Exposure to juvenile stress exacerbates the behavioural consequences of exposure to stress in the adult rat.
To examine the effects of exposure to post-weaning pre-puberty (juvenile) stress on the emotional and cognitive abilities in response to exposure to stress in adulthood, we first exposed rats to a platform stress at the age of 28 d. Two months later the rats were exposed to acute swim stress. Rats exposed to both stressors showed a higher level of anxiety (as measured both in open-field and startle response tests) than controls or rats exposed to either the juvenile or the adulthood stressor. In the Morris water-maze, rats that were exposed to both juvenile and adulthood stress performed better than the other groups. In a second experiment we verified that the effect of the juvenile stress was indeed age-dependent. One group was exposed at the age of 26-28 d and again at the age of 60 d (juvenile + adulthood stress); the other group was exposed to the first stressor at the age of 60-62 d and to the second at the age of 90 d [adulthood (60) + adulthood (90) stress]. Juvenile + adulthood stress had a significantly greater effect than exposure to stress twice in adulthood, on anxiety level and on the performance in the water-maze. Finally, in a third experiment we found that the juvenile+adulthood stress group swam faster and tended to explore the central area more than the other groups--a finding that could explain their better performance on the first trial of the spatial task. These results indicate that an exposure to a relatively brief juvenile stressful experience has profound and long-lasting effects on the ability to cope with stress in adulthood.
Avital
Avi
A
Department of Psychology and The Brain & Behavior Research Center, University of Haifa, Mount Carmel, Haifa, Israel.
Richter-Levin
Gal
G
D000375:Aging / Q000523:psychology*; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D005106:Exploratory Behavior / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000502:physiology; D012741:Sexual Maturation / Q000502:physiology*; D013037:Spatial Behavior / Q000502:physiology*; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming