RESUMO
The effect of duration of handling for vaginal smear screening on the adrenal weight and acute ACTH response to ether were examined in 4-day-cycling female rats, sacrificed at 97-103 days of age on diestrus-2 after evaluation of resistance to handling, thymus weight, and hypothalamic serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA). Prolonged handling paralleled increased resistance (behavioral response) to handling and adrenal weight but was inversely related to thymus weight. The hypothalamic 5-HT, 5-HIAA, and 5-HIAA/5-HT ratio, compared to controls with similar conditions of handling, were not modified after 2.5 min of ether despite the ACTH rise. In ether-stressed rats, the ACTH response to ether was lower after prolonged handling compared to short handling paralleling decreased thymus weight. In contrast, 5-HT, 5-HIAA, and the 5-HIAA/5-HT ratio were higher, paralleling increased resistance and adrenal weight. The results suggest chronic activation of the hypothalamo-pituitary-adrenal axis with positive serotonergic involvement after prolonged handling and resistance during vaginal screening and a negative implication of this activation on the acute ACTH response to ether.