丝裂原活化蛋白激酶调节缺氧诱导因子1α对大鼠缺氧性肺动脉高压的作用

目的探讨丝裂原活化蛋白激酶(MAPK)和缺氧诱导因子1α(HIF-1α)的表达变化在缺氧性肺动脉高压(HPH)中的作用和意义。方法40只成年雄性Wistar大鼠随机分为对照组(C组)和低氧3、7、14、21d组(H3、H7、H14、H21组),每组8只,低氧组复制HPH大鼠模型。测各组大鼠平均肺动脉压(mPAP)、右室肥大指数(RVHI)、血管形态学指标;Westernblot或免疫组化检测磷酸化细胞外信号调节激酶(pERK)、磷酸化cJUN氨基端蛋白激酶(pJNK)、磷酸化P38(pP38);原位杂交和免疫组化检测HIF1α的表达。结果(1)H7组大鼠mPAP、管壁厚度与血管外径比值及管壁面积与血管面积比值分别为(23.5±1.8)mmHg、(45.5±3.1)%和(54.7±3.2)%,与C组[(16.2±2.0)mmHg、(36.8±2.5)%和(63.2±2.5)%]比较差异均有统计学意义(P均<0.05),H14组稳定于高水平;H14组RVHI为(26.5±2.9)%,与C组[(22.9±2.2)%]比较差异也有统计学意义(P<0.05);(2)pERK蛋白在C组表达不明显,在H3组表达上升,与C组比较差异有统计学意义(P<0.05),且在H3、H7、H14、H21组肺小动脉内膜、中膜表达均为阳性。而pJNK、pP38蛋白在C组与H组表达均不明显;(3)C组HIF1α蛋白表达不明显,H3、H7、H14、H21组肺血管内膜均为阳性,肺血管中膜在H3组表达开始升高(0.209±0.009),与C组比较差异有统计学意

Mitogen-activated protein kinase regulated hypoxia-inducible factor 1α in hypoxia-induced pulmonary hypertension in rats

OBJECTIVE: To investigate the dynamic expression of hypoxia-inducible factor 1alpha (HIF-1alpha) and mitogen-activated protein kinase (MAPK) in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension. METHODS: Forty male adult Wistar rats were randomly divided into five groups:a control group (C group) and groups with hypoxia for 3, 7, 14 and 21 days (H(3), H(7), H(14) and H(21) group), eight rats per group. Mean pulmonary pressure (mPAP), right ventrical hypertrophy index (RVHI) and vessel morphometry were measured. The levels of HIF-1alpha mRNA expression in lung tissue was measured by in site hybridization (ISH). The protein expression of HIF-1alpha and p-ERK, p-JNK, p-P38 were observed by immunohistochemistry or Western blot. RESULTS: The level of mPAP [(23.5 +/- 1.8) mm Hg], the ratio of vascular wall thickness to external diameter [WT, (45.5 +/- 3.1)%] and the ratio of vascular wall area to the total area [LA, (54.7 +/- 3.2)%] were significantly higher in H(7) group than those in C group [(16.2 +/- 2.0) mm Hg, (36.8 +/- 2.5)% and (63.2 +/- 2.5)% respectively, all P < 0.05]. These parameters reached a high level and remained stable on H(14) group, RVHI was significantly higher [(26.9 +/- 1.3)%] on H(14) group than in C group [(23.0 +/- 1.5)%, P < 0.05]. Expression of p-ERK protein in C group was barely positive, but was up-regulated in pulmonary arterial tunica intima and tunica media of all hypoxia rats. Expression of p-JNK and p-P38 in C group and hypoxia groups were barely positive. Expression of HIF-1alpha protein in C group was barely positive, but was up-regulated in pulmonary arterial tunica intima of all hypoxic rats. In pulmonary arterial tunica media, the levels of HIF-1alpha protein was markedly up-regulated in H(3) group (0.209 +/- 0.009, P < 0.05), reaching its peak at H(7) group (0.232 +/- 0.008, P < 0.05), then tended to decline in H(14) group and H(21) group. HIF-1alpha mRNA staining was barely positive in C group, H(3) group and H(7) group, but began to increase significantly at H(14) group (0.305 +/- 0.104, P < 0.05), then remained stable in pulmonary arterial tunica intima. Linear correlation analysis showed that p-ERK, HIF-1alpha mRNA and mPAP were correlated with vessel morphometry and RVHI (P < 0.01); p-ERK was positively correlated with HIF-1alpha mRNA and protein (tunica intima). CONCLUSION: MAPK as a signal transduction may play an important role in the development of hypoxia-induced pulmonary hypertension.