Journal of Applied Physiology, Vol 43, Issue 5 839-843, Copyright © 1977 by American Physiological Society
Adrenocortical function in aging exercise-trained rats
J. A. Severson, R. D. Fell, J. G. Tuig and D. R. Griffith
Plasma corticosterone concentrations and in vitro adrenal secretion of
corticosterone were determined in exercise-trained rats. Rats, 100, 200,
and 300 days of age, were trained for a 10-wk period by treadmill running.
Following the training program, rats were subjected to an acute bout of
swimming. Acute swimming elevated plasma corticosterone concentrations in
all age groups. At 170 days of age, the plasma corticosterone concentration
following swimming was higher in exercise-trained rats than in controls.
The opposite was true of acutely swum rats at 270 and 370 days of age.
Acute swimming elevated the in vitro adrenal gland response to
adrenocorticotropic hormone stimulation in control rats at all ages and in
trained rats at 170 days of age. The in vivo relationship of epinephrine
and the pituitary adrenal system is suggested as a mechanism which could
have caused this response. The relationship of secretion rates to plasma
corticosterone concentrations indicated that extra-adrenal mechanisms, such
as decreased turnover, were also responsible for the elevated plasma
corticosterone levels observed in response to acute swimming.
