Regulation Of Lipolysis By Exercise-induced Interleukin-6 Increase

1 PurposeInvestigate the change of related indices to interleulin-6 and receptor system and lipolysis in blood, adipose and muscle during the course of prolonged exercise. Analyze the relationship between interleukin-6 and hormone sensitive lipase in muscle and adipose, Explore the possible mechanisms of lipolysis regulated by exercise-induced interleukin-6 increasing.2 Experimental MethodsThe subjects of this study, male Sprague—Dawley rats, were assigned to the normal (muscle) glycogen groups and controls(exercise+different sugar food treated 24 hours) in the manner of random arrangement, performed a prolonged exercise. The prolonged exercise was 0。incline running on the treadmill at a speed of 18m/min,lasting 90min, then 30m/min lasting 30min.The killing-rats time is the pre-exercise, 30min during exercise, 120min during exercise, 3 hour post-exercise and 6 hour post-exercise, At the same time, eight rats without exercise were taken as blank group. The samples were collected from the blood, quadriceps femoris muscle and adipose from retroperitoneal. The indices were measured including serum interleukin-6,sobule interleukin-6 receptor, glycerol, free fat acid, insulin, growth hormone, leptin and plasma noradrenalin,adrenalin,interleukin-6 receptor mRNA ,hormone sensitive lipase mRNA and activity in muscle and adipose.3 Result1)During the course of the whole exercise, Serum interleukin-6 levels and sobule interleukin-6 receptor increased firstly and decrease then, reached the peak at exercise 120min. Interleukin-6 levels of low glycogen groups were (very) significantly higher than those of normal glycogen group at exercise 30min(P<0.05) and at exercise 120min (P<0.01).Serum glycerol levels increased first and decreased then, the serum glycerol levels of low glycogen groups were significantly higher than those of normal glycogen groups at the exercise 30min(P<0.05),and very significantly higher than those of normal glycogen groups at the exercise 120min and at the post-exercise 3 hour(P<0.01).Serum free fat acid levels increased firstly and decreased then, reached the peak at the exercise 120min.2)Interleukin-6 mRNA expression receptor in the adipose increased by exercise, and increased slowly in the recovery of exercise.Iterleukin-6 receptor mRNA expression in normal glycogen groups were significantly higher than those of low glycogen groups at the pre-exercise(P<0.05), but reverse at the post-exercise 6 hour, Iterleukin-6 receptor mRNA expression of low glycogen groups were very significantly higher. than those of normal glycogen groups(P<0.01).3) Hormone sensitive lipase mRNA expression increase firstly and decrease then in the adipose, and reached the peak at the exercise 120min,and the change of hormone sensitive lipase activity in adipose resembled those of hormone sensitive lipase mRNA expression. Hormone sensitive lipase activity of low glycogen groups were significantly higher than those of normal glycogen groups at the exercise 30min and exercise 120min(P<0.05),and very significantly higher than those of normal glycogen groups post-exercise 3 hour(P<0.01).4) Interleukin-6 receptor mRNA expression in the muscle increase fast firstly and slowly then, Interleukin-6 receptor mRNA expression of low glycogen groups were significantly higher than those of normal glycogen groups(P<0.05).5)Hormone sensitive lipase mRNA expression in muscle increased firstly and decreased then, reached the peak at the exercise 120min, Hormone sensitive lipase mRNA expression of low glycogen groups were significantly higher than normal glycogen groups(P<0.05).The changes of hormone sensitive lipase activity resembled those of hormone sensitive lipase mRNA expression in muscle. hormone sensitive lipase activity of low glycogen groups were very significantly higher than those of normal glycogen groups at the exercise 120min and post-exercise 3 hour(P<0.01).6)Taking the serum insulin, growth hormone, leptin and plasma noradrenalin, adrenalin as control variables, analyzed the serum interleukin-6 and hormone sensitive lipase in adipose and muscle by partial correlation. The results shows that there were no remarkable relationship between serum interleukin-6 levels and hormone sensitive lipase mRNA in adipose(P>0.05);but the partial correlation coefficient of interleukin-6 and hormone sensitive lipase activity was significant at exercise 120min(P<0.05),but was not significant at the other time of exercise in adipose. he partial coefficients between serum interleukin-6 and hormone sensitive lipase mRNA in muscle expression were (very)significant at the exercise 120min and post-exercise 6 hour(P<0.05 or P<0.01),but on the other time, the partial between serum interleukin-6 levels and hormone sensitive lipase mRNA expression were not significant(P>0.05) in muscle. And there were no remarkable relationship between serum interleukin-6 levels and hormone sensitive lipase in muscle(P>0.05).4 conclusionsThe present results indicated that exercise up-regulated the levels of interleukin-6 and sobule interleukin-6 receptor in systemic cycle, and increased the lipolysis in whole body. At the same time, interleukin-6 receptor mRNA expression of adipose and muscle increased and kept the high level during the course of exercise. That suggested that levels of interleukin-6 receptor among membrane increased. That indicted that the increasing of interleukin-6 binding to the membrane activated the cascade reaction of interleukin-6 in cellular level and played the biological role in adipose and muscle. Hormone sensitive lipase mRNA expression and activity increasing were the major reason of lipolysis increase in all body. The result of partial correlation analysis indicated that interleukin regulates the lipolysis directly. The regulating site is hormone sensitive lipase activity in adipose, and hormone sensitive lipase mRNA expression in muscle. It is the peak time of interleukin-6 levels that the partial correlation coefficients were significant, and that indicated that interleukin-6 levels increase lipolysis beyond a threshold level.