‎ introduction: controversial results have been reported about the effect of morphine and stress on learning and spatial memory in rodents. there are very few studies about the effects of ultra low doses of morphine on memory. in this study, effects of acute administration of low and usual doses of morphine on memory formation and retention in the presence and absence of repeated stress were in...

introduction: in the kindling-induced seizure model, low and repeated electrical or chemical stimulations, can elevate the neural network excitability and induce epileptiform seizures. opioid receptors are widely distributed in different areas of the brain. on the other hand, morphine has paradoxical effects and induces elevation or alleviation of the pain sensation and excitability, at differe...

Introduction: In the Kindling-induced seizure model, low and repeated electrical or chemical stimulations, can elevate the neural network excitability and induce epileptiform seizures. Opioid receptors are widely distributed in different areas of the brain. On the other hand, morphine has paradoxical effects and induces elevation or alleviation of the pain sensation and excitability, at diff...

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...

BACKGROUND The development of analgesic tolerance following chronic morphine administration can be a significant clinical problem. Preclinical studies demonstrate that chronic morphine administration induces spinal gliosis and that inhibition of gliosis prevents the development of analgesic tolerance to opioids. Many studies have also demonstrated that ultra-low doses of naltrexone inhibit the ...

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 ...

Ultra-low doses of non-selective α2-adrenoceptor antagonists augment acute spinal morphine antinociception and block morphine tolerance; however, the receptor involved in mediating these effects is currently unknown. Here, we used tail flick and paw pressure tests on the rat to investigate the acute analgesic and tolerance-inducing effects of spinal morphine and norepinephrine alone or in combi...

Introduction: Uncoupling protein 2 (UCP2) in the inner mitochondrial membrane changes the activity of KATP channels and the cell excitability, probably by decreasing the ATP production. Given the expression of UCP2 in primary afferent neurons, and the importance of these channels in morphine-induced analgesia, genipin, an UCP2 inhibitor, may affect these processes, when administrated intrath...

It has been shown that systemic administration of morphine induced a hyperalgesic response at an extremely low dose. We have examined the effect of nifedipine, as a calcium channel blocker, on morphine-induced hyperalgesia in intact and adrenalectomized rats and on hypothalamic-pituitary-adrenal axis activity induced by ultra-low dose of morphine. To determine the effect of nifedipine on hypera...