Objective: To study the effect of leptin on the expression of calcium-activated neutral protease 1 (calpain-1) and B cell lymphoma-2 (Bcl-2) and apoptosis in the myocardial tissue of neonatal rats after asphyxia.
Methods: A total of 48 neonatal rats were randomly and equally divided into normal control group, asphyxia group, leptin treatment groups, and calpain-1 inhibitor (CAI-1) group. The neonatal rat model of asphyxia under normal atmospheric condition was established in all groups except the control group. For the leptin treatment groups, rats received 20, 80, and 160 μg/kg leptin by intraperitoneal injection immediately after model establishment, respectively. For the CAI-1 group, rats received 10 mg/kg CAI-1 by intraperitoneal injection immediately after model establishment. For all the groups, the myocardial tissue was collected at 2 hours after model establishment. Immunohistochemistry was used to measure the expression of calpain-1 and Bcl-2. The TUNEL method was used to evaluate apoptosis of myocardial cells.
Results: The expression of calpain-1 and Bcl-2 and apoptosis index (AI) were significantly higher in the asphyxia group than in the normal control group (P˂0.05). The leptin treatment groups and the CAI-1 group had significantly lower expression of calpain-1, significantly lower AI, and significantly higher expression of Bcl-2 than the asphyxia group (P˂0.05). The CAI-1 group had the largest changes in all the indices compared with the asphyxia group. However, there were no significant differences in all indices between the 160 μg/kg leptin treatment group and the CAI-1 group. After asphyxia, the expression of calpain-1 was positively correlated with AI, while the expression of Bcl-2 was negatively correlated with AI and the expression of calpain-1 (P˂0.05).
Conclusions: Leptin reduces apoptosis of myocardial cells in asphyxiated neonatal rats by the inhibition of calpain-1 activation and upregulation of Bcl-2 expression.
目的: 研究瘦素对窒息新生大鼠心肌组织钙依赖中性蛋白酶（calpain-1）、B淋巴细胞瘤-2（Bcl-2）的表达及心肌细胞凋亡的影响。
方法: 将48只新生大鼠随机分为正常对照组、窒息组、瘦素处理组（L20组、L80组、L160组）和calpain-1抑制剂组（CAI-1组）。建立新生大鼠常压窒息模型，各瘦素处理组在造模后立即给予瘦素20、80、160 μg/kg进行腹腔注射，CAI-1组造模后立即给予calpain-1抑制剂10 mg/kg腹腔注射。各组均在造模完成后2 h取心肌组织，免疫组化法检测calpain-1、Bcl-2的表达，Tunel法检测心肌细胞凋亡指数（AI）。
结果: 窒息组calpain-1、Bcl-2的表达及AI值较正常对照组均明显升高（P < 0.05）；各瘦素处理组、CAI-1组calpain-1表达水平及AI值较窒息组显著下降，Bcl-2表达水平较窒息组显著升高（P < 0.05）；与窒息组相比，各指标变化均以CAI-1组最显著，且与L160组比较差异均无统计学意义（P > 0.05）；窒息后各组calpain-1与AI值呈正相关，Bcl-2与calpain-1和AI值均呈负相关（P < 0.05）。
结论: 瘦素可抑制calpain-1的活化，上调Bcl-2表达，从而减少窒息新生大鼠心肌细胞凋亡。