EFFECTS OF L-ARGININE ON ANGIOTENSIN II-RELATED WATER AND SALT INTAKES

Nitric oxide (NO) has been implicated centrally as an inhibitory neuro modulator, acting in short feedback loops. Neurons capable of NO synth esis have been localized in various thirst-related hypothalamic nuclei . Intracerebroventricular (icy) injection of L-arginine (L-arg), the p recursor for NO, has previously been shown to attenuate both dehydrati on-and angiotensin II (Ang II)-induced drinking behavior. The present study further examines the effects of L-arg on drinking. We confirmed that icy administration of L-arg (50 mu g) reduced water intakes induc ed by both 24 h water deprivation and icy Ang II (250 ng). We addition ally showed that L-arg inhibited the water intake induced by periphera l injection of Ang II and the intake of 0.3 M NaCl following 24 h sodi um depletion. We demonstrated the behavioral specificity of L-arg trea tment by showing that it did not inhibit the intake of sucrose in food deprived rats and did not act as an unconditional stimulus for the fo rmation of a conditioned taste aversion. These results lend further su pport to the idea that NO plays a role in modulating fluid balance and drinking behavior. (C) 1998 Elsevier Science Inc.