Luteal macrophage conditioned medium affects steroidogenesis in porcine granulosa cells

The purpose of the study was to examine the effect of luteal macrophage conditioned medium (LMCM) on progesterone and estradiol production by cultured granulosa cells. Porcine granulosa cells were cultured for 48 h with or without LMCM in the absence or presence of 100 ng/ml LH, FSH or prolactin. Progesterone and estradiol concentrations were measured by radioimmunoassay. Granulosa cells were analyzed histochemically and immunocytochemically for the activity and presence of Δ5, 3β-hydroxysteroid dehydrogenase (3β-HSD), respectively. LMCM stimulated basal and LH-, FSH- or prolactin-induced progesterone secretion. Similarly, LMCM augmented basal and stimulated activity of 3β-HSD in the examined cells. In contrast, LMCM decreased LH- and prolactin-induced estradiol secretion but increased FSH-induced estradiol secretion. These data demonstrate the clear stimulatory effect of LMCM on granulosal progesterone production. It is concluded that substances secreted by macrophages modulate gonadotropin effect on follicular progesterone secretion in a paracrine manner via 3β-HSD activity.