Rat brain natriuretic peptide (BNP) reduces water intake following dehydration.

The effect of rat brain natriuretic peptide (BNP) on drinking behaviour was examined in dehydrated and well-hydrated rats. Following dehydration for 18h, intracerebroventricular injections of 5 micrograms of rat BNP significantly reduced water consumption 0-2 h after the injections, but not 2-4 h afterwards. Rat BNP failed to decrease water intake in animals given water ad libitum. Thus, rat BNP is similar to alpha-atrial natriuretic polypeptide in that it only affects drinking in dehydrated rats. Following dehydration, plasma vasopressin levels were decreased by BNP, but BNP did not affect serum osmolality and electrolyte metabolism. These findings suggest that BNP may be involved in the central regulation of water consumption.