Elucidation of the mechanism underlying the suppression of the development of analgesic tolerance to morphine under chronic pain

本研究探讨了慢性疼痛条件下吗啡镇痛耐受抑制的机制。足底注射1%福尔马林可明显抑制小鼠对吗啡的镇痛耐受。由福尔马林引起的吗啡镇痛耐受抑制可被一氧化氮前体L精氨酸显著逆转，但不能被D-精氨酸逆转。这些结果提示，在福尔马林诱导的疼痛中，抑制吗啡的镇痛耐受可能是通过抑制一氧化氮的产生来实现的。

This study examined the mechanism underlying suppression of analgesic tolerance to morphine under chronic pain condition. Chronic pain was induced by intraplantar injection of 1% formalin, which significantly suppressed the development of analgesic tolerance to morphine. The formalin-induced suppression of analgesic tolerance to morphine was significantly reversed by L-arginine, a precursor of nitric oxide, but not by D-arginine. These results suggest that suppression of analgesic tolerance to morphine under formalin-induced pain may be mediated through the inhibition of nitric oxide production.