Study On The Correlation Between Skeletal Muscle Injury Repair And Rhythmic Expression Of BMAL1 And HIF-1?

Object: To observe the relationship between BMAL1 and the recovery of HIF-1 ? rhythm after skeletal muscle injury by detecting the expression of HIF-1 ? and BMAL1 genes in rat soleus muscle at different phases before and after skeletal muscle injury.Methods: 208 8-week-old male Sprague-Dawley rats were randomly divided into group C(blank control group)and group M(model group).The gross condition of the experimental rats was observed,the ultrastructure of skeletal muscle was observed by transmission electron microscopy,the serum CK-MM level of the experimental rats was detected by ELISA,the expression of HIF-1? and BMAL1 genes in skeletal muscle was detected by PCR and WB,the co-expression of HIF-1? and BMAL1 was observed by immunofluorescence.Data were processed using graphpadprism8.0 statistical software as well as the cosine analysis software circacompare.Results: 1.General observation:After model establishment,the motor ability of rats in group M was significantly weakened,the body temperature increased,shortness of breath,mental slack.2.Ultrastructural observation: The ultrastructure of skeletal muscle was damaged in different degrees at 0h-72 h after model establishment: at 0h-48 h after exercise,the myofibrils and mitochondria in group M were disorganized,the mitochondria were swollen,and the ultrastructure of skeletal muscle at 72 h showed that the injury had tendency to recover,which tended to be similar to group C.3.CK-MM content: The serum CK-MM concentration in group M was generally higher than and gradually tended to be higher than that in group C.At 0 h after exercise: the increase in group M was most significantly different from that in group C(P < 0.01);at12 h and 24 h after exercise: the increase in group M was significantly different from that in group C(P < 0.05);at 48 h after exercise: the increase in group M was more significant than that in group C,but there was no statistically significant difference.4.HIF-1? gene expression:(1)Blank group: HIF-1? gene expression from ZT0(8:00)-ZT6(14:00)showed a decreasing trend,and reached the lowest value within 24 hours at ZT5.95(13:57),after which HIF-1? gene expression gradually increased and reached the highest peak within 24 hours at ZT17.95(1:57),followed by a decrease,and the rhythmic trend of HIF-1? gene expression showed a state of first decrease and then increase and then decrease within 24 hours,and within the remaining 48 hours,the changes every 24 hours were similar to those of ZT0-ZT24,showing a trend of first decrease and then increase and then decrease.(2)Model group: The gene expression of HIF-1? did not show a significant rhythmic state within 72 hours;within 72 hours after modeling,the rhythmic changes were different every 24 hours: rhythmic disturbances occurred within 24 hours after injury,the rhythm gradually recovered at 24 hours � 48 hours and basically returned to normal at 48 hours� 72 hours after injury.5.BMAL1 gene expression:(1)Blank group: BMAL1 expression began to decrease at ZT0(8:00),and by ZT11.18(19:10),BMAL1 was at the lowest value during rhythmic changes,followed by an increase in expression and an increase to the highest value at ZT23.18(7:10),after which BMAL1 gene expression returned to ZT24(8:00 the next day),and within the next 48 hours,the daily rhythmic expression of BMAL1 gene was similar to ZT0-ZT24,presenting a total of three complete rhythmic cycles within 72 hours.(2)Model group: The gene expression of HIF-1? within 72 hours was significantly different from that in the blank group and there was no significant rhythmicity;the rhythm changes were different every 24 hours after modeling: rhythm disturbance occurred within 24 hours after injury,the rhythm gradually recovered at 24� 48 hours and basically returned to normal at 48� 72 hours after injury.6.Immunofluorescence co-localization observation: There was no significant coexpression of BMAL1 and HIF-1? at 0 h,6 h and 36 h in the blank model group.7.Expression of HIF-1 ? and BMAL1 protein: The protein expression levels of HIF-1 ?and BMAL1 changed after sports injury,but the histone expression of HIF-1 ? and BMAL1 did not show a rhythmic rule.Conclusion: 1.The gene expression of BMAL1 and HIF-1 ? is rhythmic under normal physiological conditions.2.Exercise injury can lead to disturbances in the rhythmic expression of skeletal muscle clock genes BMAL1 and HIF-1? m RNA.3.The repair process of skeletal muscle injury presents consistency with the recovery process of rhythmic expression of BMAL1 and HIF-1?.3.BMAL1 may be involved in regulating the recovery process of HIF-1? rhythmic disturbance resulting from skeletal muscle injury.