丙酸睾酮预处理对HIBD新生鼠脑细胞神经生长因子表达的影响

Study on protective effect and its mechanism of pretreatment of testosterone propionate on hypoxic-ischemic brain damage in the neonatal rats

【目的】观察丙酸睾酮预处理对新生鼠缺氧缺血性脑损伤(hypoxic-ischemic brain damage,HIBD)大脑皮质和海马区神经生长因子(nerve growth factor,NGF)的表达及神经细胞凋亡的影响,并探讨其保护作用机制。【方法】新生3日龄SD大鼠随机分为3组:正常对照组(n=24),HIBD组(n=24),T预处理组(n=24)。T预处理组大鼠于3日龄时给予T预处理。HIBD组和T预处理组大鼠于7日龄时进行HIBD模型制作。于HI后12、24、72h、7d观察各组脑组织病理形态及应用Nissl染色法测定神经元数目而间接检测神经细胞坏死和凋亡。并于HI后24、72h、7d制作石蜡切片,用免疫组化SABC法观察NGF在各组大鼠大脑皮质和海马表达的动态变化。【结果】HI后24、72h和7d,正常对照组和HIBD组大鼠脑皮质和海马区仅见极少量阳性细胞表达,而T预处理组大鼠于HI后24h和72h NGF表达水平明显增高(P<0.05)。正常对照组和HIBD组大鼠海马区偶尔可见NGF免疫阳性细胞表达,T预处理组大鼠海马区于HI后72h出现NGF免疫阳性细胞表达轻微增多,与正常对照组和HIBD组比较差异均有显著性(P<0.01)。【结论】丙酸睾酮预处理可明显见减轻大脑皮质神经细胞凋亡、增加HIBD新生大鼠脑皮质和海马区NGF表达,从而发挥神经保护作用。

[Objective] To observe the effects of testosterone propionate pretreatment on nerve growth factor（NGF） expression and neural necrosis and apoptosis so as to explore the possible mechanism. [ Methods] 3-day-old Sprague- Dawley （SD） rats were randomly divided into three groups： control group （n= 24）, HIBD group （n= 24） ,pretreatment with testosterone propionate group （n= 24）. Pretreatment with testosterone propionate group was pretreated at 3 day old. Making HIBD model on 7-day old SD rats of HIBD and pretreatment with testosterone propionate groups. [Results] Observing changes of brain nerve cells of ischemic side （left side） hemisphere in HIBD group showed significant damages including indistinct cell structure, derangement of array, nerve cell degeneration, necrosis, cell collapse, massive apoptotic cells, reactive hyperplasia of glial cells; nerve cells of ischemic side （left side） hemisphere in pretreatment with testosterone propionate group showed less severe damages than HIBD group, seldom seeing apoptosis. Adopting Nissl staining analy- zing by image acquiring and analysis system of computer, the density of cortical and hippocampal neurons in HIBD group decreased obviously compared with control group（P〈0.05）, while degree of neuron loss in pretreatment with testosterone propionate group was relieved than HIBD group（P〈0.05）. Viewing a small quantity of NGF positive cells in cortex and hippocampus of control and HIBD groups at 24.72 h and 7 d after HI, while the expression of AR positive cells in pretreatment with testosterone propionate group increased apparently at 24 h and 72 h after HI （P〈0.05）. [Conclusions] Testosterone propionate pretreatment could apparently up-regulate NGF expression on cortex and hippocampus in neonatal rats after HIBD to reduce, levels of cellular necrosis and apoptosis on cortex and hippocampus alleviated to compare with purely HIBD group after HI. Suggesting that pretreatment of extrinsic and rogen could decrease impairment in HIBD.