AJP - Regulatory, Integrative and Comparative Physiology, Vol 260, Issue 3 546-R552, Copyright © 1991 by American Physiological Society
Food deprivation-induced vs. drug-induced feeding: a behavioral evaluation
A. S. Levine, M. A. Kuskowski, M. Grace and C. J. Billington
Department of Medicine, VA Medical Center, Minneapolis 55417.
Several neuroactive substances including neuropeptide Y (NPY), muscimol,
and norepinephrine (NE) stimulate feeding in satiated rats. In the present
study, we observed the behavioral patterns of rats stimulated to eat by
food deprivation or by intracerebroventricular (icv) injection of
orexigenic agents to explore the hypothesis that such agents produce a
behavioral state resembling hunger. Animals that were food deprived for 24
h spent the majority of their time eating (35%), drinking (5%), resting
(44%), and moving (13%) when food was available. If food was removed and
substituted with a chewable substrate (plastic tube), they chewed on tubes
for a brief period (5%) but spent most of their time moving (14%) or
resting (77%). In the absence of food or tubes, they briefly moved about
the cage (4%) and spent almost all of their time resting (94%). The
patterns observed with the orexigenic drugs were different, particularly in
the absence of food. NPY-injected rats were more active than deprived rats,
spending 22% of their time moving in the presence of food, 47% in the
presence of tubes, and 37% in the absence of food or tubes. Rats injected
with muscimol demonstrated a marked increase in the time spent chewing and
eating. These rats spent 67% of their time eating in the presence of food
and chewed 25% of the time in the absence of either food or tubes.
NE-injected rats also chewed when tubes were present (17%) or when no food
or tubes were present (10%). Lag sequential analysis further documented
differences in behavioral patterns amongst the various treatments.(ABSTRACT
TRUNCATED AT 250 WORDS)
