The role of renin-angiotensin system in compound 48/80-induced analgesia in rats

1. The antinociceptive effect of compound 48/80 was reversed by the pretreatment with an angiotensin-converting enzyme (ACE) inhibitor, Hoe 498, in a dose-dependent manner and with a opiate receptor antagonist, naloxone (5.0 mg/kg, s.c.) in rats. 2. The increase of plasma beta-endorphin-like immunoreactivity produced through s.c. administration of compound 48/80 was attenuated by the pretreatment with Hoe 498 but not with naloxone. 3. The present data suggest the possible involvement of renin-angiotensin system in compound 48/80-induced analgesia in rats.