Efeitos não-genômicos do estradiol na excitabilidade neuronal do Locus Coeruleus e núcleo mesencefálico trigeminal de ratos neonatos.

Abstract

The estradiol (17- estradiol) is a hormone recognized for its genomic or classical effects. Beyond that, it is well-established that such effect takes place over hours to days. However, a growing body of evidence has been accumulated on the rapid response of estrogen in the central nervous system. Moreover, the hormone response on electrophysiological properties of the developing nervous system remains poorly explored. Therefore, in the present study, we investigated the effects of estradiol on slices containing the locus coeruleus and mesencephalic trigeminal nucleus in newborn rats. The results provide evidences for a nongenomic response acting in both nuclei. Infact, the inhibitory effect evoked in the locus coeruleus was verified by thehyperpolarization and decreased cellular excitability levels. These findings expand the present status of knowledge of estradiol effects in the cell membrane of the nervous system of regions related to reproductive functions. In addition, the mesencephalic trigeminal nucleus neurons also showed suppression in its activity accompanied by ahyperpolarization of the membrane potential. The action of estrogen on the passive response in these neurons points out a possible interaction between estrogen and HCN channels (Hyperpolarization-activated cyclic nucleotide-gated). The results of this investigation contribute to the understanding of the modulatory estradiol effects in those areas not related to the reproductive functions. The proprioceptive nature of themesencephalic trigeminal nucleus provides a possible scenario for the estradiol impact in the early stages of the proprioception.