[Expression of estrogen receptor beta in the hypothalamic paraventricular nucleus of postnatal female mice].

Previous studies have revealed that estrogen receptor beta (ER-beta) in the mouse hypothalamic paraventricular nucleus (PVN) may play different roles from that in the PVN of rat and other animal species. In the present study, the expression of ER-beta in the developing PVN of postnatal female mice was studied using nickel ammonium sulfate intensified immunocytochemical techniques, and the results showed that ER-beta immunopositive materials were predominantly localized in the magnocellular division of the PVN, only sparse positive cells were found in the parvocellular division and dorsal cap of the PVN. Most of the positive cells were strongly labeled, but some lightly labeled cells were also detected. No apparent positive signals were observed in the cytoplasm or the processes of the neurons. The highest levels of expression were found at early postnatal days (postnatal day 1 to 9), and then it decreased to lower levels from day 15 and thereafter. The above results together with other findings suggest that at early postnatal development, ER-beta may play important role in the regulation of the structure and function of PVN, such as neuroendocrine, morphological maturation, food intake and body weight increase of postnatal animals.