AJP - Endocrinology and Metabolism, Vol 254, Issue 5 E549-E554, Copyright © 1988 by American Physiological Society
Protein turnover in gravid and nongravid horns of uterus in pregnant rats
D. F. Goldspink and A. J. Douglas
Department of Physiology, Queen's University of Belfast, United Kingdom.
Changes in uterine protein, RNA, and DNA contents in gravid and nongravid
horns from the same animal were studied after 14 and 16 days of pregnancy.
At 16 days, all of these parameters of growth had increased between three-
and sevenfold in the gravid horn while remaining unchanged in the nongravid
horn compared with the uterus of nonpregnant control animals. In the
nongravid horn, the hormonal changes associated with pregnancy induced
antagonistic decreases in both the average rates of protein synthesis and
protein breakdown, with the net result being no change in its growth. In
the gravid horn, however, the hormonal influences are coupled with the
stretching effects produced by the enlarging fetuses. Here the net effect
was a marked suppression of protein breakdown, resulting in a fourfold
increase in its rate of growth. These data, together with those derived
from analysis of both fetal and nonfetal sites from the gravid horn, led to
the following conclusions. Changes in circulating hormones during pregnancy
do not alone appear to influence the overall size of the uterus. In
contrast, mechanical distension of the uterus promotes rapid and extensive
growth.
