Therapeutic effect of Captopril on rheumatoid arthritis in rats

To investigate the therapeutic effect of the intervention treatment with different doses of Captopril on TNF-αcontents in serum of rheumatoid arthritis (RA) rats, and to provide the theoretical proofs for clinical application of Captopril in treatments of rheumatoid diseases.

Fifty Wistar rats were randomly divided into 5 groups, namely, Group A, Group B, Group C, Group D, Group E with 10 rats in each group. Injection of Freund's complete adjuvant was employed to establish adjuvant-induced arthritis model in rats. Group A was model group; after model establishment, rats were treated with 20 mL normal saline as placebo (ip.). Rats in Group B were treated with 8 mg/kg cyclophosphamide (ip.). Rats in Group C, D and E were intraperitoneally injected with 30 mg/kg, 100 mg/kg and 300 mg/kg Captopril respectively. Rats in each group were subjected to continuous treatment for 3 weeks, and then sacrificed. Eyeballs of rats were excised and blood was collected. TNF-αcontent in serum were detected using ELISA; each group rats were compared for the hind legs arthrocele. Right ankle tissues of rats were collected to prepare section, and microscopic observation of pathological changes was performed.

TNF-αcontent in serum of Group A rats was significantly higher than that of rats in other 4 groups (P<0.05). TNF-αcontent in serum of Group B rats was significantly lower compared with that of rats in Groups C, D and E. The highest TNF-αcontent in serum of rats treated with Captopril was found in Group C, followed by Groups D and E (P<0.05). Right ankle arthrocele of rats in Groups B, C, D and E in early stage showed no statistical difference compared with that of Group A rats (P>0.05). From Day 8, ankle arthrocele of rats in Groups B, C, D and E was obviously relieved compared with that of Group A rats; the anti-inflammatory effects were gradually enhanced with the extension of medication time. Treatments of Groups C, D and E showed significant activities against tardive arthrocele; the degree of ankle arthrocele in rats of these three groups was lower than that of Group A rats (P<0.01). Histological observation showed that large amount of inflammatory cells and plasmocyte infiltration was found in ankle synovial tissues of Group A rats. Relief of hyperaemia and edema of right ankle synovial tissues as well as significant decrease in synoviocyte layer hyperplasia, intra-articular inflammatory cells infiltration and cartilago articularis damage degree etc. were observed in Groups B, C, D and E.

Intervention treatment with Captopril can effectively reduce the TNF-αcontent in serum of rheumatoid arthritis rats and inhibit the generation of inflammatory factors, so as to achieve the therapeutic effect.