OBJECTIVETo study the effect of geniposide-acid(GA) on the anti-inflammatory action for adjuvant-induced arthritis (AA) rats and the proliferation of synoviocytes in AA rats and the feasible mechanism of apoptosis in vitro.

METHODForty-eight health male Wistar rats were divided randomly into six groups and were administered respectively with 200, 100, 50 mg x kg(-1) GA and 0.75 mg x kg(-1) MTX and normal sodium (normal or model control group) for four weeks when right posterior paw pads of rats excluding normal control group were injected intrademally with complete Freund's adjuvant after 19 days. The left posterior paws swelling degree, swelling inhibition ratio and arthritis index of secondary inflamation were detected. The TNF-alpha and IL-1beta proteins in serum of rats were assayed by enzyme linked immunosorbent assay (ELISA) kits. The synovial fibroblasts of AA rats were exposed to 1-4 micromol x L(-1) GA or 4 micromol x L(-1) MTX. The effect of GA on the proliferation of synoviocytes was detected by MTT assay. The morphologic change of apoptosis cells was observed by Hoechst/PI double stainning and fluorescence microscope. The rate of apoptosis cells was analyzed by flow cytometry. The mRNA expresstion of Bcl-2 and Bax gene was detected by reverse transcription PCR (RT-PCR).

RESULT200 mg kg(-1) or 100 mg kg(-1) GA could decrease significantly the paw swelling degree, arthritis index and the level of TNF-alpha and IL-1beta proteins in serum of AA rats (P < 0.05 or P < 0.01) with 25.4%, 21.37% of the swelling inhibition ratio respectivly, 34.61%, 28% of protein inhibition ratio of TNF-alpha and 29.05%, 21.65% of that of IL-1beta. GA(1-4 micromol x L(-1)) inhibitated significantly the proliferation of synoviocytes culcured for 5 days. Flow cytometry showed that 1, 2, 4 micromol x L(-1) GA increased obviously the rate of apoptosis cells, the apoptosis ratios were 15.8%, 24.3%, 40.7% respectivly (P < 0.01). RT-PCR showed GA could decrease the expression level of Bcl-2 gene but increase that of Bax gene (P < 0.05 or P < 0.01).

CONCLUSIONGA could inhibit the secondary inflamation of AA rats and decrease the level of TNF-alpha and IL-1beta protein in the AA rats serum. GA could inhibit the proliferation of AA rat synoviocytes in vitro and induce apoptosis which mechanism was concerned with down-regulating the mRNA expression of Bcl-2 and up-regulating that of Bax.