[Distribution of peptidergic neurons in the rat suprachiasmatic nucleus].

The distribution of the peptidergic neurons in the suprachiasmatic nucleus(SCN) in five adult male SD rats was examined by multi-immunolabelling for vasoactive intestinal polypeptide(VIP), arginine vasopressin (AVP) and somatostatin(SOM). The immunoreactions were visualized with an Elite ABC Kit(Vector Lab). The substrates in the peroxidase reaction were diaminobenzidine(DAB), tetramethylbenzidine(TMB) and 4-chloro-1-naphtol. The results showed that the differences in distribution and population of VIP-, AVP- and SOM-like neurons existed in the rostral, intermediate and caudal regions of the SCN and these neurons were overlapped and SOM-like neurons were scattered among them in the area between VIP- and AVP-like neurons. These findings may provide new morphologic evidences for explaining the functional mechanism in the SCN.