Fig. 2.
Hippocampal estradiol synthesis is regulated by GnRH. a Estradiol synthesis of dispersion cultures of hippocampal neurons was measured by RIA after treatment with GnRH for 8 days. Estradiol synthesis increased significantly after treatment with intermediate doses of 10−8 and 10−7 M GnRH, as compared to the control. No such increase was seen with the highest dose of 5 × 10−7 M (mean ± SEM; n = 5). b Treatment of hippocampal neurons with the aromatase inhibitor letrozole (10−7 M) inhibited GnRH-induced estradiol synthesis. Treatment of the neurons with 10−7 M letrozole alone resulted in a significant downregulation of estradiol synthesis, as demonstrated earlier. The increase in estradiol synthesis induces by 10−8 M GnRH was blocked by simultaneous treatment of the dispersion cultures with the GnRH antagonist antide (10−7 M) (mean ± SEM; n = 5, *P ≤ 0.05 compared with control)