Effect of exertion on the stimulation of ornithine decarboxylase activity by growth hormone in rats.
To investigate the effect of stressful stimulation on tissue responsiveness to growth hormone (GH), we examined ODC activity as a measure of hepatic sensitivity to the hormone during forced exertion in rats. GH caused a 15-fold increase in ODC activity in the livers of resting rats at 3 hours after the injection of hormone. Forced walking in a rotating cylinder enhanced the effect of GH on ODC activity by up to 66% above the effect in resting rats, and this enhancement was positively related to the speed of rotation of the cylinder. These results suggest that tissue hypersensitivity to GH stimulation is a consequence of forced exertion. This hypersensitivity to GH would tend to compensate for the inhibitory effects of forced exertion on GH secretion in rats.
Martin
J V
JV
Department of Psychiatry, State University of New York, Stony Brook 11794-8101.
Wyatt
R J
RJ
Mendelson
W B
WB
D000818:Animals; D013006:Growth Hormone / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains
D013006:Growth Hormone; D009955:Ornithine Decarboxylase