Repeated administration of morphine sensitizes animals to the stimulant and rewarding properties of the drug. It may also alter the expression and function of GABA receptors within the ventral tegmental area (VTA), a midbrain region that is implicated in morphine action. In the present study, the effect of activation of GABAB receptor subtypes within the VTA on morphine-induced incentive sensit...

Repeated administration of morphine sensitizes animals to the stimulant and rewarding properties of the drug. It may also alter the expression and function of GABA receptors within the ventral tegmental area (VTA), a midbrain region that is implicated in morphine action. In the present study, the effect of activation of GABAB receptor subtypes within the VTA on morphine-induced incentive sensit...

Although it was shown as long ago as the late 1930s and early 1940s that a high calcium diet prevented or delayed the development of tolerance and dependence to morphine in guinea pigs and rats [6,7], no further studies on the effect of calcium on opiate action were reported until 1966. Intracisternal or subcutaneous administration of calcium prevented the analgesic effect of morphine and meper...

in vivo microdialysis was used to study the effects of morphine on glutamate release from the ventral tegmentum area (vta) in freely moving rats. intraperitoneal (i.p.) injection of acute and repeated morphine at increasing doses significantly enhanced glutamate release. only a minor tolerance developed to this dosage of morphine. ap-s (2-amino-5-phosphonovaleric acid, 0.5 mg/kg i.p.), a nmda r...

Morphine, first characterized in opium from the poppy Papaver somniferum, is one of the strongest known analgesics. Endogenous morphine has been identified in several mammalian cells and tissues. The synthetic pathway of morphine in the opium poppy has been elucidated. The presence of common intermediates in plants and mammals suggests that biosynthesis occurs through similar pathways (beginnin...

background: role of nitric oxide (no) on expression of morphine conditioning using a solely classic task has been proposed previously. in this work, the involvement of no on the expression of opioid-induced conditioning in the task paired with an injection of naloxone was investigated. methods: conditioning was established in adult male wistar rats (weighing 200-250 g) using an unbiased procedu...

Abstract: ِIntroduction: The effect of morphine dependency on learning and spatial memory is controversial. So in this study effect of co-administeration of nitric oxide (NO) and morphine in CA3 of hippocampus on learning and spatial memory in morphine dependent rats was investigated. Methods: After anaesthetization of male rats, cannulae implanted bilaterally in CA3 of hippocampus. After reco...

In membranes from rat brain striatum, opiate agonists stimulated low-K GTPase. Half-maximal enhancement of enzyme activity was obtained with 0. 09m microM morphine and 3.8 microM levorphanol. This order of potency corresponded to that of the affinities of these compounds in binding to opiate receptor. The effect was inhibited by the antagonist naloxone. As shown by the use of the enantiomers le...

BACKGROUND Repeated morphine treatment has been shown to induce transient receptor potential vanilloid type 1 (TRPV1) expression in the spinal cord, dorsal root ganglion (DRG), and sciatic nerve of a rat model. Increased TRPV1 expression may therefore play a role in morphine tolerance. In this study, we evaluated the hypothesis that blockage of TRPV1 may be useful as an adjunctive pain manageme...