The Effects Of Preadipocyte Differentation And Proliferation In The Formation And Prevention And Treatment Of Obesity By Exercise

The increase or reduction of body fat were accompanied with the hypertrophy or reduction of the fat cells volume respectively,and it is not sure whether the number of fat cells will also change accordingly.However,the fat cells kept continuously changing and renewing during the lifetime.Preadipocyte differentiation and proliferation played important roles in both fat cells number change and fat cells turnover,which were closely related to the morphology and function of fat cells.Therefore,it may be a breakthrough that discussing the effects of the preadipocyte proliferation and differentiation on the adipocytes morphological and functional from cellular dynamics insight to reaseach the obesity and obesity-related complications.The present study was to simulating the processes of human obesity formation and obesity prevention by high fat diet and exercise respectively in Sprague-Dawley rats.The experiments in vivo and in vitro were producted to examine the preadipocyte proliferation and differentiation ability when the body fat changed,and discuss the influences of the preadipocyte proliferation and differentiation on the fat cells number and fat cell renewal combining with the changes of fat cell volume and number from the cellular level,and revealed its effects in the obesity formation by high-fat diet and the prevention and treatment of obesity by exercise.The blood indicators and genes expression of fatty acid metabolism were measured to analysis the relationship among preadipcyte proliferation and differentiation,fat cell renewal and fat cells function,which provided theoretical for the prevention and treatment of obesity and related complications.The experiment is divided into two parts:experiment in vivo and experiment in vitro.Study 1:The Roles of the Preadipocyte Proliferation and Differentiation on the Formation and Prevention and Treatment of ObesityObjective:To analysis the effects of preadipocyte proliferation and differentiation on the number of fat cells and fat cell turnover from the cellular level,and reveal their roles on the obese formation by high fat diet and the prevention and treatment of obesity by exercise in rats.Methods:Two stages were included in the experiment in vivo:the first stage was the experimental on the formation and prevention of obesity,and the second phase was the experimental on fat loss by exercise.120 Sprague-Dawley male rats(4 weeks age)were involved in the first stage,30 rats from which were selected randomly and epually divided into 3 groups:normal control group(NC group),normal exercise group(NE group),high fat diet exercise group(HE group).The other 90 rats were fed with high fat diet.12 weeks later,42 rats meet obesity standard,and 8 rats were randomly selected from which as high fat diet model group(HC Group),the other 34 obese rats were used in the second stage and randomly divided into 4 groups:obese normal dietary sedentary group(HNC group,n=8),obese normal diet exercise group(HNE group,n=8),obese high fat diet sedentary group(HHC group,n=8)and obese high fat diet exercise group(HHE group,n=10),all rats were underwent a 10 weeks intervention.Rats were fed with the normal chow and high-fat chow restpectively and trained on the treadmill.Each stage after the end of the experiment,6 rats were selected randomly in each gooup and executed for collect the blood to test blood indicators;histological methods combined with serological was used to detect the size and number of fat cells;Western Blot was used to detect PPAR?,C/EBP? and Capase-3 protein expression,RT-PCR was used to detection the expression of LPL mRNA,HSL mRNA and FAS mRNA in fat tissue.Results(1)Body morphology indicators? Normal ratsNo significant differences were found for body length among grouops in normal rats.The body weight,abdominal total fat mass and Lee'S index of the HC group were significantly higher than those of the NC and HE groups.Percentage of body fat of NC and HC groups were significantly higher than those of the NE(P<0.01)and HE(P<0.01)Groups respectively.Exercise changed the composition percentage of the intraperitoneal fat.? Obese ratsNo significant difference were found for body length among grouops in obese rats.The body weight of the HHC group was significantly higher than that of the HNC group which was significantly higher than that of the HNE group.Lee's index of the HHC group was significantly higher than that of the HHE group.Abdominal total fat mass and body fat percentage of the HNC and HHC groups were significantly higher than those of the HNE and HHE groups respectively.(2)Blood indicators? Normal ratsThere was no significant difference for Serum GLU among groups in normal rats.Serum INS,FFA,LDL,TNF-a and IL-6 were significantly higher in the HC group than those in the NC and HE groups.The ISI and HDL of the HC group were significantly lower than those of the NC and HE groups.Serum TC of the HE group was significantly higher than that of the HC group.? Obese ratsThere was no significant difference for Serum GLU among groups in obese rats.Serum INS and FFA of the HNC and HNE groups were higher than those of the HNE and HHE groups respectively.The TQ TNF-? and IL-6 of the HHC group were significantly higher than those of the HNC and HHE groups.The ISI of the HNE and HHE groups were significantly higher than that of the HNC and HHC groups.In addition,the HDL of the HNE group was significantly higher than that of the HNC group;and the LDL of the HHC group was significantly higher than that of the HHE group.