Expression Of AT₁R, AT₂R, ACE2 In Kidney, Heart In Spontaneously Hypertensive Rats

【Objective】To investigate the expression of AT₁R,AT₂R,ACE2 protein in kidney,heart of different age spontaneously hypertensive rats(SHR)and to explore the role of these factor in the development of hypertension.【Methods】Male SHR(n=30) were allocated to five groups by age: 1)one-month-old group(S₁); 2)two-month-old group(S₂); 3)three-month-old group(S₃); 4)six-month-old group(S₆); 5)nine-month-old group(S9). Sex and age matched Wistar-Kyoto NOrmotensive rats(WKY)served as controls. Blood pressure was measured. Plasma concentration of angiotensinâ…¡(Angâ…¡)was measured by radioimmunoassay(RIA). Collagen of the heart was stained by sirus red to observe the myocardial fibrosis.The expression of AT₁R,AT₂R,ACE2 in kidney and heart was examined by immunohistochemistry and computer image analysis.【Results】1. An age-dependent increase of SBP was observed in SHR before six months(P<0.05), but there was no similar trend in WKY(P>0.05); the SBP was higher in S6 than that in S₁(P<0.05), and no difference was observed between S6 and S9(P>0.05); the SBP was higher in the different age SHR than that in the matched WKY(P<0.05).2. Plasma Angâ…¡concentration was higher in S₂, S₃, S6 and S₉ than that in S₁(P<0.05), and no difference was observed among S₂, S₃, S₆ and S₉(P>0.05); no difference was observed between the different age WKY(P>0.05); plasma Angâ…¡concentration was higher in S₂, S₃, S₆ and S₉ than that in the matched WKY(P<0.05).3. The quantification of AT₁R immunohistochemical staining showed: An age-dependent increase of the AT₁R was observed in kidney in SHR(P<0.05), The AT₁R levels were higher in SHR than those in the matched WKY(P<0.05). no difference was observed between the different age WKY(P>0.05). An age-dependent increase of the AT₁R was observed in heart in SHR(P<0.05), which reached the peak in the third month and remained stable after the sixth month. The AT₁R levels were higher in SHR than those in the matched WKY(P<0.05).4. The quantification of AT₂R immunohistochemical staining showed: An age-dependent decrease of the AT₂R was observed in kidney in SHR(P<0.05), which was lower in S6 than that in S₁(P<0.05), and no difference was observed between S6 and S(9P>0.05).The AT₂R levels were lower in SHR than those in the matched WKY(P<0.05). An age-dependent decrease of the AT₂R was observed in heart in SHR(P<0.05), which was lower in S9 than that in S₁(P<0.05), and no difference was observed between S6 and S₃(P>0.05)The AT₂R levels were lower in SHR than those in the matched WKY(P<0.05).5. The quantification of ACE2 immunohistochemical staining showed: An age-dependent increase of the ACE2 was observed in SHR and WKY(P<0.05), which reached the peak in the third month and remained stable after the sixth month. The ACE2 levels were lower in SHR than those in the matched WKY(P<0.05). Interestingly, the ACE2 stained area was higher in the inner medulla region than that in the cortex and outer medulla in one-month-old SHR and WKY (P<0.05), which was different from the distribution of other groups.6. The content of collagen in the heart of SHR showed:An age-dependent increase of the myocardial fibrosis was observed in SHR(P<0.05).【Conclusions】1. The expression of AT₁R protein in kidney,heart of SHR is increased compared with WKY. The expression of AT₂R protein in kidney,heart of SHR is decreased compared with WKY. An age-dependent varies of AT₁R, AT₂R protein was observed in SHR. The expression of ACE2 protein in kidney of SHR is decreased compared with WKY.. 2. The expression of ACE2 protein in kidney has space-time difference.