Oxymatrine-carbenoxolone sodium inclusion compound induces antinociception and increases the expression of GABA(A)alpha1 receptors in mice

Oxymatrine-carbenoxolone sodium inclusion compound (OCSIC) has been reported as a novel painkiller, but its effectiveness and mechanism remain unknown. This study investigated the analgesic effects of OCSIC and the possible alterations in the expression of gamma-aminobutyric acid type A alpha1 (GABA(A)alpha1) receptors in the central nervous system caused by the compound. The antinociceptive action of the OCSIC was assessed in thermal and chemical behavioral models of nociception. The hot-plate test, tail immersion test, acetic acid-induced abdominal constriction and formalin-induced pain were used in ICR mice. OCSIC was administered intraperitoneally (i.p.) or intracerebroventricularly (i.c.v.). In all cases, OCSIC produced significant dose-dependent antinociceptive effects. In addition, OCSIC (150 mg/kg) increased the expression of positive staining cells of GABA(A)alpha1 receptors. These results reveal that the antinociceptive effects of OCSIC may be involved in the central nervous system and the peripheral nervous system. The involvement of GABA(A) receptors in the antinociceptive effect of OCSIC is now under investigation.