Effects of morphine on cutaneous blood flow and substance P release evoked by electric stimulation of rat sciatic nerve
Chen, J.Q.; Yonehara, N.; Imai, Y.; Xu, W.J.; Inoki, R.
Zhongguo Yao Li Xue Bao 12(4): 355-357
1991
ISSN/ISBN: 0253-9756 PMID: 1725470 Document Number: 371317
Electric stimulation of the rat sciatic nerve containing sensory afferent fibers produced an increase in cutaneous blood flow. Morphine (10, 30 .mu.mol .cntdot. kg-1 ia infusion) inhibited the electric stimulation-induced increase of the cutaneous blood flow velocity, and its effect was antagonized by naloxone (2 mg .cntdot. kg-1 ip). In order to investigate the cause of this effect, we determined immunoreactive substance P (iSP) levels in the sc perfusate of hind paw. We found that electric stimulation of the sciatic nerve led to a significant increase of iSP release into the sc perfusate. Morphine (30 .mu.mol .cntdot. kg-1 ia fusion) inhibited the electrical stimulation-induced release of iSP, and this effect was completely antagonized by naloxone (2 mg .cntdot. kg-1 ip). These results suggest that morphine-induced inhibition of the electrical stimulation-evoked increase in cutaneous blood flow could result from inhibition of the release of SP from peripheral sensory nerve endings.