AJP - Regulatory, Integrative and Comparative Physiology, Vol 242, Issue 3 285-R295, Copyright © 1982 by American Physiological Society
Water regulation in weanling hypodipsic dorsomedial hypothalamic-lesioned rats
L. L. Bellinger and L. L. Bernardis
Weanling rats with dorsomedial hypothalamic nuclei lesions (DMN-L) are
hypodipsic and hypophagic when compared to sham-operated rats. When tested
for interdependence of food and water intake (WI) the DMN-L rats drank in
the absence of food and ate in the absence of water. The data suggest DMN-L
rats are not prandial drinkers. On testing for intracellular thirst (5.8 or
5.4% NaCl, 1 ml/100 g body wt), extracellular thirst [polyethylene glycol
(PG), 25% wt/vol, 0.5 ml/35 g body wt], or a combination of both thirsts,
the DMN-L rats responded as well or better than the control animals when
the test data were expressed as a percentage of the rat's base-line WI.
Both groups were more responsive to PG when tested in the light phase. When
injected with angiotensin II (200 micrograms/100 g body wt) both groups
responded similarly. Therefore, whereas the DMN-L rats were hypodipsic in
comparison to controls, they respond as well or better than control animals
when classical thirst testing procedures are utilized. It is suggested that
DMN-L may have "reset" WI similarly to the previously proposed reset for
body weight and food intake.
