Estradiol stimulates GDNF expression in developing hypothalamic neurons

Estrogens stimulate the differentiation of neurons and neural networks in the CNS. The concordance of the cellular responses of estrogens and growth factors suggests that both factors may interact on the cellular level to ensure their developmental role. We have put forward this hypothesis and analyzed the effect of estrogens on the expression of glial cell line-derived neutrotrophic factor (GDNF) in developing hypothalamic cells. Using Western blotting and competitive RTPCR, we have demonstrated that 17beta-estradiol (E2) increases the expression of GDNF in hypothalamic cell cultures. E2-induced GDNF expression was seen in neurons but not astrocytes. GDNF induction by E2 appeared to be transmitted through nonclassical estrogen action, since the application of the nuclear estrogen receptor antagonists ICI 182, 780 did not abolish this effect. Only inhibitors of intracellular Ca(2+) and cAMP/protein kinase A signaling were effective in preventing E2 effects. We conclude that E2 is capable of influencing GDNF expression in the developing hypothalamus. Thus, it is conceivable that developmental E2 effects in the hypothalamus are partially mediated through the regulation of other important developmental signals such as growth factors.