Introduction: Transient receptor potential vanilloid type 1 (TRPV1) and protein kinase Cγ (PKCγ) are involved in sensitization/desensitization to noxious stimuli. We aimed to examine the gene expression levels of TRPV1 and PKCγ in rat lumbosacral cord and midbrain on days 1, 4 and 8 of induction of morphine analgesic tolerance. Methods: Two groups of male Wistar rats received ...

This study was carried out based on the assumption that brain-derived neurotrophic factor (BDNF) may counterbalance the action of morphine in the brain. Morphine analgesic tolerance after daily administrations for six days was blocked by intracerebroventricular injection of anti-BDNF IgG on day 5, but not by administrations on days 1-4. Chronic morphine treatment significantly increased the exp...

Opioid receptors (OR) are part of the class A of G-protein coupled receptors and the target of the opiates, the most powerful analgesic molecules used in clinic. During a protracted use, a tolerance to analgesic effect develops resulting in a reduction of the effectiveness. So understanding mechanisms of tolerance is a great challenge and may help to find new strategies to tackle this side effe...

Background and objectives: Long-term exposure to opiates induces tolerance to the analgesic effect. The chronic use of opioids in glia cells produces pro-inflammatory mediators such as Tissue Necrosis Factor α and interleukins. Regarding the reports on Ocimum basilicum (Family: Lamiaceae) which has antioxidant and anti-inflammatory effects, it is probable that it could...

The relationship between the brain monoaminergic mechanism and morphine tolerance was examined in reserpinized mice. In parallel with the reduction of brain monoamine content, the analgesic effect of morphine was reduced in reserpinized animals. At the peak of the reserpine effect, 24 hr after a single dose of 2.5 mg/kg reserpine, i.p., the analgesic effect of morphine was lowered to about 45% ...

Ultra-low-dose opioid antagonists, when combined with opiates, increase the analgesic efficacy and duration of analgesia of the opiate. This enhanced and prolonged analgesia was recently demonstrated in a 350-patient Phase II clinical trial of Oxytrex, a novel drug candidate that combines oxycodone with an ultra-low dose of the opioid antagonist naltrexone. Extensive preclinical data also show ...

caffeine, an adenosine a1, a2a, and a2b receptor antagonist, is frequently used as an adjuvant analgesic in combination with non steroidal anti-inflammatory drugs or opioids. the aim of this study was to evaluate the effects of caffeine on preventing the development of morphine tolerance and analgesia in mice. in this study, different groups of mice received morphine (30 mg/kg) + saline (10 ml/...

Pain sensitivity reflects a balance between pain facilitatory and inhibitory systems. To characterize the relationships between these systems we examined the interactions between the analgesic effects of morphine and the anti-analgesic effects of the pro-inflammatory cytokine interleukin-1 (IL-1). We report that administration of a neutral dose of IL-1beta abolished morphine analgesia in mice, ...

Numerous data have indicated that competitive and non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists attenuate the development of tolerance to the analgesic effect of morphine. This study extends these findings on the effects of glycine(B) site antagonist, L-701.324. Tolerance to the analgesic effect of morphine was measured in hot-plate test in Wistar rats. For 9 days, animals we...

OBJECTIVES Morphine is widely used to treat chronic pain. However, its utility is hindered by the development of tolerance to its analgesic effects. Despite the renowned beneficial effects of physical exercise on cognitive functions and signs of morphine withdrawal in morphine-dependent rats, little is known about the roles of voluntary and forced exercises in tolerance to analgesic effect of m...