Effect of stress and food variety on food intake in male and female rats.
Male and female rats were divided into two groups: stress (20 min of immobilization) and no stress. All animals were then given either one or three palatable foods for a 2 h test session. Each rat received both the single (one food) and variety (three foods) conditions twice, in a balanced order, in an ABAB experimental design. Stressed animals ate less than nonstressed animals. Animals ate more in the variety condition than in single condition during the first set of test sessions only. The stimulating effect of variety on food intake was not evident during the replication of conditions. All animals ate more of the palatable test foods than chow in a comparable time period. Rats ate more with each successive test session (regardless of food variety condition), showing a relative stabilization of food intake from the third to the fourth test sessions. However, there was a significant interaction of stress condition, sex, and test session. Stressed females continued to increase their food intake from the third to the fourth test session such that there was no longer any difference between the stressed and nonstressed females during the last test session. These results suggest that the effect of variety on food intake habituates when the same test foods are used repeatedly, and that there is no difference between males and females in the response to variety. Furthermore, while stress reduces the intake of palatable foods in all animals, females may show an habituation to this effect.
Zylan
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Department of Psychology, Lynchburg College, VA 24501, USA.
Brown
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SD
D000821:Animal Feed; D000818:Animals; D003345:Corticosterone / Q000097:blood; D004435:Eating / Q000502:physiology*; D005260:Female; D007103:Immobilization; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013315:Stress, Psychological / Q000523:psychology*
D003345:Corticosterone