The precise mechanism by which estrogen hormones influence brain feminization is not fully
understood. According to some data, this process occurs during the prepubertal period. In our
study, we divided female subjects into five groups. Four of them had their ovaries removed on
the 10th day after birth, and from the 15th to the 25th day of age, we administered substances
dissolved in corn oil that activate various estrogen hormone signaling pathways: 1) estradiol
benzoate, 2) agonist of estrogen receptor α (ERα) propyl pyrazole triol, 3) agonist of estrogen
receptor β - diarylpropiontril, 4) corn oil (negative control). For the fifth group (positive
control), we used females that also received corn oil, but whose ovaries were removed after
puberty (at 60 days of age). We evaluated feminization by observing female sexual behavior
(lordosis), expression of tyrosine hydroxylase in the anteroventral part of the periventricular
nucleus of the hypothalamus, and expression of ERα in the ventromedial nucleus of the
hypothalamus. We found no statistically significant differences in lordosis or expression of
these proteins in the brains of the different groups. Lordosis was weakly expressed in all groups,
especially in the positive control. Our results suggest that activation of estrogen hormone
signaling pathways had no lasting effects on the parameters we studied, and thus did not affect
feminization. However, it is very likely that other factors influenced the results that may have
disrupted the normal course of active feminization, particularly with respect to lordosis.
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