Stimulation of glucose transport in cultured uterine cells by rat and rabbit uterine extracts

Abstract

Estradiol-17β was previously shown to stimulate glucose transport (as measured by phosphorylation of 2-deoxyglucose) in rat uterine tissue in vivo (Meier D.A. and Garner C.W. (1987) Endocrinology 121, 1366–1374) but attempts to demonstrate this in uterine organ strips in vitro, in uterine tumor cell lines or in uterine cells in primary culture have been unsuccessful. However, aqueous uterine extracts and uterine luminal fluid did stimulate glucose transport in uterine tumor cells and uterine cells in primary culture. Estradiol in vivo and uterine extracts in vitro each increased the initial rate of glucose transport 1.5- to 3-fold. In each case, 2–3 h were required for the stimulation to be fully expressed. The stimulation was not inhibited by cycloheximide suggesting that protein synthesis was not required. Uteri from ovariectomized rats injected daily for 4 days with 10 μg estradiol contained 4-fold more activity than uteri from saline-injected control animals. The activity was acid- and heat-stable, inactivated by trypsin treatment but not removed by dextran-coated charcoal treatment, suggesting that the activity is (or is associated with) a protein. The activity eluted in the 6–12 kDa range upon chromatography on Sephadex G-50. Insulin (1–1000 ng/ml) and epidermal growth factor (1–100 ng/ml) stimulated glucose transport, but only less than 50% of the stimulation by extracts. The substance(s) present in the extracts, possibly a known growth factor, may be involved in the estradiol stimulation of glucose transport and other estradiol actions in vivo.