Somatostatin in physiological concentrations inhibits basal and enhances luteinizing hormone-stimulated progesterone release from human granulosa-luteal cells.

To study the effect of somatostatin on ovarian function, we investigated the action of physiological concentrations of somatostatin (5.0 x 10(-12)-1.0 x 10(-10) M) on the basal and luteinizing hormone (LH)-stimulated progesterone release from cultured human granulosa-luteal cells obtained from in-vitro fertilization patients. Somatostatin exerted a significant and inhibitory effect on basal progesterone release from the granulosa-luteal cells, whereas it was unable to inhibit LH-stimulated progesterone release. Instead, a significant increase in progesterone release was observed after concomitant incubation with LH and somatostatin compared with the untreated controls. We suggest that somatostatin may serve as a regulator of ovarian functions under physiological conditions.