Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities

Abstract

Opioid-induced hyperalgesia and tolerance severely impact the clinical efficacy of opiates as pain relievers in animals and humans. The molecular mechanisms underlying both phenomena are not well understood and their elucidation should benefit from the study of animal models and from the design of appropriate experimental protocols.We describe here a methodological approach for inducing, recording and quantifying morphine-induced hyperalgesia as well as for evidencing analgesic tolerance, using the tail-immersion and tail pressure tests in wild-type mice. As shown in the video, the protocol is divided into five sequential steps. Handling and habituation phases allow a safe determination of the basal nociceptive response of the animals. Chronic morphine administration induces significant hyperalgesia as shown by an increase in both thermal and mechanical sensitivity, whereas the comparison of analgesia time-courses after acute or repeated morphine treatment clearly indicates the development of tolerance manifested by a decline in analgesic response amplitude. This protocol may be similarly adapted to genetically modified mice in order to evaluate the role of individual genes in the modulation of nociception and morphine analgesia. It also provides a model system to investigate the effectiveness of potential therapeutic agents to improve opiate analgesic efficacy.

Acetylated tubulin is essential for touch sensation in mice

“…The tape test (Ranade et al, 2014), cotton swab (Ranade et al, 2014), von Frey (Kwan et al, 2006), tail clip (Ranade et al, 2014), hot plate (Kwan et al, 2006), tail immersion test (Elhabazi et al, 2014), acetone drop (Choi et al, 1994) and rotarod assay (Hamm et al, 1994) respectively, were all performed as described previously. The grid test was performed by counting the number of steps versus slips over 2 min from a free roaming mouse placed atop a metal grid.…”

Stable isotope‐labelled morphine to study in vivo central and peripheral morphine glucuronidation and brain transport in tolerant mice

“…However, in vivo longitudinal studies in animals and humans could be achieved using different stable isotope‐labelled precursors (d3‐morphine, d6‐morphine …) and periodical MS analysis of blood, urine, as well as microdialysis samples. Furthermore, while our protocol for the induction of tolerance is widely accepted (Ueda et al ., ; Elhabazi et al ., ), it does not accurately reflect the morphine treatment schedule in patients. Thus, our study's clinical relevance could benefit from using extended release morphine formulations or from increasing the number of injections per day.…”

“…However, in vivo longitudinal studies in animals and humans could be achieved using different stable isotope-labelled precursors (d3-morphine, d6morphine …) and periodical MS analysis of blood, urine, as well as microdialysis samples. Furthermore, while our protocol for the induction of tolerance is widely accepted (Ueda et al, 1997;Elhabazi et al, 2014), it does not…”

TRPC1/4/5 channels contribute to morphine‐induced analgesic tolerance and hyperalgesia by enhancing spinal synaptic potentiation and structural plasticity

“…The thermal sensitivity was assessed before and 30 min after morphine treatment using tail immersion test as described previously 28 . In brief, the temperature of the water bath was set at 48°C.…”