Co-existence of PACAP and nitric oxide synthase in the rat hypothalamus.

The possible co-existence of pituitary adenylate cyclase-activating polypeptide (PACAP)-38 and nitric oxide synthase (NOS) in the rat hypothalamus 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, this finding indicates that the PACAP neurones synthesize NO.