Effects Of The Hypoxic Exercise On AMPK-PGC-1α With Downstream Factors In The Skeletal Muscle Of Obesity Rats

With the improvement of people’s living standards, the dietary habits tend to be high-fat and high-sugar, which tend to cause lipid metabolism disorders, and then the obese has gradually become a global, epidemic disease, including China. Obesity is accompanied constantly by lipid metabolic disorders, imbalances of fatty acid oxidation in skeletal muscle, disorder of adipocyte differentiation and so on. Skeletal muscle determines the body energy metabolism as important sport organ, the steady-state of which is important to maintain the health of skeletal muscle, even the whole body. The studies have found that exercise can reduce blood lipid, blood glucose and improve the fatty acid oxidation metabolism of skeletal muscle effectively, and studies have found that hypoxic exercise affects the fatty acid oxidation in skeletal muscle effectively. AMPK is the energy receptor of the skeletal muscle, PGC-1α plays an important role in the fatty acid oxidation metabolism of skeletal muscle. AMPK can activate PGC-1α to enhance mitochondrial biogenesis and promote fatty acid oxidation in the skeletal muscle as an important regulatory factor of PGC-1α. However, it is unknown whether hypoxic stimulation or hypoxic exercise affects AMPK/PGC-1α with downstream factors in the skeletal muscle of rats with alimentary obesity.Objective: The study constructed the obesity model and hypoxic exercise model by high-fat diet to observe the effect of hypoxic stimulation or hypoxic exercise on the signaling pathway of AMPK/PGC-1α and its downstream factors. We also discussed the adaptive regulation of fatty acid oxidation metabolism of skeletal muscle by AMPK/PGC-1α and its downstream factors under hypoxic stimulation or hypoxic exercise for controlling the weight and improving the fat metabolism by hypoxic stimulation or hypoxic exercise.Methods: 100 healthy male SD rats were randomly divided into 2 groups: normal diet control group(20) and high-fat diet modeling group(80), after 7 weeks high-fat diet, the modle of alimentary obesity rats is constructed successfully, they were randomly divided into 6 groups(N=10): Nomoxic group(A), Nomoxic group combined with endurance exercise(AE), 16.3% hypoxic group(B), 16.3% hypoxic group combined with endurance exercise(BE), 13.3% hypoxic group(C), 13.3% hypoxic group combined with endurance exercise(CE); and they continued to receive high-fat diet. The groups with exercise underwent treading running for 8 weeks, going with 20m/min, 40min/d, 5d/w. Twenty four hours after the last exercise, we killed the rats and detected blood lipid, blood glucose, and the levels of leptin and adiponectin by ELISA.We dectected the protein levels of PGC-1α, AMPK, p AMPK, PPARα and Lipin1 by Western blot and the protein localization of PGC-1α, p AMPK, PPAR α, Lipin1 by immunohistochemistry. Furthermore, we dectected the m RNA levels of PGC-1α, PPARα, Lipin1, CPT-1, MCAD and PPARγ by q RT-PCR.Results: 1) Index of model of alimentary obesity rats: High-fat diet for 7 weeks increased the body weight, BMI of rats, while a series of blood index such as BG, CHO, LDL-c and TG increased significantly, the modle of alimentary obesity rats is constructed successfully.2) Index of blood and morphology after hypoxic intervention and hypoxic exercise: From the second week, hypoxic exercise can control the weight effectively than the hypoxic intervention or endurance exercise, besides this, it can improve the BMI and the epididymis fat percentage as well. The levels of leptin and adiponectin of different hypoxic exercise groups increased very significantly(P<0.01). After the intervention of hypoxic exercise, the levels of blood glucose and blood lipid of different hypoxia exercise groups decreased very significantly or decreased significantly(P<0.01 or P<0.05).3) The result of immunohistochemistry showed that all the positive products of p AMPK, PGC-1α, PPARα and Lipin1 were dark brown, and they were reunion distribution or sporadic-like distribution in the cytoplasm, the distribution or positive staining appeared differently accompanying with different intervention methods.4) The results of Western blot showed that there is very statistical significance between A group and CE group in the phosphorylation level of AMPK of skeletal muscle(P<0.01), and the same as between B group and CE group; there is statistical significance between AE group and CE group in the phosphorylation level of AMPK of skeletal muscle(P<0.05). There is statistical significance between A group and AE group in the protein expression of PGC-1α of skeletal muscle(P<0.05), and there exsits the same statistical significance, such as between A group and BE group, between AE group and CE group, between B group and BE group, between C group and CE group; There is very statistical significance between A group and CE group in the protein expression of PGC-1α of skeletal muscle(P<0.01), and the same as between B group and CE group. There is very statistical significance between A group and CE group in the protein expression of PPARα of skeletal muscle(P<0.01); There is statistical significance between A group and AE group in the protein expression of PPARα of skeletal muscle(P<0.05), there exsits the same statistical significance, such as between A group and C group, between B group and CE group, between BE group and CE group. There is statistical significance between A group and CE group in the protein expression of Lipin1 of skeletal muscle(P<0.05).5) The result of q RT-PCR showed that there is very statistical significance between A group and CE group in the m RNA level of PGC-1α of skeletal muscle(P<0.01), and there exsits the same statistical significance, such as between AE group and CE group, between B group and CE group, between BE group and CE group, between C group and CE group. There is statistical significance between A group and CE group in the m RNA level of PPARγ of skeletal muscle(P<0.05), and the same as between B group and C group; there is statistical significance between B group and CE group in the m RNA level of PPARγ of skeletal muscle(P<0.01). There is very statistical significance between A group and CE group in the m RNA level of MCAD of skeletal muscle(P<0.01), and there exsits the same statistical significance, such as between AE group and CE group, between B group and CE group, between BE group and CE group, between C group and CE group. There is very statistical significance between A group and CE group in the m RNA level of CPT-1 of skeletal muscle(P<0.01), and there exsits the same statistical significance, such as between AE group and CE group, between B group and CE group, between C group and CE group; there is statistical significance between BE group and CE group in the m RNA level of CPT-1 of skeletal muscle(P<0.05). There is statistical significance between A group and CE group in the m RNA level of PPARα of skeletal muscle(P<0.05); there is very statistical significance between B group and CE group in the m RNA level of PPARα of skeletal muscle(P<0.01). There is statistical significance between A group and B group in the m RNA level of Lipin1 of skeletal muscle(P<0.05), and there exsits the same statistical significance, such as between AE group and B group, between AE group and CE group, between B group and BE group, between BE group and CE group; there is very statistical significance between B group and CE group in the m RNA level of Lipin1 of skeletal muscle(P<0.01), and the same as between C group and CE group.Conclusion:1. Different concentrations of hypoxic intervention and/or exercise can inhibit the body’s absorption of food, improve the blood glucose and blood lipid, and promote the expression of leptin; Hypoxic intervention can reduce the expression of adiponectin, and hypoxic exercise promote the expression of adiponectin.2. Hypoxic exercise improves the structure of skeletal muscle of alimentary obesity rats. It may be one of mechanisms that hypoxic intervention and hypoxic exercise both can up-regulate the expression of AMPK and PGC-1α to improve the lipid metabolism of alimentary obesity rats.3. It may be one of mechanisms that hypoxic exercise can up-regulate the expression of the m RNA of PGC-1α with downstream factors(PPARγ、MCAD、CPT-1、PPARα�'� Lipin1) and down-regulate the protein expression of Linpin1 to improve the lipid metabolism of alimentary obesity rats.