Are anti-inflammatory properties of lipoic acid associated with the formation of hydrogen sulfide?

BACKGROUND Lipoic acid (LA) was shown to possess anti-inflammatory properties. In this study, we present evidence supporting the hypothesis that the anti-inflammatory properties of LA are associated with the formation of hydrogen sulfide (H2S). METHODS The study was conducted on male albino Swiss mice. The animals were treated with carrageenan by subcutaneous (sc) injection into the right hind paw to induce acute inflammation. Animals were treated intraperitoneally (ip) with LA (30, 50 and 100 mg/kg) or indomethacin (20 mg/kg) 30 min before carrageenan administration. The control group was given ip the vehicle (1% Tween 80) 30 min before carrageenan administration. Additional experiment involved ip combined treatment of mice with glibenclamide (10 mg/kg) or glibenclamide (10 mg/kg) and LA(100 mg/kg) 30 min before carrageenan administration. LA, indomethacin and glibenclamide were suspended in 1% Tween 80. At 1, 2 and 3 h after treatment with carrageenan the degree of the paw edema was evaluated by the measurement of the paw volume using aqueous plethysmometer. RESULTS Injection of carrageenan into the mouse hind paw increased paw volume. The increase in paw edema was completely suppressed by pretreatment with LA. The reduction of paw edema by LA was abolished by pretreatment with the K(ATP) channel antagonist, glibenclamide. CONCLUSION Our findings demonstrate for the first time in vivo that the anti-inflammatory activity of LA might be connected with the formation of H2S.