COEXISTENCE OF PACAP AND NITRIC-OXIDE SYNTHASE IN THE RAT HYPOTHALAMUS

THE possible co-existence of pituitary adenylate cyclase-activating po lypeptide (PACAP)-38 and nitric oxide synthase (NOS) in the rat hypoth alamus was examined by a combination of PACAP-immunocytochemistry and NADPH-diaphorase histochemistry. Virtually all PACAP-38-immunoreactive neurones in the paraventricular and supraoptic nuclei exhibited NADPH -diaphorase activity. Since NADPH-diaphorase activity was identical to NOS-immunoreactivity in the magnocellular neurosecretory neurones, th is finding indicates that the PACAP neurones synthesize NO.