Biological And Biochemical Characterization Of Sigma Rec

该项目描述了sigma-1受体（Sig-1 R）的生物化学和药理学特性。Sig-1 R是位于内质网（ER）的单跨膜蛋白，可结合神经类固醇和某些抗抑郁药。已知抗抑郁药通过脑源性神经营养因子（BDNF）发挥作用，但确切的分子机制仍不清楚。BDNF可通过磷脂酶-γ（PLC-gamma）/三磷酸肌醇（IP 3）/Ca ~（2+）途径增强培养的皮层神经元兴奋性神经递质传递。因此，首先检查用抗抑郁药预处理对通过PLC-γ）/IP 3/Ca 2+途径的BDNF信号传导的可能影响。此外，由于PLC-γ/IP 3/Ca 2+通路被我们证明是由Sig-1 R调节的，我们检查了抗抑郁药刺激的BDNF信号传导是否由Sig-1 R调节。我们发现，BDNF刺激的PLC-γ激活和随后的细胞内Ca 2+（[Ca 2 +]i）的增加被加强与丙咪嗪或氟伏沙明预处理，所以是BDNF诱导的谷氨酸释放。此外，观察到丙咪嗪预处理后PLC-γ和TrkB（BDNF受体）之间的相互作用增强。有趣的是，BD 1047（一种有效的Sig-1 R拮抗剂）阻断了丙咪嗪依赖性增强作用，抑制了BDNF诱导的PLC-γ激活和谷氨酸释放。相反，过度表达Sig-1 R本身，没有抗抑郁药预处理，增强BDNF诱导的PLC-γ激活和谷氨酸释放。这些结果表明，抗抑郁药预处理选择性地增强BDNF信号转导的PLC-γ/IP 3/Ca 2+途径通过Sig-1 R，和Sig-1 R在BDNF信号转导导致谷氨酸释放中起重要作用。因此，我们的研究结果表明，抗抑郁药可能发挥其临床效果，通过增强BDNF信号转导通过过度表达的Sig-1 R。

This project delineates biochemical and pharmacological properties of sigma-1 receptors (Sig-1R). Sig-1R are one-transmembrane proteins at the endoplasmic reticulum (ER) that bind neurosteroids and certain antidepressants. Antidepressants have been known to exert their actions via brain-derived neurotrophic factor (BDNF) but the exact molecular mechanism remains unknown. BDNF can reinforce excitatory glutamatergic transmission in cultured cortical neurons via the phospholipase-gamma (PLC-gamma)/inositol 1,4,5-trisphosphate (IP3)/Ca2+ pathway. Therefore, the possible effects of pretreatment with antidepressants on the BDNF signaling through the PLC-gamma)/IP3/Ca2+ pathway was examined first. Furthermore, because the PLC-gamma/IP3/Ca2+ pathway is shown by us to be regulated by Sig-1R, we examined whether the BDNF signaling stimulated by antidepressants is modulated by Sig-1R. We found that the BDNF-stimulated PLC-gamma activation and the ensued increase in intracellular Ca2+ ([Ca2+]i) were potentiated by pretreatment with imipramine or fluvoxamine, so was the BDNF-induced glutamate release. Furthermore, enhancement of the interaction between PLC-gamma and TrkB (receptor for BDNF) after imipramine pretreatment was observed. Interestingly, BD1047, a potent Sig-1R antagonist, blocked the imipramine-dependent potentiation on the BDNF-induced PLC-gamma activation and glutamate release. In contrast, overexpression of Sig-1R per se, without antidepressant pretreatment, enhances BDNF-induced PLC-gamma activation and glutamate release. These results suggest that antidepressant pretreatment selectively enhance the BDNF signaling on the PLC-gamma/IP3/Ca2+ pathway via Sig-1R, and that Sig-1R plays an important role in BDNF signaling leading to glutamate release. Thus, our results suggest that antidepressants may exert their clinical effects by potentiating BDNF signaling via the overexpression of Sig-1R.