Relationship Between Palmitoleic Acid And Obesity And Hypertension In Chinese Children And Adolescents And The Underlying Mechanisms

Palmitoleic acid(16:1n-7)is a monounsaturated fatty acid with 16 carbons and has been widely found in serum,adipose tissue and liver.The 16:1n-7 was considered to be one kind of "lipokine" since evidence from animal studies demonstrated that it is released from adipose tissue and can exert metabolic effects on distant organs.In recent years,observational studies conducted in human have suggested that 16:1n-7 paly important roles on the development or prevention of chronic diseases including obesity and hypertension.However,evidence from epidemiological studies regarding the relationship between circulating 16:1n-7 and obesity and hypertension remains inconclusive,and evidence from Chinese population is few.The object of the present was to investigate the association between circulating 16:1n-7 and obesity and hypertion.Firstly,a meta-analysis was conduted to investigate the relationship between16:1n-7 and obesity based on existing evidence.Secondly,case-control studies were performed to investigated the association between circulating 16:1n-7 and obesity and hypertension in Chinese children and adolescents.Thirdly,the underlying mechanisms of the effects of 16:1n-7 on obesity and hypertension were explore by animal models.The main findings of the present study were listed as followings:(1)The present meta-analysis included 16 individual stuidies with a total of 452 obese and 456 normal weight participants.Summary results of the meta-analysis showed that obese participants had high levels of circulating 16:1n-7 was significantly higher than normal weight participants(Weighted mean difference(WMD)= 0.16,95%CI:0.05,0.26).However,high heterogeneity was found between included studies(I2 =93.2%,P<0.001).(2)We conducted a case-control study of 1442 obese cases(73.56%males,aged 6-18 years)and 1442 normal-weight controls(73.56%males,aged 6-18 years).Cotronls were matched to cases by age and sex with a 1:1 ratio.We found that obese cases had lower proportions of erythrocyte phospholipid 16:1n-7 than controls(P<0.001).In multivariable-adjusted logistic regression models,erythrocyte phospholipid PLA was found to be inversely associated with obese risk(highest versus lowest quartile OR = 0.47,95%CI:0.28,0.79),while this inverse association was only significant in males or in participants aged 12-18 years,indicating that sex and age could be the confounding factors.(3)A case-control study was conducted to investigate the association between erythrocyte phospholipid 16:1n-7 and hypertension.We included 349 hypertensive cases(61.32%males,aged 6-18 years)and 1396 normotensive controls(61.32%males,aged 6-18 years).We found that hypertensive cases showed lower proportions of erythrocyte phospholipid 16:1n-7 than normotensive controls(P<0.001).In multivariable-adjusted logistic regression models,erythrocyte phospholipid 16:1n-7 was found to be inversely associated with risk of hypertension,while this inverse association was only significant in females or in participants aged 12-18 years,indicating that sex and age could be the confounding factors.(4)In mice model,32 male C57B/L6 mice aged 6 weeks were randomly devided into 4 groups and fed with low-fat diet(LF),high-fat diet(HF),low dose of 16:1n-7 containing high-fat diet(LPLA)and high does of 16:1n-7 containing high-fat diet(HPLA)for 8 weeks.Compared with HF,mice fed with HPLA showed significantly decreased weight gain,epididymal fat index and cell cize(P<0.05).Besides,compared with HF group,mice fed with HPLA showed decreased gene expression of IRS-1 and GLUT-4 and increased gene expression of leptin and resistin in epididymal fat(P<0.05),indicating that 16:1n-7 might play beneficial roles on the prevention of insulin resistence.(5)In rat model,8 male Wistar-Kyoto rats aged 6 weeks were used as normotensive controls,24 male spontaneously hypertensive rats(SHR)aged 6 weeks were randomly devided into 4 groups and supplemented with olive oil(OA),fish oil(FO)and sea buckthorn pulp oil rich in 16:1n-7(PLA)for 8 weeks.Compared with OA,SHR supplemented with PLA showed significantly decreased systolic blood pressure and aortic hypertrophy index(P<0.05).Besides,compared with OA,SHR supplemented with PLA showed significantly decreased gene expression of TL1R,TNFR and MyD88 in NF-?B pathway and decreased levels of IL-6,MCP-1 and ICAM-1 in aortic tissue,which might eventually prevent the development of atheroslersis.In conclusion,the present study suggested that circulating 16:1n-7 was inversely associated with obesity and hypertension in Chinese children and adolescents,age and sex could be the confounding factors.The 16:1n-7 could prevent insulin resistence in mice,suppress NF-?B pathway related gene expression and decrease aortic levels of atheroslersis-related cytokines such as IL-6,MCP-1 and ICAM-1.