EFFECT OF A GNRH ANALOG ON RAT GRANULOSA-CELL LACTATE PRODUCTION INVITRO

The effect of a GnRH [gonadotropin-releasing hormone] analog ((D-Ala6,des-Gly10-NH2)-GnRH-ethylamide (GnRHa)) on granulosa and cumulus cell glycolysis in the presence or absence of FSH was studied. Cumulus complexes and granulosa cells from PMSG[pregnant mare serum gonadotropin]-treated rats were cultured in Eagle''s minimal essential medium (MEM) for a period of 72 h. Media were changed at 24 and 48 h, and lactate content was assayed by fluorimetry. GnRHa alone stimulated lactate production in granulosa cells. GnRH combined with FSH increased lactate production in granulosa cells during the 0-24 h period and decreased it during the 48-72 h period as compared to FSH alone. GnRHa did not stimulate lactate production in cumulus complexes during 72 h culture in MEM, while FSH did. In a less complex culture medium, BMOC, GnRHa caused a small increase in lactate production and slightly enhanced the FSH effect. GnRHa has a direct stimulatory effect on granulosa cell glycolysis. GnRHa also modulates the FSH stimulation of granulosa cells biphasically, i.e., early enhancement (0-24 h) and late inhibition (48-72 h). GnRHa has no consistent direct effects on cumulus cell glycolysis.