Study On Effect And Mechanism Of Proanthocyanidins From Grape Seeds On Treatment Of Recurrent Ulcerative Colitis In Rats

Aim:The aim of the present study was to investigate the therapeutic effect and mechanism of proanthocyanidins from grape seeds (GSPE) in the treatment of recurrent ulcerative colitis (UC) in rats.Methods:Rats were randomized into six groups:normal control group, acute colitis group, spontaneous healing colitis group, recurrent colitis model control group, SASP group and GSPE group. To induce recurrent colitis, rats were instilled with 2,4, 6-trinitrobenzenesulfonic acid (TNBS) (80 mg/kg) into the colon through the cannula in the first induced phase, and then the rats were second instilled with TNBS (30 mg/kg) into the colon on the 16th day after the first induction UC. Rats were intragastrically administered GSPE (200 mg/kg) per day for 7 days after twice-induction of colitis by TNBS. Sulfasalazine (SASP) at 500 mg/kg was used as a positive control drug. Rats were killed 7 days after GSPE treatment. The colonic injury and inflammation were assessed by macroscopic and macroscopic damage scores, colon weight/length ratio (mg/cm) and myeloperoxidase (MPO) activity. Then, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), inducible nitric oxide synthase (iNOS) activities, and the levels of malonyldialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) in serum and colonic tissues were measured.Results:Compared with recurrent UC group, GSPE treatment facilitated recovery of pathologic changes in the colon after induction of recurrent colitis, as demonstrated by reduced colonic weight/length ratio and macroscopic and microscopic damage scores (P<0.05 or P<0.01). The MPO and iNOS activities with MDA and NO levels in serum and colon tissues of colitis rats were significantly decreased in GSPE group compared with the recurrent UC group (P<0.05 or P<0.01). In addition, GSPE treatment was associated with notably increased SOD, GSH-Px activities and GSH levels of colon tissues and serum of rats. No statistical difference was observed in any biochemical analysis between the SASP and GSPE treatment group, except for the MPO activity in serum of the GSPE group that were significantly lower than the SASP group.Conlusions:GSPE exerted a protective effect on recurrent colitis in rats by modifying the inflammatory response, inhibiting inflammatory cell infiltration and antioxidation damage, promoting damaged tissue repair to improve colonic oxidative stress, and inhibiting of colonic iNOS activity to reduce the production of NO.Aim:To elucidate the molecular mechanisms involved in the therapeutic effects of proanthocyanidins from grape seeds (GSPE), we explore whether GSPE regulates the inflammatory response of 2,4,6-trinitrobenzenesulfonic acid (TNBS) induced recurrent colitis in rats at the levels of MAPK and NF-κB signal transduction pathways.Method:Rats were intragastrically administered different doses of GSPE (100,200, and 400 mg/kg) per day for 7 days after recurrent colitis was twice-induced by intracolonic injection of TNBS dissolved in 50% ethanol. Sulfasalazine (SASP) at 500 mg/kg was used as a positive control drug. The inflammatory response was assessed by gross appearance, myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities, malonyldialdehyde (MDA) and nitric oxide (NO) levels and a histological study of the lesions. We determined GSH production as well as the GSH-Px and SOD activities by biochemical methods. The expression levels of extracellular signal regulated kinase (ERK), c-Jun NH2-terminal terminal kinase (JNK), p38 mitogen-activated protein kinase (p38MAPK), c-Jun and c-Fos, nuclear transcription factor activator protein-1 (AP-1) and nuclear factor-kappa B (NF-κB) in the colon tissues were all measured by enzyme-linked immunosorbent assay (ELISA) methods.Result:GSPE treatment was associated with a remarkable amelioration in macroscopic and microscopic colitis scores, decreased colonic and serum MPO and iNOS activity as well as MDA and NO levels in TNBS-induced recurrent colitis. The GSH-Px, SOD activity and GSH levels in colonic and serum of rats treated with GSPE were significantly increased as compared to recurrent control group. GSPE reduced the expression levels of ERK, JNK, p38MAPK, c-Jun, c-Fos, AP-1, and NF-κB in the colon mucosa.Conclusion:(1) GSPE showed significantly dose-dependent effects on some indices of TNBS-induced recurrent colitis in rats, such as MPO and GSH-Px activity, NO and GSH levels in colonic tissues. GSPE did not show dose-dependent effects, however, on colonic MDA levels, weight/length ratio, macroscopic damage scores, macroscopic damage scores, and serum GSH-Px activity et al. It may by that the low or medium dose of GSPE already shows maximal therapeutic effect. (2) GSPE exerted a protective effect on recurrent colitis in rats by inhibition of MAPKs and NF-κB signal transduction pathways, modificating the inflammatory response and promoting damaged tissue repair to improve colonic oxidative stress.