Time-dependent effects of amphetamine on feeding in rats.
Following administration of a moderate dose of amphetamine, rats appear to pass through a sequence of physiological/psychological states, including stimulant and depressant states. The present research evaluated whether these states could be inferred from time-dependent changes in feeding-related measures. Male rats were housed in individual stations (light-dark 12-12 h, free access to water) where, at 3-h intervals, they could respond for food for 1 h. The work requirement was fixed ratio 1, and each lever press produced six 94-mg food pellets. When the pattern of responding for food stabilized across the light-dark cycle, a series of 6 or 7 tests was run. During each test, rats received a saline treatment (1.0 ml/kg, subcutaneously) followed by a 48-h monitoring period, and then they received an amphetamine treatment (2.0 mg/kg, subcutaneously) followed by a 72-h monitoring period. Different groups were treated at either light onset or light offset. Lever presses and head-in-feeding-bin responses were monitored throughout these tests. Administration of amphetamine at light onset and at light offset produced cumulative food intake functions having four regions: post-treatment hours 1-6 (hypophagia), 7-12 (normal intake), 13-27 (hypophagia), and 28 and beyond (normal intake). The sequence, duration, and quality of the amphetamine-induced changes in food intake resembled those formerly seen in cue state and activity, and provided further evidence of a transient withdrawal state 20-24 h post-amphetamine treatment.
White
Wesley
W
Psychology Department, 601 Ginger Hall, Morehead State University, Morehead, KY 40351, USA. w.white@moreheadstate.edu
Sherrill
Luke K
LK
White
Ilsun M
IM
D000661:Amphetamine / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects*; D008297:Male; D051381:Rats; D012055:Reinforcement Schedule; D013997:Time Factors
D000697:Central Nervous System Stimulants; D000661:Amphetamine