Effects Of Whey Protein Supplementation And Treadmill Running On The Blood Pressure In Spontaneously Hypertensive Rats

Hypertension is a major public health problem wordwide,usually associated with such other disorders as obesity,prediabetes,renal disease and atherosclerosis.It remains a major risk factor for cardiovascular diseases(CVD)and heart stroke.Healthy diet and moderate exercise has been largely recognized as an efficient strategy in the management of hypertension.In recent years,the role of whey protein and exercise has created considerable attention in hypertension,it is important to further explore effective non-pharmacologic strategies for hypertension as well as the potential underlying mechanisms.Objective:We aimed to explore the effects of treadmill running combined with whey protein supplementation on the blood pressure in spontaneously hypertensive rats(SHR)and the potential underlying mechanisms.On the other hand,we performed meta-analysis to investigate the effect of whey protein intake on inflammatory marker,C-reactive protein(CRP),one of risk factors for CVD.Methods:1.Effects of whey protein supplementation and treadmill running in SHRs:sixty-6-wk-old male SHRs were randomized into 5 groups:CON(control group),10%WHEY(10%whey protein),20%WHEY(20%whey protein),TE(trained on a treadmill)and TW(10%whey protein combined with TE)groups.During the intervention,rats were weighed weekly.Food intake was recorded every two weeks.Meanwhile,we measured the serum ACE activity every 4 weeks.Furthermore,systolic blood pressure(SBP),diastolic blood pressure(DBP),mean blood pressure(MBP)and heart rats(HR)were measured in conscious rats using a tail-cuff plethysmograph every 4 weeks.The experiment lasted for 24 weeks and animals were sacrificed for the following determinations:(1)Basic index:At the end of the experiment,the kidney index,cardiac index and liver index of SHRs were calculated.(2)Lipid metabolism:we examined the serum triglyceride(TG),total cholesterol(TC),glycerol and non-esterified fatty acid(NEFA)and glycerol level.The lipolysis related protein including p-hormone-sensitive lipase 660(p-HSL660),p-Adenosine5‘-monophosphate(AMP)-activated protein kinase(p-AMPK)and adipose triglyceride lipase(ATGL)were measured by Western blotting.(3)Inflammatory system:we examined the serum C-reactive protein(CRP),interleukin-1?(IL-1?)and tumor necrosis factor-alpha(TNF-?)level.The inflammation related protein including PPAR-?and TNF-?were measured by Western blotting.(4)Blood pressure system:We observed the serum angiotensin-converting enzyme(ACE),nitric oxide(NO)and endothelin-1(ET-1)level.Protein expression of RhoA,ROCK1 and p-MLC2 in thoracic aorta were measured by Western blotting.2.Meta-analysis:We conducted a systematic literature search of PubMed,the Web of Science and the Cochrane library through July,2014,using the following search terms:“whey OR dairy OR milk”in combination with“inflammatory OR C-reactive protein OR CRP”.A meta-analysis was performed with heterogeneity analysis,subgroup analysis,sensitivity analysis and potential publication bias using STATA version 12.0.Results:Effects of whey protein supplementation and treadmill running in SHRs:(1)Basic index:body weight and food intake were similar among the 5 groups during the experiment.The kidney index,cardiac index and liver index of TE and TW group were slightly increased compared with CON group(p>0.05),while the kidney index and liver index of 10%WHEY were slightly decreased compared with CON group(p>0.05).(2)Lipid metabolism:Serum TC levels of 20%WHEY and TE showed significant decrease compared with CON group(p<0.05),and the NEFA and glycerol levels of TW were significantly decreased(p<0.05).There was no significant difference in serum TG among the 5 groups.The expression of the lipolysis related protein including p-HSL660,p-AMPK and ATGL were not significantly affected by the interventions(p>0.05).(3)Inflammatory system:the CRP levels of 20%WHEY and TW were significantly decreased compared with CON group(p<0.05),while the serum IL-1?and TNF-?levels were not changed during the experiment among the 5 groups(p>0.05).20%WHEY significantly decreased the expression of TNF-?protein(p<0.05),while there was no significant change in the expression of PPAR-?protein among the 5 groups(p>0.05).(4)Blood pressure system:At the end of the intervention,only 10%whey protein treatment significantly decreased SBP,DBP and MBP compared with control.Final serum ACE levels were significantly reduced in both TE and TW group(p<0.05).For the serum NO and ET-1 levels,no significant differences were observed among the 5groups(p>0.05).The protein expression of RhoA was significantly decreased in 20%WHEY and the protein expression of ROCK1 was significantly decreased in10%WHEY,while there was no significant change in the expression of p-MLC2 protein among the 5 groups(p>0.05).2.Meta-analysis:Nine RCTs included in our meta-analysis.Considering the evidence of heterogeneity(p<0.01,I~2=87.3),we applied the random-effects model.The pooled effect of whey supplementation on circulating CRP level was-0.42 mg/L(95%CI,-0.96,0.13)compared with that of the control group.For subgroup analysis,whey supplementation produced a significantly greater CRP reduction among the trials at a whey dose?20 g/day(-0.72 mg/L,95%CI-0.97,-0.47)and with a baseline CRP?3mg/L(-0.67 mg/L,95%CI-1.21,-0.14).Conclusions:1.During the experiment,10%whey protein significantly decreased the blood pressure.There were no effects of treadmill running and the combination on the antihypertensive effects in SHR after 24 weeks of treatment.However,we observed significant reduction in circulating ACE activity in SHR with the treadmill running and the combination with the 10%whey protein.Treadmill running combined with whey protein supplementation could not improve endothelial function;however it can improve the serum lipids and inflammatory response.Thus,dosage of whey protein and type and intensity of exercise training should be further investigate in established hypertension rats.2.Our Meta-analysis did not support the overall favorable effect of whey protein on circulating CRP level,based on the current evidence.However,the supplementation of whey protein and its derivates may produce a significant reduction in CRP among participants supplemented with a high dose of whey proteins or increased baseline CRP level.