Peripheral control of drinking: Gastrointestinal filling as a negative feedback signal, a theoretical and experimental analysis.

Abstract

Conducted 5 experiments to investigate the hypothesis that the osmotic postingestional satiety signal proposed by R. A. McCleary (1953) operates through a mechanism related to gut filling rather than by osmotically induced shifts of fluid from osmoreceptors in the brain. Ss were a total of 15 male albino Sprague-Dawley rats and 31 Charles River rats. A control theory model, designed to make quantitatively explicit the hypothesis under question, is presented. Results show that when mannitol, which is not absorbed from the intestine, is added to a highly palatable saccharin-glucose mixture, the amount of fluid consumed decreased in inverse proportion to the mannitol concentration. Mannitol blocked fluid absorption from the intestine at a low concentration and at higher concentrations to lead to a net flux of fluid into the intestinal lumen. It was also shown that mannitol in concentrations that reduced the intake of the palatable solution did not induce thirst when Ss were in water balance. It did induce thirst when Ss were tested in a state of negative water balance. Results, considered as a whole, support the view that McCleary's osmotic postingestional satiety signal acts as an intestinal distention signal rather than by inducing thirst. (48 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)