Anti-hypertensive Mechanism of the Enzymatic Hydrolysate of Lycium barbarum Protein on Spontaneously Hypertensive Rats

Objective:The paper was to explore the effects of enzymatic hydrolysate of Lycium barbarum protein on the renin-angiotensin system(RAS)in spontaneously hypertensive rat(SHR)and its possible antihypertensive mechanism. Methods:SPF wistar rat inbred line male SHR were respectively given saline solution,10 mg/kg of captopril,low-dose group of enzymatic hydrolysate of Lycium barbarum protein(40 mg/kg),middle-dose group(80 mg/kg),and high-dose group(100 mg/kg)by gavage. Wistar-kyoto(normal rats,WKY)served as normal control group were given saline solution by gavage for 9 consecutive weeks. The contents of plasma angiotensin Ⅱ(AngⅡ)was detected by enzyme-linked immunosorbent assay,the mRNA expression levels of angiotensin-converting enzyme(ACE),AngⅡ type 1 receptor(AT1-R),angiotensin-converting enzyme 2(ACE2)and mas receptor(Mas-R)in heart and kidney tissues were analyzed by RT-qPCR(real-time fluorescent quantitative polymerase chain reaction)method. Results:Compared with WKY,the food intake of SHR increased significantly and the body weight was significantly lower than WKY group(p<0.05),the systolic blood pressure(SBP)and diastolic blood pressure(DBP)of SHR were significantly increased(p<0.05). The contents of AngⅡ in plasma were obviously increased. The expression of ACE and AT1-R mRNA were up-regulated,while ACE2 and Mas-R mRNA were down-regulated. Compared with saline-treated SHR,the weight of captopril-treated group decreased significantly(p<0.05),the SBP of captopril-treated group,low-dose,middle-dose,and high-dose group were significantly decreased(p<0.05). Among them,the low-dose group of enzymatic hydrolysate of Lycium barbarum protein could significantly decrease the contents of AngⅡ in plasma of SHR(p<0.05),down-regulation of the expression of ACE mRNA(p<0.05)in heart and kidney tissues,and up-regulation of the expression of ACE2 mRNA(p<0.05). Conclusion:The enzymatic hydrolysate of Lycium barbarum protein could effectively decrease the blood pressure of SHR. The mechanism might be through inhibiting the activity of ACE,down-regulation of the expression of ACE,AngⅡ and AT1-R mRNA and up-regulation of expression of ACE2 and mas-R mRNA to achieve anti-hypertensive effect.