Effects Of Aerobic Exercise On Voluntary Activity And Electrical Activity Of VTA-DA Neurons In High Fat Diet Rats

Research objective: With the rapid development of society and economy and the continuous advancement of industrialization,drastic changes have taken place in the human lifestyle and diet structure,which has led to a sharp rise in obesity rates in developed and developing countries,which has affected human Public health issues.Without effective prevention and control measures,the global obesity rate will increase by one-fifth by 2025.A large number of studies have confirmed that physical exercise or improving physical activity has many benefits for the physical and mental health of obese people,including promoting cardiovascular health,improving heart and lung function,and improving brain function.Therefore,improving the level of physical activity is used as an important strategy to prevent obesity and its related diseases.However,the neurobiological mechanism of exercise to prevent obesity is not clear.Recent studies have confirmed that obesity causes plastic changes in the midbrain-striatum dopamine system and reduces physical activity levels.But the exact mechanism is not clear.Therefore,in this study,rats with a high-fat diet were used as experimental subjects.The effects of 6-week aerobic intensity of treadmill exercise on their autonomic activity were observed.The possible mechanism was analyzed from the perspective of changes in dopamine neurons in the ventral tegmental area.Provide experimental basis for improving physical activity of high-fat diet.Research method: Male SD rats(body weight 53.14?6.11g)were adaptively fed for 3 days,and were randomly divided into a common diet group(Chow,n=22)and a high-fat diet group(HFD,n=22)according to their diet.After 10 weeks of feeding,the normal diet group was randomly divided into a normal diet control group(CG,n=10)and a normal diet exercise group(CEG,n=10);the high-fat diet component was the high-fat diet control group(OG,n=10)and high-fat diet exercise group(OEG,n=10).Subsequently,rats in the CEG and OEG groups performed treadmill exercise interventions 5 times a week,40 minutes each,for 6 weeks.The specific plan was: the slope of the treadmill was zero,and the exercise intervention started from 10 m / min,and increased every 2 weeks.2m / min.Each training time is 40 minutes(5min warm-up + 30 min incremental speed + 5 min relaxation),and the warm-up and relaxation speed are 10 m / min.The experiment lasted 16 weeks,During the experiment,body weight and food intake were recorded weekly.The open field test was used to evaluate the autonomic activity of rats.The in vivo multichannel electrophysiological technique was used to observe the changes in the electrical activity of DA neurons in the ventral tegmental area of the brain.The serum Leptin level was measured by enzyme-linked immunosorbent assay.Blot technology was used to detect the expression levels of tyrosine hydroxylase(TH),Signal transducers and activators of transcription 3(STAT3)705 serine site phosphorylation protein in the brain.Finally,measurement data are expressed as mean ± standard deviation.The data of three groups and above were analyzed by two-way analysis of variance(LSD),and the data of two groups were analyzed by T test.The significance level was P <0.05 and the extreme significance level was P <0.01.Research result:(1)Compared with the Chow group,the body weight(P <0.01)and energy intake(P <0.01)of the HFD group were significantly increased;compared with the CG group,the fat rate(P <0.01)and weight change rate of the OG group(P <0.01)<0.05),lee's index(P <0.01)and serum Leptin level(P <0.01)all increased significantly.After exercise intervention,compared with the OG group,the body weight(P <0.01),energy intake(P <0.01),fat rate(P <0.01),weight change rate(P <0.01),lee's index(P < 0.01)and serum Leptin levels(P <0.01)were significantly reduced.(2)Compared with the Chow group,the level of voluntary activity in the HFD group was significantly reduced(P <0.01),and the total distance and average speed of the exercise were significantly lower than those in the Chow group.After 6 weeks of exercise intervention,the level of autonomous activity of the rats in the OEG group was significantly higher than that in the OG group(P <0.05).(3)In the basal state,there was no significant difference in the average firing frequency of DA neurons in the ventral tegmental area of each group.After stimulation with exercise signals,it was found that compared with the CG group,the average firing frequency of DA neurons in the ventral tegmental area of the OG group was significantly reduced(P <0.05).The average firing frequency of DA neurons in the cover area increased significantly(P <0.05);after Leptin injection,it was found that the rate of change in firing frequency was lower in the OG group(P <0.05),while the OEG group found that The rate of change in discharge frequency was higher after injection of Leptin(P <0.05).(4)Compared with the CG group,the TH expression in the midbrain of the OG group was significantly decreased(P <0.05),while the expression of STAT3(Tyr705)was significantly up-regulated(P <0.01).After exercise intervention,compared with the OG group,the expression of TH in the brain in the OEG group was significantly up-regulated(P <0.05),and the expression of STAT3(Tyr705)was down-regulated,the difference was significant(P <0.05).Research conclusion: 6 weeks of aerobic exercise intervention can significantly reduce body weight,improve body composition,increase autonomic activity,improve Leptin resistance and promote midbrain TH expression in high fat diet rats,and inhibit STAT3 signal activity.The 6-week aerobic exercise intervention may increase the level of autonomic activity in rats on a high-fat diet,which may be related to changes in dopamine neurons in the ventral tegmental area of the midbrain.