AJP - Regulatory, Integrative and Comparative Physiology, Vol 240, Issue 1 81-R86, Copyright © 1981 by American Physiological Society
Lack of ingestive compensation to osmotic stimuli in chronic decerebrate rats
H. J. Grill and R. R. Miselis
Chronic decerebrate rats fitted with oral fistulas for remote injection of
water or nutrient were tested for their capacity to behaviorally compensate
for dehydration by increasing their ingestion of water. Decerebrates and
their controls were given water for ingestion via the oral fistula in
50-microliter aliquots following various challenges. The rats' ejection of
water from the mouth marked behavioral termination of the drinking. The
volume of water was measured 1 and 24 h after an intragastric meal of
regular diet; 0.5, 4, 8, and 24 h following subcutaneous isotonic or
hypertonic NaCl injection; and 1, 4, 8, and 24 h following an intragastric
meal of regular or 3% NaCl adulterated diet. Unlike controls, decerebrates
failed to increase the amount of water ingested following intracellular
dehydration regardless of the means of producing dehydration or the
duration of time permitted for a response. However, both control and
decerebrate rats increased their ingestion of a sweet solution (0.03 M
sucrose) demonstrating their capacity to respond and confirming their
ability to compensate for food deprivation. This lack of increased water
intake in response to dehydration for decerebrate rats favors the existence
of at least some aspects of the regulatory circuitry for this behavioral
control of water balance to lie in the forebrain.
