孕酮对大鼠脑损伤后神经细胞保护作用及其可能机制

Neuroprotective effect of progesterone on neurons after traumatic brain injury in rats and its mechanism

目的:探讨孕酮(PROG)对大鼠创伤性脑损伤(TBI)后神经细胞保护作用及其可能的机制.方法:雄性SD大鼠108只随机分为假手术组,损伤组和PROG治疗组,每组36只.按照改进的Feeney自由落体损伤装置制作大鼠脑损伤模型,建模后6,12,24,48,72和144h各组分别利用末端脱氧核酸转移酶介导的三磷酸鸟苷末端标记法(TUNEL)测定大鼠海马CA1区神经细胞凋亡,利用免疫组织化学方法测定大鼠海马CA1区Bcl-2,Bax的表达.结果:假手术组未见神经细胞凋亡,Bcl-2和Bax阳性细胞;PROG治疗组伤后24,48和72h神经细胞凋亡数分别为9.80±1.36,10.90±1.13,9.50±1.62,低于损伤组细胞凋亡数11.60±1.95,13.20±1.04,11.80±1.84,差异有统计学意义(P<0.05,P<0.01);PROG治疗组大鼠脑组织中Bcl-2阳性神经细胞表达高于损伤组(P<0.05,P<0.01),Bax阳性神经细胞表达低于损伤组(P<0.05,P<0.01);PROG治疗组损伤后12,24,48,72和144hBcl-2/Bax细胞比值分别为3.84±0.49,3.48±0.72,3.31±0.38,3.94±0.67,4.88±0.93,大于损伤组Bcl-2/Bax比值2.91±0.74,2.43±0.52,2.34±0.41,2.99±1.04,3.69±0.87,差异有统计学意义(P<0.05,P<0.01).结论:脑损伤后,PROG可能通过促进Bcl-2的表达,抑制Bax的表达,增加Bcl-2/Bax比值,从而减少神经细胞凋亡.

AIM： To investigate the neuroprotective effect of progesterone （PROG） on neurons after traumatic brain injury （TBI） in rats and the possible mechanism. METHODS- 108 Male Spraque-Dawley rats were randomly divided into 3 groups： sham-operated group （ n = 36）, PROG-treated group （ n = 36 ） and TBI group （ n = 36）. The rat models of TBI were duplicated with the improved Feeney＇s method. At 6, 12, 24, 48, 72 and 144 h after establishment of models, the nerve cell apoptosis in hippocampal CA1 was determined with TUNEL method, and the expression of Bcl-2 and Bax were detected with immunohistochemistry. RESULTS. No apoptotic cells, Bcl-2 and Bax positive nerve cells were detected in the sham-operated group. The number of apoptotic cells of the PROG-treated group were 9.80 ± 1.36, 10.90± 1.13, 9.50± 1.62 at 24, 48 and 72 h after injury respectively, less than those of the TBI group, which were 11.60 ±1.95, 13.20 ± 1.04, 11.80± 1.84 respectively. There were significant differences between the PROG-treated group and the TBI group in TUNEL positive ceils at 24, 48 and 72 h after injury （P 〈 0.05, P 〈 0. 01 ）. Bcl-2 positive nerve ceils in the PROG-treated group were more than those in the TBI group （ P 〈 0.05, P〈0.01 ）. Bax positive nerve ceils in the PROG-treated group were less than those in the TBI group （P 〈 0.05, P 〈 0.01 ）. The ratios of Bcl-2 to Bax positive nerve cells in the PROG-treated group were 3.84 ± 0.49, 3.48 ± 0.72, 3.31± 0.38, 3.94±0.67, 4.88±0.93 at 12, 24, 48, 72 and 144 h after injury respectively, higher than those in the TBI group, which were 2.91 ±0. 74, 2.43± 0. 52, 2. 34 ± 0. 41, 2. 99 ± 1.04, 3. 69 ± 0. 87 respectively. There were significant differences between the PROG-treated group and the TBI group at 12, 24, 48, 72 and 144 h after injury （P 〈0.05, P 〈0.01）. CONCLUSION： The administration of PROG may increase the expression of Bcl-2, suppress the expression of Bax, increase the ratio of Bcl-2 to Bax, and reduce nerve cell apoptosis. These results indicate that PROG exerts neuroprotective effects on the neurons after TBI.