EXPRESSION OF PACAP, AND PACAP TYPE-1 (PAC(1)) RECEPTOR MESSENGER-RNADURING DEVELOPMENT OF THE MOUSE EMBRYO

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoact ive intestinal polypeptide (VIP) have been reported to have a number o f neurotrophic effects. We have examined the expression of mRNA for PA CAP and PACAP type 1 (PAC(1)) receptor in the mouse embryo by in situ hybridization and the effects of PACAP and VIP on the growth of mouse embryos in vitro. Although we were unable to detect gross effects of e ither peptide on the growth rates of embryos maintained in culture, mR NAs for both PAC(1) receptor and PACAP peptide were present in the ner vous system from day 9.5 of embryonic development. PAC(1) receptor mRN A was most abundant in the neural tube and the rhombencephalon and was present also in the dorsal root and trigeminal ganglia and the sympat hetic chain. The distribution of mRNA for the PACAP peptide overlapped in part with that of the receptor, but was more extensively distribut ed in the rhombencephalon and in the developing hypothalamus. Within t he neural tube, PAC(1) receptor mRNA was located in the roof and floor plates, while the distribution of PACAP peptide mRNA was more complex , being located in two columns of cells in the ventromedial neural tub e (consistent with the position of developing autonomic motor neurons) and in cells in the dorsolateral neural tube. These data are concorda nt with a role for PACAP or a related peptide in neural development. ( C) 1998 Elsevier Science B.V. All rights reserved.