| Objective: To observe the effects of metformin on pulmonary arterial pressure,pulmonary arterial structure and function of pulmonary arterial hypertension(PAH)induced by monocrotaline(MCT),and to explore the possible mechanism of metformin for MCT-induced-PAH.Method: Forty-eight male Sprague-Dawley rats(150-200g)were randomly divided into three groups:normal control group(CTRL,n=16),PAH group(PAH,n=16),metformin group(MET,n=16).PAH and MET rats received intraperitoneal injection of MCT(20mg·kg-1·w-1)to induce PAH once a week for two week.MET were given daily intragastric metformin(100mg·kg-1·d-1).CTRL were administrated with equal volume of 0.9% sodium chloride solution by intragastric for 4 weeks.The mean pulmonary arterial pressure(m PAP)were measured by right heart catheterization.The right ventricular hypertrophy index(RVHI)was calculated by weighing method.The morphological changes of pulmonary arterioles were observed by HE staining.The ratio of wall/total thickness index(WT%)and ratio of wall/total area index(WA%)in small pulmonary arteries were calculated by graphical analysis.Pulmonary arteriole ring tension experiment was performed to observe vascular endothelium-dependent relaxation(EDd R)function and endothelium-independent relaxation(EDi R)function and vascular contraction function in vitro.The expression of LC3 II/I in lung tissue was detected by immunohistochemistry.The level of protein Beclin1,LC3II/I,AMPK and P-AMPK in the lung tissue were detected by Western Blot.Results:(1)Compared with CTRL,m PAP and RVHI were significantly increased in PAH and MET,while those were lower in MET than PAH.(m PAP:CTRL:20.79±1.92 mm Hg,PAH:34.43±2.78 mm Hg,MET:27.76±1.98 mm Hg;RVHI:CTRL:20.88±3.44%,PA H: 48.77±7.06%,MET: 31.96±6.08%;all p <0.05).(2)Compared with CTRL,WA% and WT% were significantly increased in PAH and MET,while those were lower in MET than PAH.(WA%:CTRL: 51.13±4.33%,PAH: 79.79±3.06%,MET: 61.59±7.16%.WT%:CTRL: 30.00±3.35%,PAH: 52.96±3.87%,MET: 40.17±6.17% all p <0.05).(3)Compared with CTRL,expression of LC3 II/I in pulmonary arteriole was significantly increased in PAH and MET,while those were higher in MET than PAH.(CTRL:20.54 ± 6.05,PAH: 35.60 ± 2.74,MET:52.57 ± 4.41,all p <0.05).Compared with CTRL,expression of PCNA in pulmonary arteriole was significantly increased in PAH and MET,while those were lower in MET than PAH.(4)Compared with CTRL,the expression of Beclin1 and LC3II/I in the lung tissue was significantly increased in PAH and MET,while those were higher in MET than PAH.(Beclin1/β-actin: CTRL:0.20±0.09,PAH: 0.42 ± 0.14,MET: 0.42±0.14;LC3II/I: CTRL: 1.22 ± 0.26,PAH:1.46 ± 0.27,MET:1.79 ± 0.31,all p <0.05).Compared with CTRL,the expression of P-AMPK/AMPK in the lung tissue was significantly increased in PAH and MET,while it was higher in MET than PAH.(CTRL:1,PAH: 4.15±1.33,MET: 8.63 ±1.82,all p <0.05).(5)Compared with CTRL,the EDd R of PAH rats in pulmonary arteriole was significantly decreased in PAH and MET,while those were higher in MET than PAH.(p D2:CTRL:7.05±0.84,PAH:4.33±0.82,MET:6.10±1.97,all p <0.05);Compared with CTRL,the EDi R of PAH rats in pulmonary arteriole was significantly decreased in PAH and MET,while those were higher in MET than PAH.(p D2:CTRL:8.02±0.34,PAH:5.76±0.48,MET:6.56±0.56,all p <0.05).There was no significant difference in vascular contraction function between three groups(all p >0.05).Conclusions: Metformin can improve m PAP as well as pulmonary vascular structure and function in MCT-induced PAH rats.The mechanism may be related to metformin activates AMPK and induced autophagy,and inhibiton of proliferation of pulmonary arterioles smooth muscle cells. |
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