Gonadal and photoperiodic influences on body mass regulation in
adult male and female prairie voles (microtus ochrogaster).
Kriegsfeld, Lance J., and Randy J. Nelson.
Department of Psychology, Behavioral Neuroendocrinology Group, and
Department of Population Dynamics, Reproductive Biology Division, The
Johns Hopkins University, Baltimore, MD 21218-2686 USA
APStracts 2:0331R, 1995.
Nontropical animals commonly use the annual change in photoperiod to
phase seasonal adjustments that promote survival and reproduction. In
order to cope with the energetic requirements of winter, many rodents
alter body mass in anticipation of winter. Photoperiodic adjustments
are often mediated by the pineal hormone, melatonin; melatonin can
exert a primary effect on body mass or a secondary effect on body
mass by changing blood gonadal steroid levels which may influence
body mass. The present study sought to determine if prairie voles
(Microtus ochrogaster) alter body mass in response to short
photoperiods. The role of the gonads in body mass regulation was also
assessed. In Experiment 1, males housed in short days increased body
mass at a greater rate than long-day animals. Gonadectomy enhanced
the body mass gain in short-day voles. These data suggest that the
gonads contribute to short photoperiod-induced changes in body mass
in male voles. In Experiment 2, females housed in short days
increased body mass at a greater rate than long-day animals,
regardless of whether or not the animals were ovariectomized.
Ovariectomy did not affect body mass in either long- or short-day
animals, suggesting that the ovaries do not contribute to
photoperiod-mediated changes in body mass in female prairie voles.
Taken together, these studies suggest that male and female prairie
voles use photoperiodic information to time seasonal changes in body
mass.
Received 28 June 1995; accepted in final form 13 November 1995.
APS Manuscript Number R403-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95