外源性雌激素对去势后大鼠下丘脑视上核一氧化氮合酶阳性神经元分布的影响

目的观察外源性雌激素对去势后雌性大鼠下丘脑视上核(SON)一氧化氮合酶(NOS)阳性神经元分布的影响。方法选用2～3月龄、健康未交配的雌性大鼠40只;动物分组如下:对照组大鼠20只,分为正常对照组(n=10)和实验对照组(卵巢切除术后,n=10)。实验组(即卵巢切除术后肌肉注射雌激素组)20只,造模成功后,分别于术后40d(即给药一个月)和术后70d(即给药两个月)陆续灌注取材。采用SABC法在光学显微镜下对下丘脑视上核内NOS阳性神经元进行形态学观察和细胞计数,采用图像分析系统测定NOS阳性神经元内免疫反应产物的平均灰度值。结果卵巢切除术后对照组大鼠下丘脑视上核NOS阳性神经元的密度明显增高,细胞比正常对照组有所增大(P0.05)。去势后补充雌激素1个月组的大鼠与正常对照组和卵巢切除组相比较,视上核内NOS阳性神经元的密度及形态均无明显改变(P0.05)。去势后补充雌激素两个月组与实验对照组相比较,无论NOS阳性神经元的密度还是阳性神经元胞体的大小均显著下降(P0.05),细胞着色变浅。结论外源性雌激素可能影响去势雌性大鼠下丘脑视上核NOS阳性神经元的分布和表达。

Effects of exogenous estrogen on the distribution of nitric oxide synthase positive neurons in supraoptic nuclus of hypothalamus of ovariectomized female rats

Objective To observe how exogenous estrogen influences the distribution and the expression of NOS positive neurons in the supraoptic nuclei of hypothalamus in the overiectomized female rats. Methods The 2-3-month-old female rats(n=40) were selected as the healthy and nulli-copulatory experimental animals. Rats were divided into following groups: normal control group(n=10), ovariectomized control group(n=10), and two experimental groups that have been injected with estrogen for post-operative 40 days(n=10) and for post-operative 70 days(n=10). Finally, all the animals were infused and the brains were removed. Immunohistochemical (SABC) method was adopted to count the number of NOS poitive neurons and observed the NOS poitive neuronal morphology under the light microscope. The image analysis system was used to test the average gray value of immunoreactivity in NOS positive neurons. Results In the ovariectomized control group, the density of NOS positive neurons in supraoptic nucleus was significantly increased and their shapes were bigger than that of the normal control group(P<0.05). The density and the form of the NOS positive neurons in supraoptic nucleons had no apparent difference between the estrogen for post-operative 40 days group and the ovariectomizeed control group(P>0.05).In the group after estrogen-injection 2 months compared with the normal control group, and the ovariectomized control group, both of the NOS positive neurons' density and the size become significantly decreased, and the staining of cells was lesser in the group injected with estrogen for post-operation 70 days. Conclusion The present results suggest that exogenous estrogen may influence the distribution and the expression of NOS positive neurons in supraoptic nucleus of hypothalamus of ovariectomized female rats.