MOLECULAR AND CELLULAR ANALYSIS OF RP1.B IN THE RAT HYPOTHALAMUS - IN-SITU HYBRIDIZATION AND IMMUNOHISTOCHEMISTRY OF A NEW P-DOMAIN NEUROPEPTIDE

P-domain peptides, a new family of secretory polypeptides, have been i dentified mainly in the gastroenteropancreatic tract of humans, rodent s, and amphibians as well as in amphibian skin. In the present study, with PCR and RNA analysis a transcript has been discovered in rat brai n termed rP1.B. The deduced polypeptide consists of a single P-domain and its amino acid sequence matches that of rat intestinal trefoil fac tor (rlTF). Thus far, rP1.B is the only P-domain peptide expressed in neuronal cells of the CNS. Immunostained magnocellular perikarya were visible in the paraventricular, supraoptic and periventricular nuclei. Parvocellular rP1.B neurons were found in the arcuate nucleus. Additi onally, specific hybridization signals with radiolabeled transcripts w ere observed in the same regions. rP1.B in the rat hypothalamus may be involved in the control of hypothalamo-hypophysial functions.