Background: Although opioids suppressive effects on immune system function have been reported, this study demonstrates inflammatory reactions, such as production of pro-inflammatory cytokines and suppression of anti-inflammatory cytokines, are the main causes at organ’s allotransplantation rejection in chronic morphine-treated recipients. Methods: 28 rats were categorized in 4groups through int...

Background: Chronic usage of morphine elicits the production of inflammatory factors by glial cells andinduces neuroinflammation. Ginger (Zingiber Officinale Roscoe) is a medicinal herb that has antiinflammatory properties. It has been reported that ginger shows anti-addictive effects against chronic usageof morphine; however, its influence o...

Chronic morphine exposure can induce addiction and affect synaptic plasticity, but the underlying neuronal mechanisms remain unknown. Two forms of short-term synaptic depression (paired-pulse depression (PPD) and frequency depression) were investigated in vivo in the geniculo-cortical visual pathway of morphine-treated and saline-treated (as control) adult rats. Acute exposure to morphine had n...

Chronic morphine administration induces functional and morphological alterations in the mesolimbic dopamine system (MLDS), which is believed to be the neurobiological substrate of opiate addiction. Our previous studies have demonstrated that peripheral electrical stimulation (PES) can suppress morphine withdrawal syndrome and morphine-induced conditioned place preference (CPP) in rats. The pres...

Although there is now evidence of a role for N-methyl-D-aspartate (NMDA) receptors in nucleus accumbens (NAcc) neurons in the effects of chronic opiate treatment, the cellular and molecular mechanisms underlying this phenomenon are still unclear. Therefore, we studied the effects of chronic morphine on the pharmacological and biophysical properties of NMDA receptors in freshly isolated medium s...

It has been shown that stress and chronic pain could prevent the development of tolerance to morphine analgesia, which appears to be related to the activation of hypothalamus–pitutitary–adrenal (HPA) axis, activation of neuroendocrine systems and changes in neurochemical levels. Moreover, the involvement of nitric oxide (NO) in the development of tolerance to morphine analgesia has been implica...

It has been shown that stress and chronic pain could prevent the development of tolerance to morphine analgesia, which appears to be related to the activation of hypothalamus–pitutitary–adrenal (HPA) axis, activation of neuroendocrine systems and changes in neurochemical levels. Moreover, the involvement of nitric oxide (NO) in the development of tolerance to morphine analgesia has been implica...

We previously reported that beta-adrenergic receptors are increased in cerebral cortex and hippocampus in rats treated chronically with morphine and subsequently down-regulated after morphine withdrawal [22,23]. The changes in receptor density in hippocampus were accompanied by a corresponding super- and subsensitivity, respectively, in beta-adrenergic responsiveness, as assessed electrophysiol...

Opioids, acting at μ opioid receptors, are commonly used for pain management. Chronic opioid treatment induces cellular adaptations, which trigger long-term side effects, including constipation mediated by enteric neurons. We tested the hypothesis that chronic opioid treatment induces alterations of μ opioid receptor signaling in enteric neurons, which are likely to serve as mechanisms underlyi...

Key pecking by 3 pigeons was maintained by a multiple fixed-ratio 10, fixed-ratio 30, fixed-ratio 90 schedule of food presentation. Components differed with respect to amount of reinforcement, such that the unit price was 10 responses per 1-s access to food. Acute administration of morphine, l-methadone, and cocaine dose-dependently decreased overall response rates in each of the components. Wh...