HIGH-LEVELS OF SPECIFIC NEUROPEPTIDE Y PANCREATIC POLYPEPTIDE RECEPTORS IN THE RAT HYPOTHALAMUS AND BRAIN-STEM/

It is known that the paraventricular hypothalamic nucleus is responsib le for some of the stimulatory effects of neuropeptide Y, peptide YY a nd the pancreatic polypeptides on food intake. However, specific neuro peptide Y Y-1 and Y-2 receptors were not abundantly expressed in the h ypothalamus. In contrast, specific [I-125]human pancreatic polypeptide binding sites were detected in this hypothalamic nucleus as well as i n the medial preoptic area, interpeduncular nucleus, nucleus tractus s olitarius, area postrema and dorsal vagal nucleus while cortical areas and the hippocampus contained negligible levels of labeling. The liga nd binding profile of the various competitors suggests that the bindin g sites labeled by [I-125]human pancreatic polypeptide are predominant ly of the neuropeptide Y Y-4 and/or Y-5 subtypes. These newly cloned r eceptors may play a key role in the modulatory effects of neuropeptide Y and related peptides on appetite.