Quaternary naltrexone reverses morphine-induced behaviors.
This study explored the relative role of the peripheral and central nervous systems (CNS) in the production of morphine-induced behavioral changes. Toward this end we used a quaternary derivative of an opiate antagonist (naltrexone methobromide, NM) that presumably does not cross the blood-brain barrier. Naltrexone methobromide (20, 40 and 80 mg/kg, IP) was used to challenge the stereotypic locomotion, analgesia and elevated "Straub" tail response observed in C57BL/6J mice after a 30-mg/kg (IP) injection of morphine. The quaternary derivative of naltrexone reversed the locomotor hyperactivity, "Straub" tail and analgesia normally observed in the opiate-treated C57BL/6J mouse. The data reported here, if taken at face value, suggest an important role for peripheral opiate receptors in morphine-induced behavioral changes. However, these conclusions are contingent on further research to more fully evaluate NM's capacity to cross the blood-brain barrier of the C57BL/6J mouse.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D008124:Locomotion / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds
D000644:Quaternary Ammonium Compounds; C032257:methylnaltrexone; D009271:Naltrexone; D009020:Morphine