THE EFFECT OF INTERLEUKIN-2 ON THE RELEASE OF GONADOTROPIN AND PROLACTIN IN-VIVO AND IN-VITRO

To evaluate a possible physiological role of Interleukin-2 (IL-2) in t he control of Luteinizing hormone (LH), Follicle stimulating hormone ( FSH) and Prolactin (PRL) release, conscious, ovariectomized (OVX) rats were given injections of IL-2 into the third ventricle. The third ven tricular injection of IL-2 induced a significant decrease in plasma LH levels when compared to values in control animals (P<0.05). Plasma LH concentrations were significantly decreased within 5 min after the in jection of IL-2 and remained decreased for 1 h. In contrast, injection s of IL-2 had no effect on plasma FSH or PRL levels. To evaluate a pos sible direct action of IL-2 on LH, FSH and PRL release from the anteri or pituitary gland, the cytokine was incubated with dispersed anterior pituitary cells for 4 h. IL-2 in the dose range between 10(-1) and 10 (-3) unit stimulated the release of LH and FSH into the culture medium (P<0.05, P<0.025 vs, control, respectively). The release of PRL from incubated anterior pituitary cells was not affected at any dose of IL- 2 tested. These results indicate that IL-2 possibly plays an inhibitor y role in the control of gonadotropin secretion, via hypothalamic acti on, although it acts directly to stimulate the release of the gonadotr opins at the level of the anterior pituitary gland.