AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 4 760-R767, Copyright © 1990 by American Physiological Society

ARTICLES

Testosterone influences hibernation in golden-mantled ground squirrels

T. M. Lee, K. Pelz, P. Licht and I. Zucker
Department of Psychology, University of California, Berkeley 94720.

At different phases of the hibernation season, castrated male golden-mantled ground squirrels were implanted with capsules that either were filled with testosterone (T) or left empty (blank). Blank-treated animals hibernated normally when housed at 5 degrees C. Entry into hibernation was prevented in the majority of squirrels treated with T several days before the initial cold challenge. T concentrations that inhibited torpor (greater than 1.2 ng/ml) were comparable with those of intact males at the end of the hibernation season. In some squirrels, moderate T concentrations were compatible with hibernation, but torpor bout duration was shorter than normal. The inhibitory effect of T on hibernation did not appear to require aromatization of T to estradiol. We suggest that a steroid-independent mechanism triggers arousal from hibernation and that T-dependent processes determine whether hibernation is resumed at the end of an arousal period.

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