J. Neurochem. (2010) 114, 386–396. Abstract Highly activated microglia and followed excessive expression of inflammatory cytokines are associated with neuroexcitotoxic injuries. We use electrophysiological techniques, ELISA, western‐blot, RT‐PCR assay and TUNEL method to explore whether over‐produced tumor necrosis factor alpha (TNFα) released from activated microglia results in neuronal injuries, and further causes apoptosis through increasing excitotoxicity of hippocampal neurons. Our data showed that kainic acid (KA) activated microglia highly expressed TNFα, mRNA and protein. KA activated microglia conditioned media ((KA‐MCM) significantly enhanced the amplitude of the population spike at rat’s hippocampal CA3 region. It also increased the Ca2+ current amplitude and density in cultured hippocampal neurons, as well as the high expression of NMDAR1, iNOS, and caspase 3 mRNA and protein at both hippocampal neurons and tissues. KA‐MCM also increased TUNEL‐positive cells in hippocampal neurons, whereas addition of anti‐TNFα to the KA‐MCM before its application significantly reduced those effects. These studies suggest that TNFα derived from KA activated microglia increases excitotoxicity of hippocampal neurons, and might induce neuronal apoptosis in vitro and in vivo.

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The association of the rs9939609 single nucleotide polymorphism in FTO gene with obesity has been extensively investigated in studies of populations of European, African, and Asian ancestry. However, inconsistent results have been reported in Asian populations, and the relationship of FTO variation and dietary behaviors has only rarely been examined in Chinese children and adolescents. The aim of this study was to assess the association of rs9939609 with obesity and dietary preferences in childhood in a Chinese population. Epidemiological data including dietary preferences were collected in interviews using survey questionnaires, and rs9939609 genotype was determined by real-time PCR. The associations of rs9939609 genotypes with obesity and dietary preferences were analyzed by multivariate logistic regression using both additive and dominant models. The results showed that subjects with a TA or AA genotype had an increased risk of obesity compared with the TT participants; the odds ratios (ORs) were 1.47 (95% CI: 1.25–1.71, P = 1.73×10−6), and 3.32 (95% CI: 2.01–5.47, P = 2.68×10−6), respectively. After adjusting for age and gender, body mass index, waist circumference, hip circumference, systolic blood pressure, diastolic blood pressure, fasting blood glucose, triglycerides, and low-density lipoprotein cholesterol were higher, and high-density lipoprotein cholesterol was lower in TA and AA participants than in those with the TT genotype. After additionally controlling for body mass index, the association remained significant only for systolic blood pressure (P = 0.005). Compared with TT participants, those with the AA genotype were more likely to prefer a meat-based diet (OR = 2.81, 95% CI: 1.52–5.21). The combined OR for obesity in participants with TA/AA genotypes and preference for a meat-based diet was 4.04 (95% CI: 2.8–5.81) compared with the TT participants who preferred a plant-based diet. These findings indicate the genetic variation of rs9939609 is associated with obesity and dietary preferences in Chinese children and adolescents.

Objective: It is known that highly activated microglia and the consequent production of inflammatory cytokines were associated with neuroexcitotoxic injuries. The present study was carried out to explore whether interleukin-1β (IL-1β), a proinflammatory cytokine produced in abundance by activated microglia, mediates increased excitability of hippocampal neurons and the related molecular mechanisms. Methods: Primary cultured microglia were activated by kainic acid (KA), and the KA-treated microglial conditioned medium (KA-MCM) was collected. KA-MCM with or without anti-rat IL-1β monoclonal neutralizing antibody was then injected into the rat in the right cerebral ventricle, or primary cultured hippocampal neurons were treated with the above-mentioned KA-MCM. The population spike amplitude changes in the CA3 region were assessed by electrophysiological recording in vivo. Western blot and RT-PCR assay were performed to investigate the expression changes of N-methyl-D-aspartate receptor subunit 1 (NMDAR1) and inducible nitric oxide synthase (iNOS) expression in hippocampal neurons. Results: Primary cultured microglia were significantly activated by KA with increased IL-1β levels. Interestingly, intracerebroventricular administration of KA-MCM to rats resulted in enhancement of population spike amplitude in the CA3 region and in upregulation of NMDAR1 and iNOS expression in the hippocampus, which was partially attenuated by anti-rat IL-1β antibody. Furthermore, the changes in NMDAR1 and iNOS expression in the rat hippocampus were verified by incubation of primary cultured hippocampal neurons with KA-MCM. Conclusion: This study provides evidence that KA-activated microglia mediate increased excitability of hippocampal neurons in vitro and in vivo and that IL-1β may be one of the main causes of this event.

Erythropoietin (EPO) suppresses epileptogenesis and limits the neuronal damage associated with recurrent seizures, but the neurocellular mechanism is unclear. Dysregulation of intracellular calcium homeostasis is a key pathogenic event leading to the progression of epileptic activity, suggesting that EPO may suppress seizures by stabilizing intracellular calcium. In this study, we examined the effects of EPO on voltage-gated Ca(2+) influx in cultured rat hippocampal neurons and population spike (PS) amplitude in kainic acid (KA)-induced rats and the mechanisms responsible. KA injection markedly increased EPO and EPO receptor expression and the amplitude of PS in the hippocampal CA3 region, evoked by perforant pathway stimulation. Intracerebroventricular injection of exogenous rat recombinant EPO reversed KA-induced PS amplitude in the hippocampal CA3 region. Similarly, rat recombinant EPO pretreatment attenuates the increased voltage-gated calcium current's (I(Ca)) amplitude and density induced by KA in cultured hippocampal neurons. In contrast, transient transfection of rat EPO small interfering RNS (siRNA) further enhanced I(Ca) amplitude and density in the presence of KA, whereas a scrambled control siRNA had no effect. Further, EPO activates the PI3K and ERK1/2 pathways in cultured hippocampal neurons, and the PI3K/Akt inhibitor LY294002 and ERK1/2 inhibitor U0126 both blocked, at least in part, the suppressive effect of exogenous EPO on KA-induced calcium currents. This study indicates that both endogenous and exogenous EPO decrease KA-sensitive calcium influx and concomitant hyperexcitability in hippocampal neurons. The results also demonstrate that the PI3K/Akt and ERK1/2 signaling pathways mediate the EPO-modulated calcium influx in KA-induced epilepsy.