Appetitive operant behavior and free-feeding in rats exposed to acute stress.
This study investigated whether appetitive operant food reinforcement or free-feeding behavior in rats, food-restricted to 85% of body weight, was disrupted by exposures to 3 h of restraint stress or by 3 h of restraint plus water immersion stress (RWI). Rats were trained under a 3-cycle 10-min time-out-10-min time-in fixed-ratio 15 (FR15) schedule of food reinforcement. Free-feeding was measured in a 3-cycle 10-min food jar-out-10-min food jar-in test conducted in the operant chambers. Three hours of restraint stress did not significantly affect response rate or food reinforcement in the operant FR15 task or in the free-feeding condition. In contrast, 3 h of RWI completely abolished operant food reinforcement and suppressed response rate, whereas free-feeding was significantly reduced but not abolished in food-restricted, hungry rats. We conclude that acute restraint stress in food-restricted, hungry rats does not affect their appetite or motor ability to lever-press for food nor did it affect their ability to feed in a free-feeding situation. In contrast, RWI stress may have induced a motor impairment, or some other aspect of motivation independent of hunger, that disrupted their performance in the operant FR15 task.
Youngblood
B D
BD
Department of Neuroscience, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
Ryan
D H
DH
Harris
R B
RB
D000818:Animals; D001066:Appetite / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology*; D004195:Disease Models, Animal; D005247:Feeding Behavior / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000503:physiopathology*; D013997:Time Factors