Estrogen receptor-dependent regulation of sensory neuron survival in developing dorsal root ganglion

Estrogen is known to influence different functions in brain tissue ranging from neuronal development to plasticity and survival, but the mechanisms in volved have not been defined clearly. Previous studies have shown the prese nce of the two estrogen receptors (ERs), ER alpha and ER beta, in several b rain areas, but less is known about the role of estrogen in the peripheral nervous system. Here we demonstrate that dorsal root ganglion (DRG) neurons express ER alpha and ER beta during early postnatal development and in cul ture, and that the ERs localize mainly to neuronal cell nuclei. Studying th e role of estrogen in DRG, we observed that low concentrations of 17 beta-e stradiol increased survival of cultured DRG neurons deprived of nerve growt h factor. 17 beta-Estradiol up-regulated the expression of the antiapoptoti c molecule Bcl-x without affecting that of Bar, suggesting a mechanism by w hich the hormone counteracted neuronal death. Antiestrogens abolished the a ction of 17 beta-estradiol in the DRG neurons, which demonstrates an involv ement of ERs. The results show that estrogen and ERs play an important role in the development and survival of DRG neurons.