Effect of Gonadal Steroids on the Luteinizing Hormone and Follicle-Stimulating Hormone Response to 8-Bromo-Adenosine 3′,5′-Monophosphate in Anterior Pituitary Cells in Culture

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Abstract
8-Bromo-c[cyclic]AMP stimulated the release of LH [luteinizing hormone] (.apprx. 20-fold) and FSH (.apprx. 2-fold) in control rat anterior pituitary cells in primary culture. 8-Bromo-cAMP-induced LH release was 2-3 times greater in cells preincubated for 48 h in the presence of 10-8 M 17.beta.-estradiol (E2). The LH response to 10-10 M LHRH [luteinizing hormone releasing hormone] was similarly increased by E2 pretreatment whereas progesterone (P), which had no effect on the response to 8-bromo-cAMP, led to a reduction of the stimulatory effect of E2 on the LH response to the neurohormone. Preincubation with 10-8 M testosterone (T) decreased the LH response to 8-bromo-cAMP by about 40%, whereas the response to LHRH was 80% inhibited. 8-Bromo-cAMP induced FSH release was slightly increased in cells preincubated with E2 but was greatly augmented in cells treated with E2 + P. Basal FSH release was slightly increased (40%) after preincubation with P or T whereas the response to 8-bromo-cAMP was not significantly affected. The sensitivity of the FSH response to LHRH was increased by E2 whereas P and T led to a stimulation of the maximal FSH response to LHRH with no significant effect on the LHRH ED50 [median effective dose] value. P and E2 exert their effects on LH and FSH release at steps before and after cAMP formation, respectively. T appears to act at both steps on the release of the 2 gonadotropins.