 trimethylation (H3K27me3)-regulated DPP4 and IL6 expression further affected seizures development. Herein, we reported broad between-group differences in the global levels of H3K27me3 with increased seizure severity in vivo. Using chromatin immunoprecipitation (ChIP), we identified markedly decreased H3K27me3 enrichment at their promoters of DPP4 and IL6 in vivo. We further showed that hyperthermia significantly decreased protein levels of H3K27me3, increased mRNA levels of DPP4 and IL6 by decreasing H3K27me3 enrichment at their promoters of DPP4 and IL6 in vitro. Importantly, H3K27me3 loss via enhancer of zeste homolog 2 (EZH2) knockdown promoted expression of DPP4 and IL6 via the same mechanism in vitro. EZH2 knockdown also increased neuronal firing frequency in vitro and FS susceptibility in vivo companied with upregulation expression of DPP4 and IL6. Taken together, our study provided the first evidence that hyperthermia-induced decreased of H3K27me3 promoted seizure susceptibility via regulating the expression pattern of DPP4 and IL6. These findings suggested that the methylation level of H3K27me3 might be a key regulator of seizure susceptibility.

A review on the pharmacological effects of vitexin and isovitexin.

Vitexin and isovitexin are active components of many traditional Chinese medicines, and were found in various medicinal plants. Vitexin (apigenin-8-C-glucoside) has recently received increased attention due to its wide range of pharmacological effects, including but not limited to anti-oxidant, anti-cancer, anti-inflammatory, anti-hyperalgesic, and neuroprotective effects. Isovitexin (apigenin-6-C-glucoside), an isomer of vitexin, generally purified together with vitexin, also exhibits diverse biological activities. Latest research has suggested that vitexin and isovitexin could be potential substitute medicines for diversity diseases, and may be adjuvants for stubborn diseases or health products. This review summarized recent findings on various pharmacological activities and associative signalling pathways of vitexin and isovitexin to provide a reference for future research and clinical applications.

Vitexin reduces hypoxia-ischemia neonatal brain injury by the inhibition of HIF-1alpha in a rat pup model.

Previous studies have demonstrated that the early suppression of HIF-1α after hypoxia-ischemia (HI) injury provides neuroprotection. Vitexin (5, 7, 4-trihydroxyflavone-8-glucoside), an HIF-1α inhibitor, is a c-glycosylated flavone that has been identified in medicinal plants. Therefore, we hypothesized that treatment with vitexin would protect against HI brain injury. Newborn rat pups were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O2 at 37 °C). Vitexin (30, 45 or 60 mg/kg) was administered intraperitoneally at 5 min or 3 h after HI. Vitexin, administered 5 min after HI, was neuroprotective as seen by decreased infarct volume evaluated at 48 h post-HI. This neuroprotection was removed when vitexin was administered 3 h after HI. Neuronal cell death, blood-brain barrier (BBB) integrity, brain edema, HIF-1α and VEGF protein levels were evaluated using a combination of Nissl staining, IgG staining, brain water content, immunohistochemistry and Western blot at 24 and 48 h after HI. The long-term effects of vitexin were evaluated by brain atrophy measurement, Nissl staining and neurobehavioral tests. Vitexin (45 mg/kg) ameliorated brain edema, BBB disruption and neuronal cell death; Upregulation of HIF-1α by dimethyloxalylglycine (DMOG) increased the BBB permeability and brain edema compared to HI alone. Vitexin attenuated the increase in HIF-1α and VEGF. Vitexin also had long-term effects of protecting against the loss of ipsilateral brain and improveing neurobehavioral outcomes. In conclusion, our data indicate early HIF-1α inhibition with vitexin provides both acute and long-term neuroprotection in the developing brain after neonatal HI injury.

TRPV1 promotes repetitive febrile seizures by pro-inflammatory cytokines in immature brain.

Febrile seizure (FS) is the most common seizure disorder in children, and children with FS are regarded as a high risk for the eventual development of epilepsy. Brain inflammation may be implicated in the mechanism of FS. Transient receptor potential vanilloid 1 (TRPV1) is believed to act as a monitor and regulator of body temperature. The role of inflammation in synaptic plasticity mediation indicates that TRPV1 is relevant to several nervous system diseases, such as epilepsy. Here, we report a critical role for TRPV1 in a febrile seizure mouse model and reveal increased levels of pro-inflammatory factors in the immature brain. Animals were subjected to hyperthermia for 30 min, which generates seizures lasting approximately 20 min, and then were used for experiments. To invoke frequently repetitive febrile seizures, mice are exposed to hyperthermia for three times daily at an interval of 4h between every time induced seizure, and a total of 4 days to induce. Behavioral testing for febrile seizures revealed that a TRPV1 knock-out mouse model demonstrated a prolonged onset latency and a shortened duration and seizure grade of febrile seizure when compared with wild type (WT) mice. The expression levels of both TRPV1 mRNA and protein increased after a hyperthermia-induced febrile seizure in WT mice. Notably, TRPV1 activation resulted in a significant elevation in the expression of pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α and HMGB1) in the hippocampus and cortex. These data indicate that the reduction of TRPV1 expression parallels a decreased susceptibility to febrile seizures. Thus, preventative strategies might be developed for use during febrile seizures.

Role of TRPV1 in susceptibility to PTZ-induced seizure following repeated hyperthermia challenges in neonatal mice.

This study was designed to investigate the role of experimental febrile seizures in the induction of generalized clonic seizures and the involvement of heat-sensitive channel TRPV1. Pentylenetetrazol-induced clonic seizure was used as the seizure model, and Trpv1 gene knock-out and wild-type C57/BL6 mice were used as experimental subjects. Electroencephalograph and seizure behavior were recorded for the evaluation of the severity of seizures. Increased frequency of the experimental febrile seizures facilitated PTZ-induced generalized clonic seizures. Trpv1 gene deficiency decreased the properties of generalized clonic seizure. The intensity of experimental febrile seizures reduced the threshold to generalized clonic seizure, and Trpv1 gene deficiency decreased the susceptibility to PTZ-induced seizures following early-life hyperthermia challenges in mice.