STRESS AND THE ADRENOCORTICAL RESPONSE: ENRICHED PAST EXPERIENCE REDUCES THE STRESS RESPONSE.
HUMAN ENGINEERING LABS ABERDEEN PROVING GROUND MD
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First-litter male Wistar rats were either handled or not handled on Days 1-15 following birth. In adulthood they were exposed for three minutes to a large open field for one, two, three or four days. Fifteen minutes after the last exposure they were sacrificed and free plasma corticosterone was assayed. Handled subjects showed a significantly lower adrenocortical response to the open field than non-handled subjects. This finding supports the previously reported open-field findings from these same subjects Hudgens, 1970 which showed that early handled subjects react less emotionally when exposed to a novel environment. The mothers were re-bred twice to rear second and third litters which were not handled in infancy. These litters received four days of open-field testing before being sacrificed. No differences were obtained on the corticosterone measure as a function of the mothers first litters being handled or non-handled. Some methodological difficulties are discussed. Author
- Anatomy and Physiology