Acute Effects of Pituitary Gonadotrophins on the Metabolism of Isolated Rat Ovaries1

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Abstract
Since many experimental data indicate that enhanced amino acid uptake accompanies the hormonal stimulation of growth in certain target tissues, a study was made of the action of pituitary gonadotrophins (FSH and LH) on the transport of the nonutilizable amino acid, α-aminoisobutyric acid (AIB), into isolated rat ovaries. Ovarian glucose uptake and oxygen consumption were also measured. Whole ovaries from prepubertal and hypophysectomized rats were incubated for 2 hr in Krebs-Ringer phosphate buffer containing AIB-C14 and glucose. At the end of the incubation period, the amount of radioactivity in the cell water and glucose uptake from the medium were measured. It was found that injection of FSH in one intravenous dose 4 hr before removal of the ovaries consistently and significantly stimulated the accumulation of AIB-C14 by the isolated ovaries. Neither ovarian glucose uptake nor oxygen consumption was stimulated by the intravenous injection of FSH. Addition of FSH directly to the incubation medium did not stimulate AIB-C14 uptake. Intravenous injection of LH did not influence significantly the accumulation of AIB-C14, but this treatment exerted a pronounced stimulatory action upon glucose uptake by isolated ovaries. The stimulatory action of LH on glucose uptake was found also when this hormone was added directly to the incubation medium. The results are discussed particularly in relation to previous experimental data showing an effect of growth hormone on amino acid transport by the isolated rat diaphragm.