Abstract: Objective: To observe the role of apelin in the prevention of pulmonary hypertension induced by hypoxia in mice.Methods: Adult male apoE gene knockout (apoE-KO) mice were exposed to isobaric hypoxic chamber (9%~11% O₂, regular chow feed, 23 h/d)for 3 weeks to establish hypoxia-induced pulmonary hypertension. Thirty apoE-KO mice were randomly divided into normoxia group, hypoxia group and hypoxic with apelin (10 nmol/(kg·d), ip) group. The concentrations of high density lipoprotein (HDL), low density lipoprotein (LDL)and total cholesterol in plasma were detected by Elisa method. The mRNA levels of ATP-binding cassette transporter A1(ABCA1), low density lipoprotein receptor (LDLR), scavenger receptor class B1 (SR-B1), and HMG-CoA reductase (HMGCR)in liver were measured by real-time PCR. The protein level of peroxisome proliferators-activated receptor gamma (PPARγ) in lung was measured by Western blot.Results: ①The right ventricular systolic pressure (RVSP) and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) of hypoxia group were significantly higher than those of normoxia group by 87% and 85% (P<0.05), respectively. RVSP and RV/(LV+S) of apelin group were significantly lower than those of hypoxia group by 39% and 33%(P<0.05), respectively. ②The plasma concentration of HDL and HDL/LDL of apelin group were significantly higher than those of hypoxia group by 21% and 20%(P<0.05), respectively. ③The mRNA levels of LDLR, SR-B1 and ABCA1 in liver of apelin group were significantly up-regulated than those of hypoxia group by 241%, 112% and 69% (P<0.05), respectively, while the mRNA level of HMGCR was down-regulated by 45% (P<0.05). ④The protein level of PPARγ in lung of apelin group was significantly up-regulated than that of hypoxia group by 47% (P<0.05).Conclusion: Apelin attenuates hypoxia-induced pulmonary hypertension of mice through regulation of lipid metabolism.

Key words: apelin, lipid metabolism, pulmonary hypertension, hypoxia, mice