Mechanism Of Sesamin Improve Nitric Oxide Bioactivity In Aortas Of Spontaneously Hypertensive Rats

Objective: To explore the underlying mechanisms involved in the effect of sesamin on aortic nitric oxide bioactivity in spontaneously hypertensive rats.Methods: 40 SHRs were randomly divided into sesamin group(160mg/kg/d, n=10), sesamin group(80mg/kg/d, n=10), captopril group(30mg/kg/d, n=10) and SHR group(0.5% sodium carboxymethyl cellulose 5ml/kg/d, n=10), other normal control WKY group(0.5% sodium carboxymethyl cellulose 5ml/kg/d, n=10). All groups were gavage with these dosages in 17:00 daily for 12 weeks. The systolic blood pressure, diastolic blood pressure and mean arterial pressure was measured in conscious rats using the tail-cuff method before administration and after every 2 weeks respectively. At the end of the study, preparation of isolated aortic rings used for vascular reactivity experiments.The relaxation responses induced by acetylcholine(Ach) and sodium nitroprusside(SNP) were measured, and to observe incubation with mercaptopropionylglycine(MPG) induced by Ach aortic relaxation response. The pathologic changes of aorta were observed by HE staining. The aortic superoxide anion(O2-) levels were observed by immunofluorescence staining in situ. Catalase(CAT), total glutathione peroxidase(T-GPx) and total superoxide dismutase(T-SOD) vitality were measured by colorimetric analysis in aorta homogenates.Contents of aortic nitrotyrosine(NT) and asymmetric dimethyl arginine(ADMA) were measured by ELISA.The expression of aortic e NOS positive protein particles were observed by immunohistochemical method.The expression of aortic Caveolin-1, DHFR, p47 phox, Cu/Zn-SOD, e NOS, Phospho-e NOS and e NOS dimer/monomer protein were measured by Western Blot.Results:(1) Compared with WKY group, SBP、DBP and MAP of SHR group were significantly increased(P<0.05 or P<0.01), compared with the SHR group, sesamin groups and captopril group SBP 、 DBP and MAP decreased significantly with prolonged administration(P<0.05 or P<0.01), sesamin groups to stabilize after 10 weeks, captopril group reaching a stable level after eight weeks.(2)(1) Compared with WKY group, the aortic endothelial-dependent relaxation induced by ACh was obviously reduced in SHR group(P<0.01); compared with SHR group, the aortic endothelial-dependent relaxation induced by ACh was obviously ameliorated in sesamin and captopril groups(P<0.05 or P<0.01). Moreover, no differences were observed in the endothelium-independent vasorelaxation induced by NO donor SNP among all experimental groups. Sesamin did not modify the relaxant responses to SNP.(2) Compared with WKY group, the aortic NO oxidative inactivation was( reflected by the disparity between ACh-induced maximum relaxation values obtained in the absence and presence of MPG) significantly enhanced in SHR group; compared with SHR group, the aortic NO oxidative inactivation was significantly declined in sesamin(160mg/kg) and captopril groups.(3) Compared with WKY group, the aortic superoxide anion fluorescence increased significantly in SHR group(P<0.01); compared with SHR group, the aortic superoxide anion fluorescence intensity was significantly decreased in sesamin and captopril groups(P<0.05 or P<0.01).(4) Compared with WKY group, the aortic T-SOD activity was obviously enhanced in SHR group(P<0.01); compared with the SHR group, the aortic T-SOD activity was obviously reduced in sesamin and captopril groups(P<0.05 or P<0.01). Moreover, no differences were observed in aortic CAT and T-GPx activity among all experimental groups.(5) Compared with WKY group, the aortic NT and ADMA significantly increased in SHR group(P<0.01); compared with SHR group, the aortic NT and ADMA have different degrees lower in sesamin and captopril groups(P<0.05 or P<0.01).(6) Compared with WKY group, the aortic intima injury and smooth muscle cell hypertrophy of SHR in HE staining, but sesamin and captopril groups have different degrees of improvement.(7) Compared with WKY group, the aortic Caveolin-1、p47phox and Cu/Zn-SOD protein expression was significantly enhanced in SHR group,(P< 0.05 or P<0.01), while the DHFR protein expression decreased significantly in SHR group(P<0.01); compared with the SHR group, the aortic p47 phox and Cu/Zn-SOD protein expression have different degrees lower(P<0.05 or P<0.01), the DHFR protein expression obviously increased(P<0.05), while Caveolin-1 protein expression has not changed in sesamin and captopril groups.(8) Compared with WKY group, the aortic e NOS positive protein particles and protein expression was significantly increased in SHR group(P<0.01).The aortic Phospho-e NOS and e NOS dimer/monomer protein expression was significantly decreased in SHR group(P<0.01); compared with the SHR group, the aortic Phospho-e NOS and e NOS dimer/monomer protein expression have different degrees enhanced in sesamin and captopril groups.(P<0.05 or P<0.01), while aortic e NOS positive protein particles and protein expression has not significantly changed in sesamin and captopril groups.Conclusions:(1) Sesamin could effectively reduce SHR blood pressure, improve aortic pathological damage and enhanced aortic endothelium-dependent relaxation capacity.(2) Sesamin could reduce hypertension and improve endothelial dysfunction through enhancement of NO bioactivity in SHRs aortas. The mechanism may be elevated NO biosynthesis by upregulation of phosphorylated e NOS and suppression of e NOS dimer disruption; and reduced NO oxidative inactivation through downregulation of p47 phox and amelioration of e NOS uncoupling to reduce the generation of superoxide anion.