Achyranthis bidentatae radix enhanced articular distribution and anti-inflammatory effect of berberine in Sanmiao Wan using an acute gouty arthritis rat model.

ETHNOPHARMACOLOGICAL RELEVANCE: Sanmiao Wan (SMW) has been a basic prescription employed for the treatment for gout in the clinic since Yuan dynasty. Achyranthis bidentatae radix (ABR) is designed as a lower-guiding drug in SMW to augment the articular accumulation of active ingredients and improve the anti-inflammatory effect.

AIM OF THE STUDY: Present study was undertaken to investigate the dose-response relationship of berberine in SMW between the articular concentration and anti-inflammatory effect in the knee joint under the lower-guiding of ABR.

MATERIALS AND METHODS: Rats were divided into control group, model group and SMW without or with low, medium and high doses of ABR groups. Rat model of acute gouty arthritis (AGA) was established by intra-articular injection of 0.2 mL monosodium urate crystal (20 mg/mL) inside knee joint cavity on day 2 during drug treatment slots. Knee joint swelling, synovial hyperplasia and inflammatory cell infiltration were investigated for anti-inflammatory study. The concentrations of berberine in rat plasma and tissues were determined by UPLC-MS/MS method. The effect of ABR on the expression levels of P-glycoprotein (P-gp) and MDR1 mRNA in the synovial tissues of knee joints in AGA rats was examined by Western blot and RT-qPCR assay, respectively.

RESULTS: The distribution of berberine increased by 6.53%, 44.31% and 212.96% in the knee joint and 474.93%, 631.01% and 1063.3% in the ankle for SMW with low, medium and high doses of ABR groups, compared with SMW without ABR group. Similarly, the plasma level of berberine increased by 19.81%, 143.4% and 681.13%. On the contrary, the distribution of berberine evidently decreased 3.23, 10.61 and 46.21-fold in heart and 3.68, 6.74 and 24.78-fold in lung. SMW with different doses of ABR groups exhibited better efficiency than SMW without ABR group on ameliorating knee joint swelling, inhibiting synovial hyperplasia and alleviating inflammatory cell infiltration of AGA rats. The treatment with ABR could down-regulate the MDR1 mRNA and P-gp expressions of synovial tissues of knee joints in AGA rats.

CONCLUSIONS: The enhanced articular distribution of berberine in SMW was attributed to the lower-guiding effect of ABR, which could evidently increase the plasma concentration of berberine, improve the supply of blood of inflamed joint, reduce the distribution of berberine in heart and lung and significantly inhibit the MDR1 mRNA and P-gp expression of synovial tissues of knee joints in AGA rats. The dose-response relationship of berberine between the enhanced articular concentration and improved anti-inflammatory effect in the knee joint under the lower-guiding of ABR was observed for the first time.