Bacitracin produces analgesia by increasing brain immunoreactive beta-endorphin (beta-E) content.
The effects of protease inhibitor bacitracin on brain beta-endorphin content and analgesia, were examined in vivo. Male Sprague-Dawley rats were injected with bacitracin intracerebroventricularly and sacrificed by microwave irradiation 15 and 30 min after injection. Brain beta-endorphin levels were 27% higher in bacitracin treated rats than in controls. A second group of bacitracin injected rats was subjected to continuous intermittent 55 degrees C hot plate exposure. Bacitracin-injected rats exhibited total analgesia 15 min after bacitracin injection. At 30 min, this analgesic effect subsided. Control rats exhibited no analgesia. Bacitracin induced analgesia was naloxone reversible at a low dose of naloxone (1 mg/kg). At a higher dose of naloxone (10mg/kg), bacitracin induced analgesia was only partially antagonized. These results suggest that bacitracin induced analgesia might be due to the elevated levels of brain beta-endorphin caused by a decrease in its breakdown by bacitracin.
D000700:Analgesics; D000818:Animals; D001414:Bacitracin / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001923:Brain Chemistry / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D000700:Analgesics; D001414:Bacitracin; D009270:Naloxone