Appetitive operant behavior and free-feeding in rats exposed to acute stress

Bradley D. Youngblood, Donna H. Ryan, Ruth B.S. Harris

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


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-l0-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.

Original languageEnglish (US)
Pages (from-to)827-830
Number of pages4
JournalPhysiology and Behavior
Issue number4
StatePublished - Oct 1997
Externally publishedYes


  • Food intake
  • Food restriction
  • Free-feeding
  • Operant behavior
  • Rats
  • Restraint
  • Stress

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience


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