Low expression and absence of biological effect of the beta3
-adrenoceptor in guinea pig brown and white adipocytes.
Atgi[acute]e, Claude, Genevi[grave]eve Tavernier, Fran[cedilla]cois
D'allaire, Tore Bengtsson, Luc Marti, Christian
Carp[acute]en[acute]e, Max Lafontan, Ludwik Jan Bukowiecki, and
Dominique Langin.
Laval University, Medical School, Department of Physiology,
Qu[acute]ebec, P. Q., Canada, G1K 7P4; Institut National de la
Sant[acute]e et de la Recherche M[acute]edicale, Unit[acute]e 317,
Institut Louis Bugnard, Facult[acute]e de M[acute]edecine,
Universit[acute]e Paul Sabatier, 31054 Toulouse Cedex, France and the
Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm
University, S-106 91 Stockholm, Sweden
APStracts 3:0220R, 1996.
Cold-acclimation induced, in the guinea pig, a conversion of
unilocular to multilocular adipocytes in interscapular (IS) and
retroperitoneal (RP) fat depots but not in the epididymal (EP) fat
pad. The conversion was associated with an increase in
mitochondriogenesis and the appeareance of the uncoupling protein.
The maximal lipolytic responses to norepinephrine and dibutyryl cAMP
were decreased in IS-cells, not changed in RP-cells and increased in
EP-cells suggesting a site-specific regulation of lipolysis at the
post-receptor level. [beta]3-Adrenergic agonists were not lipolytic
regardless of the depot and the thermal environment of the animal.
These agents did not inhibit glucose transport and lipogenesis, as
was previously reported for rodents. Cloning and sequencing of the
guinea pig [beta]3-adrenoceptor gene revealed a slightly higher amino
acid sequence similarity with the human than with the rodent [beta]3
-adrenoceptors. [beta]3-adrenoceptor transcripts were present at a
very low level in guinea pig adipocytes and mRNA levels did not
increase to a significant extent after cold acclimation. The guinea
pig thus differs from rodents by an absence of [beta]3-adrenergic
effects and by low [beta]3-adrenoceptor expression in brown and white
adipose tissues.
Received 29 November 1995; accepted in final form 24 May 1996.
APS Manuscript Number R752-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96