Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (UMR5287)

Aquitaine Institute for Cognitive and Integrative Neuroscience

Université de Bordeaux

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33076 Bordeaux cedex


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CNRS Ecole Pratique des Hautes Etudes Université de Bordeaux

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Home > Latest publications

Fentanyl-induced hyperalgesia and analgesic tolerance in male rats: common underlying mechanisms and prevention by a polyamine deficient diet

by Loïc Grattier - published on

Emilie Laboureyras , Meric Ben Boujema , Annie Mauborgne , John Simmers
, Michel Pohl and Guy Simonnet

Neuropsychopharmacology (2022) 47:599–608

Abstract :

Opioids are a mainstay of pain management but can induce unwanted effects, including analgesic tolerance and paradoxical hyperalgesia, either of which leads to increased pain. Clinically, however, the relationship between these two phenomena remains elusive. By evaluating changes in mechanical nociceptive threshold in male rats, we found that in contrast to a purely analgesic control response to a single subcutaneous administration of fentanyl (25 μg/kg), in rats subjected to inflammatory pain 2 weeks previously (Day0), the same test dose (D13) induced a bi-phasic response: initial decreased analgesia (tolerance) followed by hyperalgesia lasting several hours. Both the tolerance and hyperalgesia were further enhanced in rats that had additionally received fentanyl on D0. The dose-response profiles (5 fg to 50 μg/kg) of pain- and opioid-experienced rats were very different from pain/ drug-naive rats. At ultra-low fentanyl doses (<5 ng/kg and <500 ng/kg for naïve control and pain/drug-experienced rats, respectively), solely hyperalgesia was observed in all cases. At higher doses, which now produced analgesia alone in naive rats, reduced analgesia (tolerance) coupled with hyperalgesia occurred in pain/fentanyl-experienced rats, with both phases increasing with dose. Transcriptomic and pharmacological data revealed that an overactivation of the spinal N-methyl-D-aspartate receptorinducible NO synthase cascade plays a critical role in both acute tolerance and hyperalgesia, and together with the finding that the magnitudes of analgesia and associated hyperalgesia are negatively correlated, is indicative of closely related phenomena. Finally, a polyamine deficient diet prevented inducible NO synthase transcript upregulation, restored fentanyl’s analgesic efficacy and suppressed the emergence of hyperalgesia.

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