动物造模 Z-bio 2023-02-08 655

　　Objective The level of skeletal muscle glucose metabolism is an important factor affecting aerobic exercise ability, and the level of skeletal muscle glucose metabolism is regulated by the biological clock. Chrono is a newly discovered biological clock gene in recent years. It can feedback inhibit the transcription of the core biological clock transcription factor BMAL1 to its downstream biological clock target gene, and is considered as the transcription inhibitor of BMAL1. Studies have shown that BMAL1 participates in the regulation of skeletal muscle glucose metabolism, while CHRONO acts as the transcription inhibitor of BMAL1. The effect of CHRONO-BMAL1 pathway on exercise ability and glucose tolerance is unknown. Therefore, this study intends to explore the effect of CHRONO-BMAL1 pathway on glucose tolerance and exercise ability through skeletal muscle specific chrono overexpression mice and wild-type mice, and provide theoretical basis for clarifying the new mechanism of regulating glucose tolerance and affecting skeletal muscle health.

　　Methods There were 20 healthy 8-week-old C57BL/6N wild mice (WT) and 20 skeletal muscle specific chrono overexpression mice (TG), half male and half female. Record the weight and food intake of mice, carry out body composition test, carry out independent activity test, incremental load exercise ability test, glucose tolerance test and grip test on mice, weigh the skeletal muscle of mice, and carry out real-time fluorescence quantitative PCR to detect the mRNA expression of Chrono, MyhcI, MyhcIIa, MyhcIIb, MyhcIIx, Pdha1, and the kit to detect the content of muscle glycogen.

　　Results (1) Compared with WT rats, TG rats' autonomous activity and incremental load exercise ability were significantly decreased (P<0 05 or P<0 01); (2) Compared with WT rats, the weight of gastrocnemius muscle, quadriceps femoris muscle, soleus muscle, extensor digitorum longus muscle and anterior tibial muscle of TG rats increased significantly (P<0 01), the weight of gastrocnemius and quadriceps femoris of TG female rats was significantly lower than that of TG male rats (P<0 01); (3) Compared with WT rats, TG male rats' forelimb grip significantly decreased (P<0 05), the expression of MyhcII mRNA in skeletal muscle also decreased significantly or showed a downward trend, while the grip of TG female rats and the expression of type II mRNA in muscle fibers were significantly higher than those of TG male rats (P<0. 05) 05 or P<0 01); (4) Compared with WT mice, the blood glucose value and the area under the curve of TG mice at each point were significantly higher during the glucose tolerance test (P<0. 05) 01), TG female rats were significantly lower than TG male rats (P<0 01); (5) Compared with WT mice, the content of muscle glycogen in TG mice increased significantly (P<0 05), the expression of Pdha1 mRNA decreased significantly or showed a decreasing trend, while the content of muscle glycogen and the expression of Pdha1 mRNA in TG female rats were significantly higher than those in TG male rats (P<0 05 or P<0 01)。

　　Conclusion The overexpression of Chrono in skeletal muscle can reduce the spontaneous activity of mice, lead to the reduction of glucose tolerance, and affect the aerobic exercise ability.