Abstract (EN):
Estrogen actions on neurons of the principal division of the bed nucleus of the stria terminalis (BNSTpr) are essential for the regulation of female sexual behavior. However, little is known about the effects of estradiol and progesterone (P) on estrogen receptor alpha (ER alpha) expression in this nucleus. To study this subject, we used stereological methods to estimate the total number of ER alpha-immunoreactive (ER alpha-ir) neurons in the BNSTpr of female rats at each stage of the estrous cycle and of ovariectomized rats after administration of estradiol benzoate (EB) and/or P. To ascertain the percentage of ER alpha-positive neurons in the BNSTpr, the total number of neurons in this nucleus was also estimated. In order to identify the specific role played by the selective activation of each ER in the expression of ER alpha, ovariectomized rats were injected with the ER alpha agonist, propyl-pyrazole triol (PPT), or the ER beta agonist, diaryl-propionitrile (DPN). Data show that ER alpha is expressed in 40-60% of the BNSTpr neurons and that the number of ER alpha-ir neurons is lowest at proestrus. This value is paralleled by the administration of EB. The number of ER alpha-ir neurons was not modified by P. PPT induced no changes in the number of ER alpha-ir neurons. Contrariwise, DPN induced a decrease in the total number of ER alpha-ir neurons to values similar to those of EB-treated rats. These results show that P has no effect in the modulation of ER alpha expression and demonstrate that estradiol regulation of ER alpha in BNSTpr neurons is mediated by activation of ER beta.
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
8