title: Acute and chronic fentanyl administration causes hyperalgesia independently of opioid receptor activity in mice.
abstract: Although mu-receptor opioids are clinically important analgesics, they can also paradoxically cause hyperalgesia independently of opioid receptor activity, presumably via the action of neuroexcitatory glucoronide metabolites. However, it is unknown whether the commonly used mu-receptor opioid analgesic fentanyl, which is not subject to glucuronidation, can also induce hyperalgesia independently of opioid receptor activity. Thus, here we examined whether fentanyl increases nociception on the tail-withdrawal test in CD-1 mice concurrently treated with the opioid receptor antagonist naltrexone or in opioid receptor triple knock-out mice lacking mu, delta, and kappa opioid receptors. For both groups, an acute fentanyl bolus dose (0.25mg/kg, s.c.) and continuous fentanyl infusion (cumulative daily dose: 10mg/kg) did not cause analgesia at any time. Instead, fentanyl significantly decreased withdrawal latencies relative to pre-drug values for the next 15-60 min and for six days, respectively. MK-801 blocked and reversed hyperalgesia caused by the acute injection and continuous infusion of fentanyl, respectively, in naltrexone-treated CD-1 mice, indicating the contribution of NMDA receptors to fentanyl hyperalgesia. These data show that the synthetic opioid fentanyl causes hyperalgesia independently of prior or concurrent opioid receptor activity or analgesia. Since the biotransformation of fentanyl does not yield any known pronociceptive metabolites, these data challenge assumptions regarding the role of neuroexcitatory metabolites in opioid-induced hyperalgesia.
authors: Neuropsychology Program, Queens College, City University of New York, Flushing, NY 11367, USA.
authors: Amanda R
authors: AR
authors: Waxman
authors: Caroline
authors: C
authors: Arout
authors: Megan
authors: M
authors: Caldwell
authors: Albert
authors: A
authors: Dahan
authors: Benjamin
authors: B
authors: Kest
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005283:Fentanyl / Q000008:administration & dosage / Q000494:pharmacology*; D006358:Hot Temperature; D006930:Hyperalgesia / Q000139:chemically induced* / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000008:administration & dosage / Q000494:pharmacology*; D010146:Pain / Q000188:drug therapy; D010147:Pain Measurement; D011957:Receptors, Opioid / Q000235:genetics / Q000378:metabolism*; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D018691:Excitatory Amino Acid Antagonists; D009292:Narcotic Antagonists; D009294:Narcotics; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D009271:Naltrexone; D016291:Dizocilpine Maleate; D005283:Fentanyl