| Background: Coca-Cola is a typical sugar-sweetened soft beverage(SSSB)which have become a part of people’s dietary pattern.Every second,about 10,450 people around the world are enjoying a Coca-Cola beverage.From 2003 to 2014,the per capita consumption of beverage of Chinese residents increased significantly,and the per capita consumption in 2014 was about 10 times of that in 2003,it is increasingly common for children to drink SSSB.Epidemiological studies shown that long-term consumption of SSSB in children and adolescents showed significant abnormal emotional behavior,such as feeling sad and desperate,inattention,fighting and even suicidal thoughts and actions.And there was a J-type-response relationship between the intake of SSSB and mental disorders of children and adolescents.It is reported that there exists a relationship between learning and memory decline result from over consumption of SSSB and adenosine receptors(ARs)metabolic disorder in hippocampus.ARs is one of a family member of G protein-coupled receptors(GPCRs),it exerts an important target for the treatment of neuropsychiatric diseases.Clinical studies and animal experiments have found that adenosine receptor 2a(A2aR)metabolism can affect brain function through central monoamine neurotransmitters,neuroinflammation,neurotrophic factors,stress response and other aspects.Studies have shown that the use of A2 aR antagonists can effectively alleviate the incidence of depression,anxiety,Alzheimer’s disease and other neuropsychiatric diseases,and the activation of A2 aR can inhibit the expression of downstream signaling molecules through competitive binding with dopamine receptors and GPCRs.Exercise has an excellent anti-depressant effect,and regular exercise can alleviate the depression of mice.However,the effects of long-term intake of SSSB on depressive behavior and A2 aR signaling pathway metabolism is not clear,whether exercise intervention can improve the depressive behavior induced by SSSB is also unknown.Objective: This study will investigate the effects of SSSB on depressive behavior in mice,and the role of A2aR-mediated signaling pathway in exercise on depression.The aim is to reveal the cause of abnormal emotional behavior of children and adolescents and the corrective effect and mechanism of exercise from the change of diet structure in modern society.Methods32 4-week-old male C57BL/6 mice with body weight ranging from 14 ~16g were bought from SHANGHAI SLAC LABORATORY ANIMAL CO.All the mice were randomly divided into 4 groups,8 in each group,including(1)drinking water and sedentary group(WS): purified water,ordinary feed,sedentary life;(2)Coca cola intake and sedentary group(KS): Coca-Cola,ordinary feed,sedentary life;(3)drinking water and exercise group(WE): purified water,ordinary feed,treadmill exercise;(4)Coca cola intake and treadmill exercise(KE): Coca-Cola,ordinary feed,treadmill exercise.After 1 week of adaptive feeding,WE and KE groups mice into adaptive exercise procedure(1 week),and formal training was conducted from week 3~14.The mice were weighted at a fixed time every week.After 12 weeks of exercise,behavioral tests were performed,including Tail suspension test(TST),Forced swimming test(FST)and Open filed test(OFT).After this,blood,hypothalamus and hippocampal tissues were taken from mice under anesthesia,serum growth hormone(GH),growth hormone release peptide(GHRP)concentration were detected by Elisa.The expression levels of adenosine receptor 2a(A2aR),protein kinase A(PKA),cAMP-response element binding protein(CREB),CREB-related transcription coactivator 1(CRTC1),brainderived neurotrophic factor(BDNF),5-hydroxyptamine(5-HT),monoamine oxidase A(MAO-A),catechol-O-methyltransferase(COMT),interleukin-1β(IL-1β),interleukin 6(IL-6),interleukin 10(IL-10)and c-jun amino acid kinase(JNK)mRNA in hypothalamus were determined by RT-PCR.Western blotting was used to detect the protein expression levels in hippocampus of A2 aR,PKA,CREB,CRTC1 and BDNF.Results(1)Studies of growth situation of mice shown that,compared with WS group,body weight,Lee`s index and serum GH were reduced(p < 0.05),serum GHRP no significantly difference(p>0.05)in KS group;body weight and Lee`s index were very significantly reduced(p<0.01),serum GH and GHRP no significantly difference(p<0.05)in WE group.Compared with KS group,body weight in the third week was significantly reduced(p<0.05),and very significantly increased in 13 th week(p<0.01),Lee`s index was very significantly reduced(p<0.01),serum GH tend to increase(p=0.07),serum GHRP no significantly difference(p>0.05)in KE group.The results showed that SSSB could inhibit the growth of mice and exercise could improve that.