Morphological approach to the photo signal transduction pathway of the circadian clock

点击翻译按钮获取中文摘要

We investigated the photo signal transduction pathway in the suprachiasmatic nucleus (SCN), the mammalian circadian centers. By using in situ hybridization technique, we examined the localization of vasoactive intestinal peptide (VIP) mRNA and VPAC2 mRNA (one of the VIP receptors)-expressing neurons in the rat SCN. We found that VIP mRNA was strongly expressed in the ventrolateral SCN (VLSCN). In contrast, VPAC2 mRNA was strongly expressed in the dorsomedial SCN (DMSCN). Moreover, to investigate regional response to VIP, VIP administration to the SCN slice culture after isolation of DM from VL by a knife showed the large phase shift in only separating-DM. It is highly probable that VLSCN regulate the phase of DMSCN by VIP-VPAC2R. The findings suggest that VIP acting via the VPAC2 receptor is implicated as a key signaling pathway from VLSCN to DMSCN.