AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 2 380-R386, Copyright © 1984 by American Physiological Society
Specific depletion of body fat in parabiotic partners of tube-fed obese rats
R. B. Harris and R. J. Martin
One member in each of 15 parabiosed pairs of rats was fed twice its normal
food intake as four tube-fed meals per day. Seven other pairs ate ad
libitum. Partners of overfed rats ate approximately 90% of the intake of
individual members of ad libitum pairs. After 46 days of overfeeding, blood
samples were taken and the rats were killed for carcass analysis. Tube-fed
parabiotic rats had gained a considerable amount of fat and some protein.
Their partners had a normal lean body mass but very little fat. Serum
corticosterone, reverse triiodothyronine, free fatty acids, and
beta-hydroxybutyrate were the same in all parabionts. Serum
triiodothyronine and insulin were increased and growth hormone was
decreased in obese rats. Serum thyroxine and triiodothyronine were
increased and glucose was decreased in their parabiotic partners. The
results are discussed as evidence for a humoral factor that crossed the
parabiotic union and acted as a "lipid-depleting" agent in the partners of
overfed rats.
