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The present study was performed to evaluate the effects of the tricyclic antidepressant amitriptyline on morphine tolerance in rats. Male Wistar rats were implanted with two intrathecal (i.t.) catheters with or without a microdialysis probe, then received a continuous i.t. infusion of saline (control) or morphine (15 microg/h) and/or amitriptyline (15(More)
In this study, the metabolic ratios of dextromethorphan to dextrorphan (DM/DX) in plasma were calculated at steady state after administering 2 dosage forms (Medicon) and Detusiv) of DM with different release rates. The urinary metabolic ratio for each subject was also determined based on the total drug concentration in the urine. An analysis of(More)
BACKGROUND This study explores the underlying mechanism of the antiinflammatory effect of amitriptyline in chronic morphine-infused rats. METHODS Male Wistar rats were implanted with two intrathecal catheters. One catheter was for the continuous infusion of saline, amitriptyline (15 microg/h), morphine (15 microg/h), p38 mitogen-activated protein kinase(More)
Morphine is one of the most effective analgesics in clinic to treat postoperative pain or cancer pain. A major drawback of its continuous use is the development of tolerance and dependence. In our previous study we found that a widely used antitussive agent in clinics, dextromethorphan [(DM); also known as a non-competitive N-methyl-d-aspartate (NMDA)(More)
Two potent endogenous opioid peptides, endomorphin-1 (EM-1) and -2 (EM-2), which are selective micro-opioid agonists, have been identified from bovine and human brain. These endomorphins were demonstrated to produce a potent anti-allodynic effect at spinal level. In the present study, we further investigated their supraspinal anti-allodynic effects and(More)
Previously we showed that coadministration of dextromethorphan (DM) with morphine attenuates morphine-rewarding effect. Here we further investigated if DM is effective in reversing or treating drug-seeking effect when given after subchronic morphine treatment. The conditioned place preference (CPP) test was used to investigate the rewarding and drug-seeking(More)
BACKGROUND Chronic use of morphine causes rewarding effects and behavioral sensitization, which may lead to the development of craving for morphine. A number of studies indicate that the NMDA receptors may be involved in these effects, especially the NR2B-containing NMDA receptors. It is also well recognized that the nucleus accumbens (NAc) and the ventral(More)
The present study was undertaken to examine the effect of amitriptyline on the antinociceptive effect of morphine and its underlying mechanisms in regulating glutamate transporters trafficking in morphine-tolerant rats. Long-term morphine infusion induced antinociceptive tolerance and down-regulation of glutamate transporters (GTs), GLAST, GLT-1, and EAAC1,(More)
The central nervous system (CNS) exhibits remarkable plasticity in early life and can be altered significantly by various prenatal influences. We previously showed that prenatal exposure to morphine altered kinetic properties of N-methyl-D-aspartate (NMDA) receptor-mediated synaptic currents in the hippocampus of young rat offspring at the age of 14 days(More)
The present study has investigated the possible supraspinal adaptive changes induced by prenatal administration of morphine, including morphine-induced supraspinal antinociception in vivo, the density and binding affinity of mu-opioid receptors in the brain and the cellular action of morphine in brain slices in vitro. The cellular action of morphine was(More)