Gao Y, He J R, Kapcala L P
Department of Medicine, University of Maryland School of Medicine, Baltimore 21201, USA.
Brain Res Mol Brain Res. 1997 May;45(2):340-4. doi: 10.1016/s0169-328x(97)00028-4.
Many in vitro studies show estrogen regulation of the hypothalamic pro-opiomelanocortin (POMC) system, including a decrease in hypothalamic POMC mRNA after estradiol treatment. Because such in vivo experiments do not allow one to determine whether peripheral, interacting systems or extra-hypothalamic brain regions are involved in this regulation, we sought to establish whether estrogen acts directly in hypothalamus to decrease POMC mRNA. Using an in vitro approach, we studied effects of estradiol (E2) on POMC/cyclophilin mRNA concentrations (RNAse protection assays) in neuronal cultures derived from day 17 fetal rat hypothalamus. Chemically defined medium was deprived of progesterone for 2 days prior to E2 treatment and for the duration of the study. E2 (10(-13)-10(-9) M) dose-dependently decreased POMC mRNA concentrations during a 2-day treatment. Whereas the lowest dose (10(-13) M) of E2 resulted in a statistically significant 44% decrease in POMC mRNA concentrations relative to control cultures, this inhibitory effect was lost because higher doses (10(-11) and 10(-9) M) did not produce statistically significant decrements (22 and 16%, respectively) in POMC mRNA concentrations. Additional time course studies revealed that this decrease in POMC mRNA can be seen as early as 4 h after E2 (10(-13) M) treatment. We conclude that E2 inhibition of POMC mRNA concentrations in hypothalamic neuronal cultures indicates that this inhibition can occur directly in hypothalamus.
许多体外研究表明雌激素对下丘脑阿片-促黑素细胞皮质素原（POMC）系统具有调节作用，包括雌二醇处理后下丘脑POMC mRNA水平降低。由于此类体内实验无法确定外周相互作用系统或下丘脑外脑区是否参与这种调节，我们试图确定雌激素是否直接作用于下丘脑以降低POMC mRNA水平。我们采用体外方法，研究了雌二醇（E2）对源自17日龄胎鼠下丘脑的神经元培养物中POMC/亲环蛋白mRNA浓度的影响（核糖核酸酶保护测定）。在E2处理前2天及整个研究期间，化学限定培养基中不含孕酮。在为期2天的处理过程中，E2（10^(-13)-10^(-9) M）呈剂量依赖性降低POMC mRNA浓度。相对于对照培养物，最低剂量（10^(-13) M）的E2使POMC mRNA浓度在统计学上显著降低了44%，但由于较高剂量（10^(-11)和10^(-9) M）未使POMC mRNA浓度产生统计学上的显著降低（分别为22%和16%），这种抑制作用消失。额外的时间进程研究表明，在E2（10^(-13) M）处理后4小时即可观察到POMC mRNA的这种降低。我们得出结论，E2对下丘脑神经元培养物中POMC mRNA浓度的抑制表明这种抑制可直接在下丘脑发生。
