Effect of mild moxibustion on vascular aging in senescence rats based on local MCP-1/MMP-2/TGF-β1 pro-inflammatory signal loop

Abstract

To observe the effect of mild moxibustion on monocyte chemotaxis protein 1 (MCP-1)/matrix metalloproteinase 2 (MMP-2)/transforming growth factor β1 (TGF-β1) pro-inflammatory signal loop in senile rats, so as to explore its mechanisms underlying improving vascular aging (VA). Twenty-four male VA SD rats were randomized into senium (VA) control, medication and moxibustion groups, and other 8 young SD rats (aged 2 months) were used as the young control group. The VA model was established by intraperitoneal injection of D-galactose (300 mg·kg-1·d-1) once daily for 4 weeks, and verified by serum total testosterone (TT) and free testosterone (FT) levels. For rats of the moxibustion group, mild moxibustion was applied to bilateral "Shenshu"(BL23) and "Guanyuan"(CV4) for 20 min, once a day, 5 days a week for 8 weeks. Rats of the medication group were treated by intraperitoneal injection of testosterone propionate (7 mg·kg-1·[3 d]-1) once daily for 8 weeks except weekends, and rats of the senium control and young control groups treated by intraperitoneal injection of the same dose of normal saline, once daily for 8 weeks except weekends. The duration of exhausted swimming (DES) before and after the treatment was recorded. H.E. staining and Masson staining were used to observe histopathological changes and collagen fiber content of the thoracic aortic tissue, respectively. The contents of serum TT, FT and angiotensin 2 (Ang Ⅱ) were determined by ELISA. The immunoactivity of aortic MCP-1 was detected by immunohistochemistry, and the expression levels of aortic MCP-1, MMP-2 and TGF-β1 were detected by Western blot. Compared with the young control group, the levels of DES, serum TT and FT contents were significantly decreased (P<0.01), while those of serum AngⅡ and collagen fiber contents, aortic MCP-1 immunoactivity and MMP-2, TGF-β1 and MCP-1 protein expression considerably increased in the senium control group (P<0.01). After the interventions, the decreased levels of DES, serum TT and FT contents and the increased levels of serum AngⅡ, collagen fiber contents, aortic MCP-1 immunoactivity and MMP-2, TGF-β1 and MCP-1 protein expression were reversed in both medication and moxibustion groups (P<0.01, P<0.05). The therapeutic effect of mild moxibustion was significantly superior to that of medication in down-regulating the aortic collagen fiber, serum AngⅡ contents and MCP-1 immunoactivity and protein expression (P<0.05). H.E. staining showed thickened endometrium and disordered arrangement of vascular smooth muscles of the aorta in the senium group, and thinner endometrium and regular and ordered arrangement of aortic vascular smooth muscles in both moxibustion and medication groups. Mild moxibustion may improve vascular aging in senescence rats, which is possibly by suppressing vascular MCP-1/MMP-2/TGF-β1 pro-inflammatory signal loop.