[Distribution of nitric oxide synthase-positive neurons in the hypothalamus of cat]

NADPH-diaphorase histochemistry was used to study the distribution of Nitric Oxide Synthase (NOS)-Positive neurons in the hypothalamus of adult cat. NOS-positive neurons were observed in the paraventricular hypothalamic nucleus, suprachiasmatic nucleus, dorsomedial hypothalamic nucleus, perifornical nucleus, anterior hypothalamic area and lateral hypothalamic area. Two differences between the cat and rat were noticed. Firstly, NOS-positive neurons were observed in the suprachiasmatic nucleus of cat, but the neurons in that of rat were negative for NOS. Secondly, the neurons in supraoptic nucleus of rat exhibited an intensive reaction to NADPH-diaphorase, but those in that of cat were faintly visible.