Effects of acute central and peripheral ACTH1–24 administration on lordosis behavior

The role of adrenocorticotropic hormone (ACTH) in the control of the lordosis reflex of female rats was investigated. Experiment 1 examined the effects of ACTH1–24 infused into the ventricular system of the brain. ACTH treatment lowered the performance of both ovariectomized (ovx) and adrenalectomized-ovariectomized (adx-ovx) extrogen-primed females. ACTH-treated females also showed evidence of spontaneous stretching, yawning, and grooming. Experiment 2 examined the effects of ACTH1–24 administered subcutaneously. Here ACTH elevated performance of ovx but not adx-ovx estrogen-primed females. There was no evidence of spontaneous stretching, yawning, and grooming movements in females given peripheral ACTH. In both experiments, untreated adx-ovx females showed a higher level of lordosis than untreated ovx females. These results suggest that the central effect of acute ACTH elevation differs from the peripheral effect, and that the peripheral effect is probably mediated by the adrenal.