Exercise training-induced changes in the anterior pituitary
gonadotrope of the female rat.
Caston, Anne L., Peter A. Farrell, and Daniel R. Deaver.
Noll Physiological Research Center and Departments of Exercise and
Sport Science and Dairy and Animal Science, The Pennsylvania State
University, University Park, Pennsylvania 16802
APStracts 2:0142A, 1995.
Chronic exercise training may alter the hypothalamic-pituitary-ovarian
axis by affecting gonadotropin secretion and structural indices of
the anterior pituitary gonadotropes. Young female Harlan Sprague
-Dawley rats were randomly assigned to either a 12-wk intensive
treadmill running program (n = 16) or to a sedentary, untrained group
(Untrained-proestrus, UTP, n = 16). After training for 3 months,
animals were sacrificed on proestrous morning and individual
pituitary glands were enzymatically dispersed into single cell
suspensions. Trained rats maintained either predominantly regular
estrous cycles (Trained-proestrus, TP, n = 11) or exhibited anestrous
vaginal cytology (Trained-anestrous, TA, n = 5). At sacrifice, plasma
estradiol concentrations for TP (57.4 + 6 pg/ml, mean + SE) and UTP
(54.6 + 5) were similar. However, TA had plasma estradiol levels (2.7
+ 0.2, p<0.05) reflecting their anestrous status. Basal LH
secretion ( 20-hr static incubation) was significantly reduced in
gonadotropes from TA (7.8 + 1.1 ng/pooled wells) compared to TP (13.6
+ 1.6) and UTP (12.6 + 1.0). Immunofluorescence LH staining and
cytoplasmic granularity were significantly lower within TA
gonadotrope population compared to that of TP and UTP rats. Evidence
of impaired basal LH secretion, reduced gonadotrope LH-specific
fluorescein content and reduced gonadotrope cytoplasmic granularity
in TA rats suggests, that concomitant with proposed changes in the
central neural drive, there are important exercise training-induced
alterations of the anterior pituitary gonadotrope that influence
their estrous cycles and affect their reproductive status.
Received 30 November 1994; accepted in final form 14 March 1995.
APS Manuscript Number A1220-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 April 1995.