Gonadectomy in the spring reinstates hibernation in male golden
-mantled ground squirrels.
Dark, John, Dawn R. Miller, and Irving Zucker.
Departments of Psychology and Integrative Biology, University of
California, Berkeley, CA 94720, USA
APStracts 3:0005R, 1996.
We tested the hypothesis that continued secretion of gonadal steroids
is necessary to suppress hibernation in male golden-mantled ground
squirrels in the weeks after the terminal arousal in spring. Juvenile
and adult males were gonadectomized or sham-gonadectomized one week
after the terminal arousal; 64% of castrated and none of the sham
-procedure animals resumed hibernation. Latency to resumption of
torpor was 9 +/- 2 days from the time of castration and squirrels
underwent 4.3 +/- 0.9 bouts before permanently regaining euthermia.
Among squirrels that resumed hibernation, bout duration was
significantly shorter and torpor was shallower after castration.
Castration as late as 3 weeks after the terminal arousal reinstated
hibernation. We suggest that the terminal arousal of male squirrels
in the spring is provoked by a steroid-independent mechanism similar
to that operating earlier in the hibernation season; abandonment of
hibernation is contingent on concomitant sustained increases in
androgen secretion during the first few weeks of euthermia.
Received 28 August 1995; accepted in final form 18 December 1995.
APS Manuscript Number R534-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96