Treadmill exercise training and estradiol increase plasma acth and prolactin after novel footshock. White-Welkley, Jill E., Gordon L. Warren, Bradford N. Bunnell, Edward H. Mougey, James L. Meyerhoff, and Rod K. Dishman. Departments of Exercise Science and Psychology, The University of Georgia, Athens, Georgia, Department of Medical Neurosciences, Walter Reed Army Institute of Research, Washington, D.C.
APStracts 2:0555A, 1995.
We examined whether rats that were treadmill exercise trained (TR) or chronically immobilized (CI) had similar responses by the hypothalamic-pituitary-adrenal (HPA) cortical axis to acute stress and whether the HPA responses interacted with the hypothalamic -pituitary-gonadal (HPG) axis. Following 6 wk (1 h/d, 6 d/wk) of TR or CI, plasma [adrenocorticotropin] (ACTH), [prolactin], and [corticosterone] were measured after familiar (treadmill running or immobilization) or novel (footshock) stress. Ovariectomized Sprague -Dawley females (N=72) were implanted with capsules containing estradiol benzoate (E2) and randomly assigned in a 2-group (E2 vs No E2) x 3-treatment (TR vs CI vs sedentary) x 4-acute stressor (footshock vs treadmill running (RUN) vs immobilization (IM) vs no stress) x 3-recovery time (min 1 vs 15 vs 30) mixed model ANOVA. E2 capsules were removed from half the animals 48 h prior to the first stressor session. After 10-min of acute stress, blood was drawn from a jugular catheter at min 1, 15, and 30 of recovery. [ACTH] and [prolactin] after footshock were higher in TR rats with E2 compared with CI and sedentary rats without E2; recovery levels for sedentary animals were higher after RUN compared with IM. The elevation in [corticosterone] from min 1 to 15 of recovery was higher after the familiar RUN and IM conditions. Our findings are consistent with an increased responsiveness of the HPA axis to novel footshock after treadmill exercise training that is additionally modulated by the HPG axis. 

Received 8 July 1994; accepted in final form 18 October 1995.
APS Manuscript Number A682-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95