低压性低氧暴露后大鼠骨骼肌过氧化物酶增殖激活受体-δ基因表达上调

Hypobaric Hypoxia Exposure Improves PPAR-δ mRNA Expression in Rat Skeletal Muscle

目的探讨低压性低氧暴露对大鼠骨骼肌过氧化物酶增殖激活受体δ(PPAR-δ)基因表达的影响。方法40只SD大鼠随机均分为平原组(H0组)、缺氧1d组(H1组)和缺氧15d组(H15组)。将缺氧组大鼠置于模拟海拔5,000m低压氧舱内,每天23h。平原组大鼠在平原动物房内饲养。分别于缺氧1d和15d后取双后肢腓肠肌,观察腓肠肌毛细血管密度的变化,用同位素标记法测定脂肪酸氧化率,化学比色法测定非酯化脂肪酸(NEFA)含量,RT-PCR法检测骨骼肌中PPAR-δ以及脂肪酸易位蛋白(FAT/CD36)mRNA表达的变化,并与H0组对照。结果①缺氧暴露15d后骨骼肌毛细血管密度增加。②骨骼肌NEFA含量缺氧组显著高于平原对照组(P均<0.05),H1显著低于H15(P<0.05)。骨骼肌脂肪酸氧化率H15显著高于H0和H1(P均<0.05),H0与H10之间无显著性差异。③骨骼肌H1组PPAR-δmRNA表达水平较H0和H15组分别下调39.4%和30.0%(均P<0.05),H0和H15组间无显著性差异。H15组CD36mRNA表达水平较H1组上调12.2%(P<0.05),H0和H15组间以及H0和H1组间无显著性差异。结论慢性高原暴露时骨骼肌PPAR-δmRNA表达上调,这可能是慢性高原暴露时脂肪酸氧化利用增强及骨骼肌毛细血管密度增加原因之一。

Objective To investigate the effects of hypobafic hypoxia exposure on PPAR - 8 （peroxisome proliferate activated receptor delta, PPAR - δ） mRNA expression in skeletal muscle in rats. Methods Spragne Dawley rats were divided into three groups randomly： control group （H0）, hypoxic ld （H1） and hypoxic 15d （ H15）. Animals of H1 and 15 groups were exposed to hypobaric hypoxia chamber simulating 5000m high altitude for ld, 15d respectively, 23h per day. H0 group stayed outside of chamber. The expression of PPAR - δ and CD36 （ fatty acid translocase） genes were measured by RT - PCR. The level of fatty acid oxidation and the content of non - esterified fatty acids （NEFA） were assayed in rat skeletal muscle. Results ①15 - day hypoxic exposure resulted in an increase in capillary density of skeletal muscle.②Compared with H0, the NEFA level of all hypoxia groups increased significantly （P〈0.05）, H1 is lower than H15, The rate of fatty acid oxidation in H30 was significantly higher than in H0 and H1 （ P 〈 0.05）, while there was no significant difference between H0 and H1 （P〈0.05）.③The expression of PPAR-δ mRNA in skeletal muscle of H1 was lower 39.4% and 30.0% than that of H0 and H15 respectively（P〈0.05）, while there was no significant difference between H0 and H15. The expression of CD36 mRNA in H15 was 12.2% higher than that in HI, while there was no significant difference between H0 and H15 or H0 and H1. Conclusion The upregulation of PPAR-δ gene in rat skeletal muscle might be an important factor in the increase of utilization of fatty acid oxidation and capillary density after chronic hypobaric hypoxia exposure.