Release of inflammatory mediators by noxious stimuli; effect of neurotropin on the release.

Anesthetized rats were perfused with saline in the subcutaneous space of the hind paw and the release of inflammatory mediators induced by noxious stimuli was studied. Not only immunoreactive bradykinin (BK) but also histamine, serotonin (5-HT) and immunoreactive prostaglandin E2 (PGE2) were found to be released into the perfusate when the paw was pinched. Neurotropin, used clinically as an analgesic and anti-allergic drug in Japan, inhibited the release of BK in dose-dependent manner without altering the release of histamine, 5-HT and PGE2. The maximal inhibition of BK release was observed 60 min after p.o. administration of neurotropin. Indomethacin failed to inhibit the release of BK.