Effects of sodium hyaluronate on the nociceptive response of rats with experimentally induced arthritis

Abstract

Antinociceptive effects of sodium hyaluronate (Na-HA) were studied on the basis of improvement in the graded abnormal gait elicited by arthritis induced by intra-articular administration of monosodium urate crystal (MSU) to rats. One hour before MSU injection, intra-articular administration of a 1.0% solution of Na-HA with different molecular weights, ranging from 4.70×10⁵ to 2.02×10⁶ (HA-200), improved the score of abnormal gait in a molecular weight-dependent manner in the experimental arthritis model. Similarly, administrations of HA-200 at concentrations ranging from 0.1 to 1.0 % prior to MSU treatment resulted in improvement of the score in abnormal gait in a dose-dependent manner. To elucidate the antinociceptive mechanisms of Na-HA, effects of pretreatment with Na-HA (1.0%) of different molecular weights on prostaglandin E₂ (PGE₂) and bradykinin (BK) releases in synovial fluid 3 hr after MSU injection were studied. Increases in PGE₂ and BK concentration in the synovial fluid were depressed in a molecular weight-dependent manner by Na-HA (1.0 %) pretreatment. These results indicate that Na-HA attenuates the nociceptive responses inflicted by the MSU-induced arthritis. Such an antinociceptive effect may be due to the inhibition of PGE₂ and BK synthesis in the synovial joint of rats.