Silva Ivaldo, Mello Luiz E A M, Freymüller Edna, Haidar Mauro A, Baracat Edmund C
Department of Gynecology, Universidade Federal de São Paulo, Brazil.
Menopause. 2003 Sep-Oct;10(5):406-11. doi: 10.1097/01.GME.0000064816.74043.E9.
The aim of this study was to evaluate differences between estrogen replacement therapy initiated either 4 or 12 days after ovariectomy on the synaptic density of the hippocampal CA1 field in rats.
Female, adult, Wistar rats were ovariectomized bilaterally under ether anesthesia and divided among the following groups: 1) estrogen (conjugated equine estrogen 50 microg in 0.5 mL of propylene glycol, daily, p.o. gavage, for 60 days), starting 4 days after ovariectomy (n = 5); 2) propylene glycol (0.5 mL daily, p.o. gavage, for 60 days), starting 4 days after ovariectomy (n = 4); 3) estrogen (conjugated equine estrogen 50 microg in 0.5 mL of propylene glycol, daily, p.o. gavage, for 45 days), starting 12 days after ovariectomy (n = 3); 4) propylene glycol (0.5 mL daily, p.o. gavage, for 45 days), starting 12 days after ovariectomy (n = 3). At the end of the treatment, the rats were processed for electron microscopy and light analysis.
Synaptic density in all of the CA1 strata subjected to evaluation was significantly higher in animals in which estrogen replacement was initiated 4 days after ovariectomy as compared with controls. In contrast, initiation of treatment after a 12-day interval did not result in recovery of synaptic density in any of the CA1 strata and was significantly lower than that of the animals subjected to hormone replacement after a 4-day delay (P < 0.01).
The delay for hormone replacement therapy might have critical implications for modulating synaptic density.
本研究旨在评估卵巢切除术后4天或12天开始进行雌激素替代疗法对大鼠海马CA1区突触密度的影响差异。
成年雌性Wistar大鼠在乙醚麻醉下双侧卵巢切除，并分为以下几组：1）雌激素组（结合马雌激素50微克溶于0.5毫升丙二醇中，每日经口灌胃，共60天），于卵巢切除术后4天开始给药（n = 5）；2）丙二醇组（0.5毫升每日经口灌胃，共60天），于卵巢切除术后4天开始给药（n = 4）；3）雌激素组（结合马雌激素50微克溶于0.5毫升丙二醇中，每日经口灌胃，共45天），于卵巢切除术后12天开始给药（n = 3）；4）丙二醇组（0.5毫升每日经口灌胃，共45天），于卵巢切除术后12天开始给药（n = 3）。治疗结束后，对大鼠进行电子显微镜检查和光镜分析。
与对照组相比，卵巢切除术后4天开始进行雌激素替代治疗的动物，所有接受评估的CA1层的突触密度均显著更高。相比之下，间隔12天开始治疗并未使任何CA1层的突触密度恢复，且显著低于延迟4天进行激素替代治疗的动物（P < 0.01）。
激素替代治疗的延迟可能对调节突触密度具有关键影响。
