Tolerance to the anticonvulsant effect of morphine in mice: blockage by ultra-low dose naltrexone.
The present study evaluated the development of tolerance to the anticonvulsant effect of morphine in a mouse model of clonic seizures induced by pentylenetetrazole, and whether ultra-low doses of the opioid receptor antagonist naltrexone which selectively block G(s) opioid receptors were capable of preventing the observed tolerance. The results showed that the morphine anticonvulsant effect could be subject to tolerance after repeated administration. Both the development and expression of tolerance were inhibited by ultra-low doses of naltrexone, suggesting the possible involvement of G(s)-coupled opioid receptors in the development of tolerance to the anticonvulsant effect of morphine.
Roshanpour
Maryam
M
Department of Pharmacology, School of Pharmacy, Medical Sciences/University of Tehran, Tehran, Iran.
Ghasemi
Mehdi
M
Riazi
Kiarash
K
Rafiei-Tabatabaei
Neda
N
Ghahremani
Mohammad Hossein
MH
Dehpour
Ahmad Reza
AR
D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000704:Analysis of Variance; D000818:Animals; D000927:Anticonvulsants / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004361:Drug Tolerance / Q000502:physiology; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage*; D009271:Naltrexone / Q000627:therapeutic use*; D009292:Narcotic Antagonists / Q000627:therapeutic use*; D010433:Pentylenetetrazole; D012640:Seizures / Q000139:chemically induced / Q000188:drug therapy*
D000701:Analgesics, Opioid; D000927:Anticonvulsants; D009292:Narcotic Antagonists; D009271:Naltrexone; D009020:Morphine; D010433:Pentylenetetrazole