Short day-like body weight changes do not prevent fat pad
compensation after lipectomy in siberian hamsters.
Mauer, Mary Margaret, and Timothy J. Bartness.
Department of Biology and Psychology, Neurobiology Program and
Neuropsychology and Behavioral Neuroscience Program, Georgia State
University, Atlanta, GA 30303
APStracts 3:0293R, 1996.
Long day (LD)-housed Siberian hamsters show compensatory increases in
white adipose tissue (WAT) weight after lipectomy, whereas hamsters
exposed to short days (SDs) for a long duration (22wks) do not. We
tested whether SD-induced body weight changes prevent fat pad
compensation after lipectomy. In Exp.1, hamsters with lesions of the
paraventricular nucleus of the hypothalamus (PVNx) rapidly increased
body weight similar to 22wk SD-exposed hamsters. In Exp.2, LD-housed
hamsters were food-restricted for 22wks and then pair-fed to SD
-housed hamsters for 12wks, to produce body weight changes mimicking
those of ad libitum-fed SD-exposed animals. Epididymal WAT lipectomy
(EWATx) of PVNx or food-restricted hamsters elicited compensatory
increases in retroperitoneal and inguinal WAT (RWAT and IWAT)
weights. Unlike other fat pads, EWAT was less affected by food
restriction or PVNx than by SD exposure. Food restriction decreased
adipocyte number, whereas SD exposure decreased adipocyte size. PVNx
increased RWAT adipocyte size and IWAT adipocyte number. These
results suggest that the lack of body fat compensation by EWATx
hamsters exposed to SDs for a long duration is due to SD-associated
responses other than body weight changes per se.
Received 22 March 1996; accepted in final form 2 July 1996.
APS Manuscript Number R175-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996