Induction and subcellular redistribution of progesterone receptor A and B by tamoxifen in the hypothalamic ventromedial neurons of young adult female Wistar rats.
The ventrolateral division of the hypothalamic ventromedial nucleus (VMNvl) is a brain center for estrogen-dependent triggering of female sexual behavior upon progesterone receptor (PR) activation. We examined the agonistic and antagonistic actions of tamoxifen in this nucleus by analyzing its effects on the total number of PR-immunoreactive neurons, PR mRNA and protein levels, and subcellular location of PRs in ovariectomized Wistar rats. The results show that tamoxifen has no agonistic action in the number of PR-immunoreactive neurons, but increases PR expression and labeling in the nucleus and cytoplasm of VMNvl neurons that constitutively express PRs. As an antagonist, tamoxifen partially inhibited the estradiol-dependent increase in the number of PR-immunoreactive neurons and in PR mRNA and protein levels, without interfering with the subcellular location of the protein. We suggest that tamoxifen influence on PR expression in the VMNvl critically depends on the presence or absence of estradiol.
['Sá|Susana I|SI|', 'Fonseca|Bruno M|BM|', 'Teixeira|Natércia|N|', 'Madeira|M Dulce|MD|']
D000818:Animals D001835:Body Weight D002452:Cell Count D004958:Estradiol D005260:Female D009474:Neurons D011374:Progesterone D012333:RNA, Messenger D017208:Rats, Wistar D060888:Real-Time Polymerase Chain Reaction D011980:Receptors, Progesterone D013347:Subcellular Fractions D013629:Tamoxifen D014599:Uterus D014697:Ventromedial Hypothalamic Nucleus
Progesterone receptor Tamoxifen Hypothalamic ventromedial nucleus Estrogen receptor Stereology Western blot