Prolactin-releasing peptide-immunoreactivity in A1 and A2 noradrenergic neurons of the rat medulla

Distribution of prolactin-releasing peptide-like immunoreactivity (PrRP-LI) was investigated in the rat medulla with the use of a rabbit polyclonal an tiserum against the human PrRP-31 peptide, PrRP-positive neurons were noted mainly in two areas of the caudal medulla: ventrolateral reticular formati on and commissural nucleus of the nucleus of the solitary tract (NTS), corr esponding to the Al and A2 areas. PrRP-LI neurons were absent in the medull a rostral to the area postrema. Double-labeling the sections with PrRP anti sera and tyrosine hydroxylase (TH) monoclonal antibodies revealed extensive colocalization of PrRP- and TH-like immunoreactivity (TH-LI) in neurons of the Al and A2 areas. Our results show that PrRP-LI is expressed in a popul ation of Ar and A2 noradrenergic neurons of the rat caudal medulla. (C) 199 9 Elsevier Science B.V. All rights reserved.