introduction: ultra low dose (uld) morphine induces hyperalgesia which is mediated by excitatory gscoupled opioid receptors. this study was designed to investigate the development of tolerance to hyperalgesic effect of morphine. also we attempt to seek possible similarity, in view of gs proteins, between hyperalgesic effect of uld and hyperalgesic effect after tolerance to hd. method: male wist...

Introduction: Ultra low dose (ULD) morphine induces hyperalgesia which is mediated by excitatory Gscoupled opioid receptors. This study was designed to investigate the development of tolerance to hyperalgesic effect of morphine. Also we attempt to seek possible similarity, in view of Gs proteins, between hyperalgesic effect of ULD and hyperalgesic effect after tolerance to HD. Method: Male ...

Opioids, the wonderful analgesics, remain the mainstay in the clinical management of moderate to severe pain. However, development of analgesic tolerance and increase in pain sensitivity are some of the major concerns following opioid treatment. Studies suggest that NMDA receptor-mediated intracellular events play a role in mediating these effects. Moreover, NMDA receptor antagonists effectivel...

introduction: in order to study the alterations of beta 1 and 2 integrins mrna level in rat lumbar spinal cord following the induction of chronic pain and its effect on the development of tolerance to morphine analgesia, we examined the level of expression of these genes in the presence of chronic pain, which is an inhibitor of morphine tolerance. we used induction of chronic pain alone and in ...

Previous studies have shown that the extract of Papaver rhoeas reduces morphine dependence, locomotor activity and reward. In present study, the effects of hydro-alcohol extract of Papaver Rhoeas on the tolerance to analgesic effects of morphine in mice have been investigated using tail flick method. Subcutaneous (s.c.) administration of morphine (1, 2, 5 and 10 mg/kg) induced analgesia. Howeve...

Previous studies have shown that the extract of Papaver rhoeas reduces morphine dependence, locomotor activity and reward. In present study, the effects of hydro-alcohol extract of Papaver Rhoeas on the tolerance to analgesic effects of morphine in mice have been investigated using tail flick method. Subcutaneous (s.c.) administration of morphine (1, 2, 5 and 10 mg/kg) induced analgesia. Howeve...

GABAergic drugs can change analgesic effect of morphine. Wide dynamic range (WDR) neurons play an important role in pain transmission and may change behaviors in morphine tolerance. In this study WDR neuron behaviors in morphine tolerant rats and rats treated with GABA agonists, were recorded to elucidate the effect of morphine and GABA agonists on WDR behavioral changes. Rats were divided to 4...

GABAergic drugs can change analgesic effect of morphine. Wide dynamic range (WDR) neurons play an important role in pain transmission and may change behaviors in morphine tolerance. In this study WDR neuron behaviors in morphine tolerant rats and rats treated with GABA agonists, were recorded to elucidate the effect of morphine and GABA agonists on WDR behavioral changes. Rats were divided to 4...

Morphine loses analgesic potency after repeated administration. The underlying mechanism is not fully understood. Glia are thought to be involved in morphine tolerance, and P2X(7) purinergic receptor (P2X(7)R) has been implicated in neuron-glia communication and chronic pain. The present study demonstrated that P2X(7)R immunoreactivity was colocalized with the microglial marker OX42, but not th...