脑源性神经营养因子对小鼠结肠平滑肌细胞的作用及其机制

目的 探讨脑源性神经营养因子(BDNF)对小鼠结肠平滑肌细胞(SMC)钙离子浓度及α-平滑肌激动蛋白(α-SMA)的影响及其相关调节机制。方法 Western blotting法检测BDNF基因敲除(BDNF^+/-)小鼠与正常野生型(BDNF^+/+)小鼠α-SMA表达水平的差异。培养原代小鼠结肠SMC,免疫荧光法检测SMC中酪氨酸激酶B(TrkB)受体的表达。同时以BDNF、TrkB受体阻滞剂(K252a)干预SMC,Western blotting法检测α-SMA和TrkB-PLC-Ca²⁺信号通路蛋白表达水平的变化,钙离子成像法检测SMC内钙离子浓度的变化。结果 与BDNF^+/+小鼠相比,BDNF^+/-小鼠结肠α-SMA表达水平明显降低。SMC表达TrkB受体,在BDNF作用下,SMC中α-SMA、TrkB-PLC-Ca²⁺信号通路蛋白表达量和细胞内钙离子浓度增加,且加入K252a可阻断以上变化。结论 BDNF可能通过TrkB-PLC-Ca²⁺信号通路作用于SMC,影响细胞内钙离子浓度及α-SMA的表达水平,进而影响肠道动力。

Effects of brain-derived neurotrophic factor on colon smooth muscle cells and the mechnism in mice

Objective To investigate the effects of brain-derived neurotrophic factor (BDNF) on the intracellular Ca²⁺ concentration (Ca²⁺]_i) alterations and smooth muscle α-actin (α-SMA) expression of smooth muscle cells (SMCs) in mice. Methods The α-SMA expression of colonic SMCs in the BDNF^+/- mice was measured by Western blotting, and was compared with that in BDNF^+/+ mice. The expression of tropomyosin-related kinase B (TrkB) receptor was identified in the primary colonic SMCs of the mice by immunofluorescence staining. After administration of BDNF and TrkB receptor antagonists (K252a), the expressions of α-SMA and TrkB-PLC-Ca²⁺ pathway were measured by Western blotting. The alteration ofCa²⁺]_i was measured byCa²⁺]_i imaging. Results The expression of α-SMA was obviously decreased in BDNF^+/- mice compared with that in BDNF^+/+ mice. The TrkB receptor was identified in the SMCs. After administration of BDNF, the expressions of α-SMA, TrkB-PLC-Ca²⁺ signal pathway andCa²⁺]_i increased. K252a could reverse those changes. Conclusion BDNF might induce the alterations ofCa²⁺]_i and α-SMA expression of SMC by TrkB-PLC-Ca²⁺ signal pathway, which might be the mechanism to affect the gut motility.