Effects of nitric oxide donors sodium nitroprusside and 3-morpholino-sydnonimine on prolactin secretion in conscious rats

Abstract

In the present study, vie have examined the possible involvement of the central nitric oxide (NO) pathway in the control of prolactin secretion in vivo. The effects of intracerebroventricular (i.c.v.) injections of l-arginine ( l-Arg), a precursor of NO, N ω-nitro- L-arginine methyl ester ( l-NAME), an inhibitor of NO synthase (NOS), and of sodium nitroprusside (SNP) and 3-morpholino-sydnonimine (SIN-1), NO donors, on basal prolactin levels were studied in conscious male rats. Microinjections of l-Arg (100 and 500 μg) or l-NAME (100 and 500 μg) did not. modify plasma prolactin levels, however i.c.v. injections of both SNP (1, 5, 10 and 20 μg) and SIN-1 (1, 10 and 100 μg) induced dose-dependent increases in these levels although SNP was much more potent than SIN-1. These results suggest a role of NO in the control of prolactin secretion.