Dissociation between behavioral and hormonal responses to the forced swim stress in lactating rats.

摘要: Retention of immobility in the Porsolt forced swim test is believed to be dependent upon glucocorticoid secretion male rats. Because lactating females exhibit increased basal and blunted stress responses, we tested hypothesis that lactation-induced changes adrenal circulating estrogen progesterone levels would improve retention and/or acquisition immobility. Immobility was recorded during 3 intervals 5 min on day 1 (acquisition) one interval 24 h later (retention). Blood samples were collected before at various times after onset for plasma ACTH corticosterone (B) determinations. Male rats (young = 200 g, old 325 g) compared virgin (V) early (day 8-10, EL) late 17–19, LL) lactation. Adrenalectomy (ADX) ovariectomy (OVX) performed 10 days prior testing, respectively. All animals acquired end 15 1, but only young group exhibited a significant 2. Total higher males than although stress-induced B comparable both testing days. Lactational status did not affect either or phases. However, greatly diminished intact ADX (EL virgins (LL < EL virgin), demonstrating clear dissociation between behavioral neuroendocrine responses. Following ADX, phase decreased females. Finally, OVX (EL) without significantly altering magnitude responses stress. In summary, our results demonstrated sex-related lactation-related differences endocrine Porsolt. Although immobile response thought involve glucocorticoids opioids secreted first session, find evidence direct relationship total secretion, scores period. experimental variables such as body weight, sex water depth could modify outcome question validity glucocorticoid-mediated processes. Since effect reversed rats, hypothesize sensitivity cognitive processes controlling reactivity different from hypothalamic-adrenocortical function. Our also test, particular In lactation, responsiveness caused by enhanced feedback might result modifications inhibitiory stimulatory inputs hypothalamic neurons adrenocortical activity.