Affordable Access

Publisher Website

Interaction of thyroid hormone and sex steroids at the rabbit reticulocyte membranein vitro:Control by 17β-estradiol and testosterone of thyroid hormone-responsive Ca2+-ATPase activity

Archives of Biochemistry and Biophysics
Publication Date
DOI: 10.1016/0003-9861(84)90256-x
  • Hormone Structure And Function
  • Biology


Abstract Physiological concentrations (10 −10 m) of l-thyroxine and triiodo- l-thyronine were found in vitro to enhance Ca 2+-ATPase activity in reticulocyte-enriched red cell membranes from female rabbits and to inhibit this enzyme in the male reticuloycte. Cross-incubation experiments with reticulocyte-enriched red cells and plasma from the opposite sex demonstrated that this sex-specific membrane response to thyroid hormone was transferable by plasma. Similar experiments with intact reticulocytes exposed to physiological concentrations (10 −11 m) of testosterone and 17β-estradiol indicated that the plasma factors were the sex steroids. That is, incubation in vitro with testosterone converted female-source reticulocytes to male-type responsiveness to thyroid hormone (inhibition of Ca 2+-ATPase activity); incubation with estradiol converted male-source reticulocyte-enriched red cells to female-type responsiveness (stimulation by iodothyronines of membrane Ca 2+-ATPase activity). Similar results were obtained when reticulocyte ghosts were incubated with testosterone and 17β-estradiol prior to determination of membrane enzyme activity. Etiocholanolone (5β-androstan-3α-ol-17-one) and testosterone were equipotent, but 5α-dihydrotestosterone had little activity in this system. Estrone and estradiol were equipotent, but estriol had no permissive effect on the stimulation by iodothyronine of reticulocyte membrane Ca 2+-ATPase activity. Expression of thyroid hormone action in vitro on Ca 2+-ATPase activity in the rabbit reticulocyte is determined at the membrane level by testosterone and estrogen. The structure-activity relationships of the sex steroids for this membrane action are different than those reported for nuclear actions of the steroids.

There are no comments yet on this publication. Be the first to share your thoughts.