COMBINED TREATMENT WITH REN-SHEN-YANG-RONG-TANG (JAPANESE NAME- NINJIN-YOUEI-TO) PLUS PREDNISOLONE ON ADJUVANT-INDUCED ARTHRITIS IN LEWIS RAT

The effects of combined treatment with 250 mg/kg Ren-shen-yang-rong-ta ng (Japanese name: Ninjin-youei-to, NYT) plus 4 mg/kg, an average dosa ge, or 0.2 mg/kg, a suboptimal dosage, of prednisolone (PSL) on adjuva nt-induced arthritis in Lewis rats were investigated using two treatme nt schedules. The agents were administered orally every day from day 0 to 21 (schedule A), or from day -7 to 21 (schedule B) after adjuvant injection. PSL treatment (4 mg/kg) obviously inhibited paw swelling du e to non-immune inflammation, diminished the weights of the thymus, sp leen, adrenals and iliac lymph nodes, and suppressed the increment of serum interleukin (IL)-6 concentration in both schedules compared to c ontrols. NYT treatment alone inhibited paw swelling due to immune infl ammation, diminished the weight of the adrenals and decreased IL-6 con centration only in schedule A. Combined treatment with NYT plus PSL (4 mg/kg) showed: (1) a superior effect to that of PSL on paw swelling i n the uninjected hind foot, especially in schedule B, (2) a tendency t o diminish adrenal weight in schedule A and the weights of all four or gans in schedule B compared with PSL treatment alone, and (3) a suppre ssive effect on IL-6 concentration weaker than that of PSL alone in sc hedule B. The suppressive effect of combined treatment with NYT plus P SL (0.2 mg/kg) on paw swelling was significantly stronger compared wit h either NYT or PSL treatment alone in schedule B. Although this dose of PSL had no influence upon the IL-6 concentration, the combined trea tment or NYT alone increased the IL-6 concentration. Mechanisms underl ying the synergistic suppressive effects on paw swelling are discussed .