Morphine administered simultaneously to intracerebroventricular (i.c.v.) and intrathecal (i.t.) sites exhibits synergism, with the antinociceptive potency much greater than would be predicted from a simple addition of the potencies of the same dose administered to either site alone. This synergism was quantified in mice using both a fixed dose method, in which the morphine dose at one site was ...

Misra et al. (1971) found that 1 h after a single subcutaneous injection of [N-Me-l4C1morphine into the rat, three radioactive compounds could be extracted from the cerebral cortex, namely free morphine, morphine 3-glucuronide and a ‘non-acid-hydrolysable’ conjugate. The regional and subcellular distribution of morphine and its metabolites in brain after subcutaneous injection has never been st...

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 ...

BACKGROUND To investigate clinical variables such as gestational age, sex, weight, the therapeutic regimens used and mechanical ventilation that might affect morphine requirements and plasma concentrations of morphine and its metabolites. METHODS In a double-blind study, neonates and infants stratified for age [group I 0-4 weeks (neonates), group II > or =4-26 weeks, group III > or =26-52 wee...

Morphine administered nasally to humans as a simple solution is only absorbed to a limited degree, with a bioavailability of the order of 10% compared with intravenous administration. This article describes the development of novel nasal morphine formulations based on chitosan, which, in the sheep model, provide a highly increased absorption with a 5- to 6-fold increase in bioavailability over ...

As long-term opioids are increasingly used for control of chronic pain, how pain affects the rewarding effect of opioids and hence risk of prescription opioid misuse and abuse remains a healthcare concern and a challenging issue in current pain management. In this study, using a rat model of morphine self-administration, we investigated the molecular mechanisms underlying the impact of pain on ...

Opiates have been reported to induce T cell loss. We evaluated the role of vitamin D receptor (VDR) and the activation of the renin-angiotensin system (RAS) in morphine-induced T cell loss. Morphine-treated human T cells displayed downregulation of VDR and the activation of the RAS. On the other hand, a VDR agonist (EB1089) enhanced T cell VDR expression both under basal and morphine-stimulated...

Drug addiction is increasingly viewed as the expression of abnormal associative learning following repeated exposures to the drugs of abuse. Previous studies have demonstrated that the patterns of repetition such as frequency and spacing are important to many kinds of learning and memory retention. We hypothesized that drug repetition pattern might affect the reward-related learning although th...

The present study aimed to investigate the stability of morphine, morphine-3-β-glucuronide (M3G), morphine-6-β-glucuronide (M6G), 6-acetylmorphine (6-AM) from heroin metabolites, and codeine, codeine-6-glucuronide, nor-codeine, fentanyl, norfentanyl, paracetamol, caffeine its adulterants at room temperature for 24 hours in order understand effect instability postmortem redistribution (PMR). m...

The increasing prescription of opioids is fueling an epidemic of addiction and overdose deaths. Morphine is a highly addictive drug characterized by a high relapse rate - even after a long period of abstinence. Serotonin (5-HT) neurotransmission participates in the development of morphine dependence, as well as the expression of morphine withdrawal. In this study, we examined the effect of bloc...