(3)The number and average diameter of fat cells? Normal ratsThe total fat cell number of intraperitoneal fat of the HC was significantly greater than that of the NC group.The adipose cell average diameter of the HC group was greater than that of the HE group in Epididymis,Kidney and abdominal fat.The adipose cell average diameter of the NC group was greater than that of the NE and HE groups,and the HC group was greater than that of the HE group.? Obese ratsThere were no significant difference for fat cell number in epididymis,Kidney,abdominal fat and the total number among groups in obese rats.In three parts,the adipose cell average diameter of the HNE group were significantly smaller than those of the HNC group,and the HHE group was significantly smaller than that of the HHC and HNC groups.(4)The relative expression of protein? Normal ratsPPARy:the relative expression of PPARy of the NE and HC groups were significantly higher than those of the NC group in epididymis,kidney and abdominal fat;the relative expression of PPARy of the HC group were significantly higher than those of the HE group in kidney and abdominal fat.C/EBPa:the HC group was significantly higher than the NC group in the epididymis fat.In the kidney fat,the NE group was significantly higher than that of the NC group,the HC group was significantly higher than those of the NC and HE groups,the NE group was significantly higher than that of the NC group in abdominal fat.Caspase-3:the NE and HE groups were significantly higher than those of the NC and HC groups in epididymis fat respectively,the NE group was significantly higher than that of the NC group in kidney fat.? Obese ratsPPARy:There were no significant difference among groups in both epididymis and abdominal fat in obese rats.The expression of PPARy of the HHE group was significantly higher than those of the HNC,HNE and HHC groups,the HHC group was significantly higher than that of the HNC group.C/EBPa:The HHC and HNE groups were significantly higher than the HNC group in epididymal fat.The HNC group was significantly lower than the HHC which was significantly lower than the HHE Group in kidney fat,the HNC group was significantly lower than the HHC Group in abdominal fat.Caspase-3:There were no significant difference among groups in both epididymis and abdominal fat in obese rats.The HNE and HHE groups were higher than the HNC andHHC groups in kidney fat respectively.(5)Results of mRNA test? Normal ratsLPL mRNA:The HC group was significantly higher than the NC group which was significantly higher than the NE group in all parts of fat.HSL mRNA:The NE and HE groups were significantly higher than the NC and HC groups in all parts of fat respectively.FAS mRNA:The HC group was significantly higher than the NC group which was w significantly higher than the NE group in all parts of fat,the HC group was significantly higher than the HE group.? Obese ratsLPL mRNA:the HNE group was significantly lower than the HNC and HHE groups in all parts fat,and the HHC group was significantly higher than the HNC group.HSL mRNA:the HNE group was significantly higher than the HNC,HHE,HHC groups,and the HHE group was significantly higher than the HHC group.FAS mRNA:the HNC and HHC groups were significantly higher than the HNE and HHE groups respectively,the HHC group was significantly higher than the HNC group.Study 2 The Effects of High-Fat Diet or Exercise on the Preadipocyte Proliferation and Differentiation in VitroObjective:To compare the proliferation and differentiation of the preadipocyte extracted from the epididymis and abdominal fat in both normal and obese rats in primary culture.Method:The groups were same with stduy 1.Two rats of ecch groups were used to extract the preadipocyte from the epididymis and abdominal fat,then the preadipocyte were used in primary culture.Cell groups included the normal rats(NC group,NE group,HC group,HE group)and the obese rats(HNC group,HNE group,HHC group,HHE group).After passage once,all preadipocyte was counted with the blood cell counter,the draw the growth curve and calculate the double time.Resuls? Normal ratsThe DT values of the NE and HC groups were significantly lower than that of the NC group in Epididymis and abdominal fat,and the DT value of the HE group was significantly lower than that of the HC group in abdominal fat.? Obese ratsThe DT values of the HNE and HHE groups were significantly lower than those of the HNC and HHC groups in Epididymis and abdominal fat respectively,and the DT value of the HHC group was significantly lower than that of the HNC group in Epididymis fat.Conclusions(1)The preadipocyte proliferation and differentiation ability inceased in both high-fat diet induced obesity and the prevention and treat of obesity by exercise,but the mechanism is different.The former was compensatory mechanism and the later was adaptive mechanism.(2)The preadipocyte proliferation and differentiation played roles through affecting the fat cell numbers and the fat cells renewal in the formation and prevention of obesity.(3)The preadipocyte differentiation and proliferation may play a role in improving subcutaneous and visceral fat distribution,and the mechanisms need to be further studied.(4)The proliferation ability of the preadipocyte extracded from the epididymis and abdominal fat was significantly facilitated by high-fat diet and exercise interventions,which can expand the preadicyte capacity and increase the risk of obesity.There were difference for preadipocyte proliferation and differentiation between in vitro and in vivo.And the preadipocyte proliferation and differentiation were closely effected by their survival condtions.