Effects Of Exercise And Restriction Of Energy Intake In A Cold Environment On Ghrelin And Its Receptor GHS-R In Obese Rats

Objective: Exercise in a cold environment resulted in significant weight loss in rats,but changes in appetite hormones due to the principle of energy balance resulted in a significant increase in food intake,suggesting that weight loss is difficult to achieve without food restriction.In this study,we investigated the changes in food intake,body weight,visceral adiposity,lipids,serum Ghrelin,Leptin,NPY concentration,Ghrelin,Goat,GHS-R m RNA and protein expression in gastric tissues and hypothalamus of nutritionally obese rats through 5 weeks of cold exercise combined with energy intake restriction intervention.This study was conducted to investigate the relationship between changes in body composition and appetite-related hormone levels in obese rats induced by exercise and energy restriction in cold environments,to elucidate the effects of appetite-related hormones and the Ghrelin/Goat/GHS-R system on the regulation of body energy balance,and to provide a theoretical basis for the prevention and treatment of obesity by cold exercise.Methods: The rats were fed a 45% fat-fed high-fat diet for 8 weeks to establish a nutritional obese rat model.48 rats were randomly divided into 6 groups of 8 rats each,including the normothermic quiet group(NC),normothermic exercise group(NE),cryogenic quiet group(LC),cryogenic exercise group(LE),cryogenic restricted energy intake quiet group(LCR)and cryogenic restricted energy intake exercise group(LER).They were first acclimatised for 1 week and then subjected to a 5-week cold environment exercise intervention.In the normothermic group,the rats lived in an ambient temperature of 24℃-26℃,and in the hypothermic group,the living temperature was 3℃-5℃,the humidity was 50-60% in both groups,and the ambient light-dark cycle was 12h:12h;the rats in the exercise group were trained every other day by running on a platform at a speed of 25 m/min,divided into 2 groups/d,30min/group,with 10 min intervals between groups,lasting 5 wk;the LCR and Blood was collected from the perirenal,epididymal fat,quadriceps,gastrocnemius,stomach and hypothalamus in the abdominal aorta after 5 weeks of intervention,and the four lipids were measured using an automatic biochemical analyser,and the serum Ghrelin,Leptin and NPY were measured by Elisa.Ghrelin,Goat and GHS-R were detected by RT-q PCR and Weatern-blot.SPSS 26.0 and Graph Pad Prism 8.0.2 were used for statistical analysis and graphing of the data.One-way ANOVA was used between groups,three-way ANOVA was used for the interaction of factors,and Pearson correlation analysis was used for correlation between indicators,with P<0.05 indicating a significant difference and P<0.01 indicating a very significant difference.Result:(1)The intake of the NC and NE groups did not fluctuate significantly during the 5-week experimental;the intake of the LC and LE groups started to increase significantly at week 3(P<0.01),and the LCR and LER groups were fed at the daily intake of the NC and NE groups respectively,with no difference between the two groups.(2)After the 5-week experiment,the results of the three-way ANOVA showed that exercise had a significant effect on body weight and visceral adiposity(P<0.01),and temperature and diet had a significant effect on body weight and visceral adiposity(P<0.05).Analysis of gastric weight changes in rats showed that there was a significant interaction between exercise and temperature on gastric weight changes(P<0.01).The morphological results of the gastric fundic gland principal cells showed that the NC group had a disorganized and scattered distribution with swollen cells;the NE,LC,LE,LCR and LER groups had a columnar arrangement with relatively neat and regular,dense and uniform distribution of the gastric fundic gland principal cells compared to the NC group.(3)After the 5-week experiment,it was known from the three-way ANOVA that temperature and diet had significant effects on serum HDL-C in rats(P<0.05 and P<0.01,respectively),and from the interaction,it was known that exercise combined with food restriction had significant effects on serum TG and LDL-C in rats(P<0.05).The results of changes in serum related appetite hormones showed that serum Ghrelin was significantly higher in rats in the NE and LC groups compared to the NC group(P<0.01);serum Leptin was significantly lower in rats in the LCR and LER groups compared to the LC and LE groups(P<0.01);and serum NPY was significantly lower in rats in the intervention group(P<0.05,P<0.01).(4)After 5 weeks of experiment,the gastric tissue Goat m RNA expression and hypothalamic GHS-R m RNA expression were significantly increased in the exercise group compared to the NC,LC,LCR and NE,LE and LER groups(P<0.01).As for the interaction effects,there was a significant interaction between exercise and temperature on rat gastric tissue Goat m RNA expression(P<0.01),and a significant interaction between exercise and diet on rat gastric tissue Ghrelin,Goat and hypothalamic GHS-R(P<0.05,P<0.01,P<0.05,respectively);the results of protein expression changes can be seen that exercise and temperature had a significant effect on rat gastric tissue Goat and GHS-R and hypothalamic Ghrelin were significantly interacted by exercise and diet(P<0.01),and Ghrelin,Goat and hypothalamic Ghrelin,Goat and GHS-R were significantly interacted by exercise and diet(P<0.01,P<0.05,P<0.01,P<0.01,P<0.05)in rat gastric tissue.(5)After the 5-week experiment,Leptin was significantly and negatively correlated with food intake(r=-0.3972,P<0.05),while it was very significantly positively correlated with TG(r=0.8561,P<0.01)and very significantly negatively correlated with HDL-C(r=-0.6048,P<0.01);Ghrelin was significantly and negatively correlated with body weight(r=-0.8188,P<0.01),visceral adiposity(r=-0.7721,P<0.01)very significantly negatively,TG(r=-0.6037,P<0.01)very significantly negatively and HDL-C(r=0.1454,P<0.05)significantly positively;Goat was significantly and positively correlated with food intake(r=0.4726,P<0.01)correlation,and Ghrelin was significantly positively correlated with GHS-R protein expression(r=0.6390,P<0.01).Conclusion:(1)The cold environment,exercise or a combination of both reduced body weight and visceral adiposity in obese rats,and the improvement was more pronounced with the addition of restricted energy intake.(2)Cold exercise and energy restriction improved blood lipid levels in obese rats,and correlated with Leptin and Ghrelin levels.(3)Exercise in a cold environment upregulates Ghrelin,Goat,and GHS-R expression,while the addition of restricted energy intake downregulates Ghrelin,Goat,and GHS-R expression,thereby allowing the body to adapt to reduced energy intake.