ERK activation effects on GABA secretion inhibition induced by SDF-1 in hippocampal neurons of rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the effect of extracellular regulating kinase (ERK) signaling pathway on the secretion of gamma-aminobutyric acid (GABA) in cultured rat hippocampal neurons induced by stromal cell derived factor-1 (SDF-1).</p><p><b>METHODS</b>The hippocampal neurons of newborn SD rats were cultured and identified in vitro; the phosphorylation level of ERK1/2 was examined by Western blot; ELISA was used to detect the effect of PD98059, a ERK1/2 specific blocker on GABA secretion of cultured hippocampal neurons and Western blot were adopted to measure the protein expression levels of glutamate decarboxylase (GAD65/67) and gamma aminobutyric acid transporter (GAT); after blocking ERK1/2 signaling pathway with PD98059; RT-PCR was used to detect the mRNA expression levels of GAT-1 and GAD65 after treated with PD98059.</p><p><b>RESULTS</b>The levels of ERKl/2 phosphorylation were increased significantly by SDF1 acting on hippocampal neurons, and CX-CR4 receptor blocker AMD3100, could inhibit SDF-1 induced ERK1/2 activation; SDF-1 could inhibit the secretion of GABA in cultured hippocampal neurons, and ERK1/2 specific inhibitor PD98059, could partly reverse the inhibition of GABA secretion by SDF-1. The effects of SDF-1 on cultured hippocampal neurons was to decrease the mRNA genesis of glutamic acid decarboxylase GAD65 and GABA transporter GAT-1, besides, ERK inhibitor PD98059 could effectively flip the effect of SDF-1. The results of Western blot showed that SDF-1 could inhibit the protein expression of GAT-1 and GAD65/67 in hippocampal neurons and the inhibition of GAT-1 and GAD65/67 protein expression could be partially restored by ERK1/2 blocker.</p><p><b>CONCLUSION</b>SDF-1 acts on the CXCR4 of hippocampal neurons in vitro, and inhibits the expression of GAD by activating the ERK1/2 signaling pathway, and this may represent one possible pathway of GABA secretion inhibition.</p>

The change of potassium current of neural stem cells cultured in vitro from newborn rat hippocampus / 中国应用生理学杂志

<p><b>AIM</b>To observe the change of potassium current on cultured neurons differentiated from hippocampus neural stem cells of the newborn rat.</p><p><b>METHODS</b>Neural stem cells from newborn rat hippocampus were cultured in vitro and passaged continuously. Differentiation of the cell was induced by serum and removing mitogens. After differentiation cells were plated on plastic dishes and cultured for 1 d, 7 d, 14 d and 21 d. Whole-cell voltage patch clamp recording was used respectively to detect voltage-dependent K+ current.</p><p><b>RESULTS</b>After 1 d culture, no current was detected, and on the 7th d, 14th d, 21st d after differentiation, the amplitude of K+ currents was (18.077 +/- 2.789)pA/pF, (13.099 +/- 2.742)pA/pF, (34.045 +/- 8.067)pA/pF at +50 mV. The recorded K+ current included two components that could be blocked by TEA and 4-AP separately, assumed the slowly inactivating delayed rectifier K+ current (IK) and the fast inactivating transient outward K+ current (IA).</p><p><b>CONCLUSION</b>The function of potassium channels on the hippocampus neural stem cells of the newborn rat approaches mature gradually when the time of differentiation becomes longer in vitro.</p>