Short-term morphine stimulates vagal bradycardia. This led us to propose the hypothesis that chronically administered morphine would down-regulate myocardial muscarinic receptor systems. Dogs received morphine continuously for 2 weeks through an s.c. catheter, and cellular aspects of parasympathetic control of the heart were examined. Contrary to expectations, morphine increased muscarinic rece...

OBJECTIVES This research aims at studying the neuroendocrine effects of music on creating morphine dependence in mice using conditioned place preference (CPP). METHODS The mice treated with 10 mg/kg morphine subcutaneously, fast music and slow music. Morphine was used to create dependence. In order to recognize the morphine rewarding effects, CPP technique was used. In the conditioning stage ...

OBJECTIVES Central nucleus of amygdala (CeA) is the most important region for morphine-induced reward, and GABAergic system plays an important role on morphine reinforcement. The influence of CeA administration of GABAB receptor agonist and antagonist on the expression and acquisition of morphine-induced incentive tolerance using conditioned place preference (CPP) paradigm was investigated in t...

It has been shown that systemic administration of morphine induced a hyperalgesic response at an extremely low dose. We have examined the effect of nifedipine, as a calcium channel blocker, on morphine-induced hyperalgesia in intact and adrenalectomized rats and on hypothalamic-pituitary-adrenal axis activity induced by ultra-low dose of morphine. To determine the effect of nifedipine on hypera...

Morphine analgesia in mice was significantly potentiated by pretreatment with 5-hydroxytryptophan (5-HTP), especially with higher dose of morphine. Morphine analgesia was antagonised by reserpine. With l-dopa it was antogonised when the dose of morphine was minimal but with increased dosage of morphine, there was no significant effect.

Chronic morphine administration shifts delta-opioid receptors (DORs) from the cytoplasm to the plasma membrane. Given that microinjection of morphine into the PAG produces antinociception, it is hypothesized that the movement of DORs to the membrane will allow antinociception to the DOR agonist deltorphin II as a way to compensate for morphine tolerance. Tolerance was induced by twice daily inj...

The primary site for the metabolism of morphine has been the subject of controversy for some time. We studied morphine metabolism during the anhepatic phase of orthotopic liver transplantation in seven adult patients. After injection of morphine 10 mg at the beginning of this phase, the plasma and urinary concentrations of unchanged morphine, morphine-3-glucuronide, morphine-6-glucuronide and n...

Morphine has been widely accepted as the opioid agonist that sustains signaling because it does not cause receptor desensitization or internalization. This notion has led to the hypothesis that long-term morphine treatment initiates downstream adaptations that underlie tolerance and dependence. This study uses whole-cell recordings from neurons in the locus ceruleus to measure the potassium cur...

objective: in the present study, the effects of aqueous saffron extract (crocus sativus l.) on the acquisition and reinstatement of morphine-induced conditioned place preference (cpp) in mice were investigated. materials and methods: subcutaneous administration of morphine (40 mg/kg for four days) produced place preference. intraperitoneal administration of aqueous extract (40 and 80 mg/kg for ...

The aim of this study was to test whether morphine prevents the mitochondrial permeability transition pore (mPTP) opening through Zn(2+) and glycogen synthase kinase 3beta (GSK-3beta). Fluorescence dyes including Newport Green Dichlorofluorescein (DCF), 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM), and tetramethylrhodamine ethyl ester (TMRE) were used to image free Zn(2+), nitric ox...