Tolerance to opioid administration represents a serious medical alert in different chronic conditions. This study compares the effects of the imidazoline compounds 1, 2, and 3 on morphine tolerance in an animal model of inflammatory pain in the rat. 1, 2, and 3 have been selected in that, although bearing a common scaffold, preferentially bind to α2-adrenoceptors, imidazoline I2 receptors, or b...

The present study focused on the role of peripheral ionotropic N-methyl-D-aspartate (NMDA) receptors in the development of tolerance to morphine-induced antinociception. An initial experiment revealed that NMDA channel blocker memantine, and NMDA receptor/glycine(B) site antagonist MRZ 2/576 inhibited maximal electroshock-induced convulsions (MES) in female NMR mice with respective potency of 5...

The aim of this study was to evaluate the effect of ethanol and morphine on nociceptive behavioral responses evoked by the injection of formalin into the temporomandibular joint region of rats (the TMJ formalin test). In experiment 1, animals were given an ethanol solution (6.5%) or tap water to drink for 4 and 10 days, before the procedure for TMJ pain. In the group treated for 4 days, signifi...

hanges in the concentration of either brain or blood glucose level appear to modulate antinociceptive and basal nociceptive processes. There are some contradictory data about the effect of diabetes on morphine antinociception. In this study the effects of alloxan-induced diabetes on morphine analgesia, tolerance and dependency were investigated, with a view to clarify the contradictions. Materi...

BACKGROUND The efficacy of opioids for neuropathic pain remains controversial. The effects of morphine on pain behavior were investigated in two animal models of neuropathic pain: the spared nerve injury (SNI) model and the spinal nerve ligation (SNL) model. METHODS Nerve injuries were created in rats either by tight ligation and section of the left tibial and common peroneal nerves (SNI) or ...

BACKGROUND The spinal administration of some N-methyl-d-aspartate receptor antagonists results in antinociception and potentiates the effects of opioids and alpha2-adrenoceptor agonists, but ketamine and its enantiomers have not been examined. The present study investigated the interactions of racemic ketamine, R(-)-ketamine and S(+)-ketamine with morphine and with dexmedetomidine. METHODS In...

BACKGROUND Combining different analgesic drugs for improvement of drug efficacy is a recommended strategy intended to achieve the optimal therapeutic effects. OBJECTIVES The purpose of the present study was to assess the nature of the interaction between ascorbic acid and two analgesic drugs, morphine and tramadol. MATERIALS AND METHODS The analgesic activity was assessed by the acetic acid...

Opioid-induced hyperalgesia is characterized by hypersensitivity to innocuous or noxious stimuli during sustained opiate administration. Microinjection of lidocaine into the rostral ventromedial medulla (RVM), or dorsolateral funiculus (DLF) lesion, abolishes opioid-induced hyperalgesia, suggesting the importance of descending pain facilitation mechanisms. Here, we investigate the possibility t...

background combining different analgesic drugs for improvement of drug efficacy is a recommended strategy intended to achieve the optimal therapeutic effects. objectives the purpose of the present study was to assess the nature of the interaction between ascorbic acid and two analgesic drugs, morphine and tramadol. materials and methods the analgesic activity was assessed by the acetic acid wri...