自从发现脑内有高浓度的P物质(简称SP)以后

对SP的中枢效应进行了许多研究。由于SP在脊髓背根中浓度特别高

因此被认为是一种感觉神经元的递质。1976年Stewart等将低剂量的SP由脑内(2毫微克/只小鼠)或腹腔(5毫微克/只小鼠)注入小鼠能产生明显的镇痛效应

并能被纳洛酮(Naloxone)所逆转。此后The analgesic effect of the synthetic substance P was reinvestigated in mice. The result indicates that the peptide did not produce any detectable analgesic effect in mice. No differences were found in intraventricular or intraperitoneal administrations; the same is true for a wide range of dosages (2 ng

5 ng

50ng

2μg/mouse for intraventricular route and 10μg/mouse for intraperitoneal route). The present finding does not support the conclusion reported by many other investigators.