Time course of peptidergic expression in fetal suprachiasmatic nucleus transplanted into adult hamster.

The time course of peptidergic expression in fetal suprachiasmatic nucleus (SCN) grafted into the third ventricle of adult hamsters was compared to SCN in situ in age-matched animals. Specifically, vasoactive intestinal polypeptide- (VIP), vasopressin- (VP) and neuropeptide Y- (NPY) like immunoreactivity in SCN was examined after transplantation into adult hosts on embryonic day 15 (E15) and in age-matched control SCN tissue. The results indicate that the grafted SCN expresses VIP by day 7-10, VP by day 10-16, and NPY by day 19-25 after transplantation. The SCN in situ expresses VIP by E14, VP by postnatal day 1 (P1), and NPY by P7. The transplantation procedure seems to produce a developmental regression or delay of a few days in detectable peptidergic expression in the SCN. The developmental delay seen in tissue implanted into the third ventricle is substantially less than that previously reported in SCN tissue implanted into the anterior chamber of the eye. The delay in peptidergic expression in transplanted SCN tissue may account, in part, for the delay in restoration of circadian locomotor rhythmicity following transplantation of SCN into lesioned adult hosts.