(2)Behavior test found that,compared with WS group,struggling time in TST was very significantly reduced(p<0.01),struggling time in FST(p=0.08)and central movement time in OFT(p=0.06)tend to decline,floating time in FST tend to increase(p=0.08),shaking time in TST and border time in OFT no significant difference(p>0.05)in KS group;border time in OFT was very significantly reduced(p<0.01),and an increasing trend of struggling time in FST(p=0.05)and central movement time in OFT(p=0.06),floating time in FST,struggling time and shaking time in TST no significantly difference(p>0.05)in WE group.Compared with KS group,Struggling time in FST and shaking time in TST were very significantly increased(p<0.01),struggling time in TST was significantly reduced(p<0.05),central movement time in OFT tend to increase(p=0.07),floating time in FST tend to decrease(p=0.06),border time in OFT no significantly difference(p>0.05)in KE group.The results showed that SSSB could induce depressive behavior of mice,exercise could improve this situation.(3)Studies on gene and protein level of A2aR-PKA-BDNF signaling pathway found that,compared with WS group,A2 aR,CREB and CRTC1 mRNA level were very significantly increased(p<0.01),BDNF mRNA level were increased(p<0.05),PKA mRNA level no significantly difference(p>0.05)in hypothalamus in KS group;A2aR,CREB,CRTC1 and BDNF mRNA level were very significantly increased(p<0.01),PKA mRNA level was increased(p<0.05)in hypothalamus in WE group.Compared with KS group,CREB mRNA level was significantly increased(p<0.05),BDNF mRNA level tend to increase(p=0.09),A2 aR,PKA and CRTC1 mRNA level no significantly difference(p>0.05)in hypothalamus in KE group.Compared with WS group,A2 aR and PKA protein level were significantly increased(p<0.05),CRTC1 protein level was significantly reduced(p<0.05),CREB and BDNF protein level no significantly difference(p>0.05)in hippocampus in KS group;PKA and CREB protein level were significantly increased(p<0.05),A2 aR,CRTC1 and BDNF protein level no significantly difference(p>0.05)in hippocampus in WE group.Compared with KS group,A2 aR and PKA protein level was very significantly reduced(p<0.01),BDNF protein level was very significantly increased(p<0.01),CRTC1 protein level was significantly increased(p<0.05),CREB protein level tend to increase(p=0.08)in hippocampus in KE group.It was shown that SSSB induced the disturbance of downstream signaling pathway by activating A2 aR,exercise could improve the level of CRTC1 and BDNF protein caused by A2 aR.(4)Studies on monoamine neurotransmitter related genes found that,compared with WS group,COMT mRNA level was very significantly increased(p<0.01),5-HT1 A and MAO-A mRNA level no significantly difference(p>0.05)in hypothalamus in KS group.COMT mRNA level was very significantly increased(p<0.01),MAO-A mRNA level was significantly increased(p<0.05),5-HT1 A mRNA level tend to increase(p=0.07)in hypothalamus in WE group.Compared with KS group,5-HT1 A mRNA level tend to increase(p=0.06),MAO-A and COMT mRNA level no significantly difference(p>0.05)in hypothalamus in KE group.The gene level of A2 aR was significantly positively correlated with 5-HT1 A and COMT mRNA(p<0.01)and no significantly correlation with MAO-A mRNA level(p>0.05)in hypothalamus.The results suggest that the effects of SSSB on depressive behavior might be related to the abnormal increase of A2 aR gene level induced by the disorder of monoamine neurotransmitter related genes.(5)Studies of central inflammation found that,compared with WS group,IL-1β mRNA tend to increase(p=0.08),IL-6,IL-10 and JNK mRNA no significantly difference(p>0.05)in hypothalamus in KS group.IL-1β and IL-10 mRNA were significantly increased(p<0.01),JNK mRNA was significantly reduced(p<0.05),IL-6 mRNA tends to increase(p=0.06)in hypothalamus in WE group.Compared with KS group,IL-1β,IL-6,IL-10 were significantly increased(p<0.05),JNK mRNA were significantly increased(p<0.01)in hypothalamus in KE group.The mRNA level of A2 aR was significantly positively correlated with IL-1β,IL-6,IL-10(p<0.01)and positively correlated with JNK mRNA(p<0.05)in hypothalamus.It was suggested that the effects of SSSB on depressive behavior may be related to the abnormal increase of A2 aR gene expression induced by the increased level of inflammation factors.Conclusion(1)Long-term consumption of SSSB increased the depressive behavior in mice,regular exercise can improve the depressive behavior.(2)Depressive behavior caused by long-term consumption of SSSB may related to the abnormal expression of molecules in A2aR-PKA-BDNF signaling pathway,regular exercise can decrease the protein level of A2 aR and activate the PKA-BDNF signaling pathway,thus improving the depressive behavior.(3)The expression level of A2 aR in hypothalamus was positively correlated with 5-HT1 A,COMT,and inflammatory factors,indicating that SSSB and exercise had an impact on depressive behavior,and were related to the level of monoamine neurotransmitters and neuroinflammation.Significance: In this study,we investigated the effect of SSSB as an unhealthy diet on depressive behavior in mice and the mediating mechanism of A2aR-PKA-CREB signaling pathway in exercise on depression.On this basis,the correlation between the expression level of A2 aR gene and monoamine neurotransmitters and central inflammatory factors was further explored,and it was found that SSSB induced A2 aR signal transmission disorder may be related to the abnormal expression of monoamine neurotransmitters and central inflammatory factors.The results will provide theoretical basis for the study of exercise on depression and clinical antidepressant therapy. |
PDF Full Text Request