EFFETCS OF LH AND HCG ON THE METABOLISM OF THE PREPUBERTAL RAT OVARY: STIMULATION OF AMINO ACID TRANSPORT, PROTEIN SYNTHESIS, AND GLYCOLYSIS

Abstract

ABSTRACT It has earlier been reported from this laboratory that FSH can stimulate amino acid uptake, protein synthesis and glycolysis in the isolated prepubertal rat ovary. In the present investigation the effects of LH and HCG were studied. The hormones were injected to prepubertal female rats, and the ovaries were extirpated for incubation in Krebs bicarbonate buffer 120 min later. Injection of 1 μg/100 g body weight of a bovine LH preparation (NIH-LH-B8) produced a significant increase in the in vitro uptake of [14C]α-amino-isobutyric acid ([14C]AIB) and [3H]leucine as well as of the incorporation of radioactivity into the ovarian protein. Higher doses (10 and 100 μg) of NIH-LH-B8 gave only minor further increases. Lactic acid production during the incubation period was also measured as a determination of the rate of glycolysis. Lactic acid production was stimulated by the LH injections with a clear dose-response between 0.1 and 10 μg/100 g body weight. The effects of LH were also investigated with shorter intervals between the injection of the hormone and the extirpation of the ovaries. While lactic acid production was maximally stimulated at a time interval of 30 min (the shortest time interval studied), 60 min was necessary for the stimulation of amino acid uptake and amino acid incorporation into protein. Injections of HCG mimicked the effects of LH on all parameters studied.