Ansonoff M A, Etgen A M
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Endocrinology. 1998 Jul;139(7):3050-6. doi: 10.1210/endo.139.7.6088.
Estrogen acts in the brain to regulate female reproductive physiology and behavior, and protein kinase C (PKC) is estrogen-regulated in many estrogen-responsive tissues. We examined whether estrogen regulates PKC in the hypothalamus (HYP) and preoptic area (POA), brain regions which mediate estrogenic control of female reproductive function. PKC activity in tissue from hormone-treated and control female rats was measured, in the presence of phorbol ester and calcium, by quantifying 32p incorporation into a substrate peptide. PKC catalytic activity increased significantly in POA tissue extracts from estradiol-treated, ovariectomized (OVX) female rats but not in HYP or cortical extracts. Phorbol ester potentiation of cAMP accumulation also was examined to determine whether the ability of PKC to potentiate adenylyl cyclase activity was affected by estrogen. PKC stimulation potentiated forskolin-induced cAMP accumulation to a greater degree in POA, but not HYP, slices from estrogen-treated OVX female rats. PKC enzyme levels were examined using phorbol-12,13-dibutyrate binding assays and immunoblots. Estrogen treatment did not change phorbol ester binding affinity or the density of binding sites in the POA or HYP. Immunoblots for the alpha, beta, and gamma PKC isoforms combined, or the gamma PKC isoform alone, did not detect differences between hormone-treated and control OVX female rats. Therefore, estrogen treatment increased PKC catalytic activity in the POA of OVX female rats but not in the HYP. However, the increased PKC catalytic activity was not correlated with detectable changes in the level of the alpha, beta, or gamma PKC isoforms or in the density of phorbol ester binding sites.
雌激素作用于大脑以调节雌性生殖生理和行为，并且蛋白激酶C（PKC）在许多雌激素反应性组织中受雌激素调节。我们研究了雌激素是否调节下丘脑（HYP）和视前区（POA）中的PKC，这两个脑区介导雌激素对雌性生殖功能的控制。通过量化32P掺入底物肽的量，在佛波酯和钙存在的情况下，测量激素处理和对照雌性大鼠组织中的PKC活性。在经雌二醇处理的去卵巢（OVX）雌性大鼠的POA组织提取物中，PKC催化活性显著增加，但在HYP或皮质提取物中未增加。还检查了佛波酯对cAMP积累的增强作用，以确定PKC增强腺苷酸环化酶活性的能力是否受雌激素影响。在经雌激素处理的OVX雌性大鼠的POA切片中，而非HYP切片中，PKC刺激对福斯可林诱导的cAMP积累的增强程度更大。使用佛波醇-12,13-二丁酸酯结合测定和免疫印迹检查PKC酶水平。雌激素处理未改变POA或HYP中佛波酯的结合亲和力或结合位点密度。对α、β和γ PKC同工型组合或单独的γ PKC同工型进行的免疫印迹未检测到激素处理和对照OVX雌性大鼠之间的差异。因此，雌激素处理增加了OVX雌性大鼠POA中的PKC催化活性，但在HYP中未增加。然而，PKC催化活性的增加与α、β或γ PKC同工型水平或佛波酯结合位点密度的可检测变化无关。
