Uncertainty about the clinical significance of tolerance to opioid analgesia has important and diverse implications. Although understanding of the characteristics and mechanisms of experimental tolerance has grown, the clinical correlates and ramifications of these findings remain ambiguous to practitioners prescribing long-term opioid therapy to patients for the treatment of malignant and non-...

The nonopioid actions of spinal dynorphin may promote aspects of abnormal pain after nerve injury. Mechanistic similarities have been suggested between opioid tolerance and neuropathic pain. Here, the hypothesis that spinal dynorphin might mediate effects of sustained spinal opioids was explored. Possible abnormal pain and spinal antinociceptive tolerance were evaluated after intrathecal admini...

Formalin as a chemical noxious stimulus evokes a biphasic pain that its second phase as a chronic inflammatory pain is similar to clinical pain. In this study, we used 40 NMRI male rats (250-300 g), and experiments were carried out considering ethical rules. Experiments were performed in normal and morphine addicted rats, the addiction was induced by Leung method. Behaviors of flinching and lic...

Hyperalgesia is a common clinical phenomenon among opioid dependent patients on methadone maintenance therapy (MMT) and it may be associated with undertreated pain and/or therapeutic failure. This study aimed to investigate association between serum methadone concentration (SMC) and cold pressor pain responses. Cold pressor pain responses in 147 opioid dependent patients on MMT were assessed us...

Formalin as a chemical noxious stimulus evokes a biphasic pain that its second phase as a chronic inflammatory pain is similar to clinical pain. In this study, we used 40 NMRI male rats (250-300 g), and experiments were carried out considering ethical rules. Experiments were performed in normal and morphine addicted rats, the addiction was induced by Leung method. Behaviors of flinching and lic...

BACKGROUND Acute chest pain constitutes a considerable diagnostic challenge outside hospitals. This will often lead to uncertainty in choosing the right management, and the physicians' approach may be influenced by their knowledge of diagnostic measures and their tolerance of risk. The aim of this study was to investigate primary care physicians' diagnostic approach, tolerance of risk and attit...

BACKGROUND Tolerance to the analgesic effect of morphine complicates the management of chronic pain states. The authors studied the ability of the glycine/N-methyl-D-aspartate receptor antagonist (+)-HA966 to modify morphine tolerance in a rat model of neuropathic pain. METHODS Mononeuropathy was induced by placing four ligatures around the common sciatic nerve. The 4-day pretreatment regimen...

Models of stress-induced hyperalgesia state that exposure to stress can exaggerate subsequent pain experiences. Studies using both animal and human subjects have shown evidence for hyperalgesia as a function of stress [e.g., Jorum E. Analgesia or hyperalgesia following stress correlates with emotional behavior in rats. Pain 1988;32:341-48; Peckerman A, Hurwitz BE, Saab PG, Llabre MM, McCabe PM,...

BACKGROUND Analgesic effect of exercise is a well established fact; however available reports are contradictory on gender differences in pain perception following exercise stress test. OBJECTIVE The current study is prospectively designed to evaluate and compare the effect of acute bout of sub-maximal exercise stress on cold pressor pain in normal adult males and females. METHOD The experim...