Different physiological traits underlying increased body fat of
fatty (fa/fa) and heterozygous (+/fa) rats.
Schwarzer, Knut, Heiko D[diaeresis]oring, and Ingrid Schmidt.
W. G. Kerckhoff-Institut, Max-Planck-Institut f[umlaut]ur
physiologische und klinische Forschung, Parkstr. 1, D-61231 Bad
Nauheim, FRG
APStracts 3:0172E, 1996.
To find out whether the most characteristic physiological traits
distinguishing suckling-age fa/fa pups from lean littermates also
differ between +/+ and +/fa littermates, we analyzed the body
composition and cold defense of 7- and 16-day-old pups and the plasma
concentrations of insulin, glucose, triglycerides, and free-fatty
-acids in 16-day-old pups. Zucker rat X Brown Norway hybrid pups were
genotyped by using a molecular marker within 0.5 cM of the fa gene.
At both ages the +/fa pups had significantly more body fat than their
+/+ littermates. At 7 days this difference was as large as that
between +/fa and fa/fa pups, but at 16 days it was only one seventh
of the fa/fa vs. +/fa difference. In contrast, there were no
heterozygote differences for three parameters that show crucial
abnormalities in the fa/fa pups: thermoregulatory thermogenesis and
plasma concentrations of insulin and triglycerides. The physiological
mechanisms underlying the increased fat content of +/fa pups thus
differ not only quantitatively but qualitatively from those fueling
that of their fa/fa littermates.
Received 20 March 1996; accepted in final form 12 August 1996.
APS Manuscript Number E142-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996