The mesolimbic dopaminergic system has been implicated in mediating the motivational effects of opioids and other drugs of abuse. The site of action of opioids within this system and the role of endogenous opioid peptides in modulating dopamine activity therein remain unknown. Employing the technique of in vivo microdialysis and the administration of highly selective opioid ligands, the present...

Abstract Background Acute identification and treatment of myocardial infarction (MI) is crucial for survival. MI symptom presentation typically characterized by chest pain. Regular use opioids to relief pain chronic diseases common. However, it has not been investigated whether opioid administered prior onset associated more with atypical ischemia compared non-opioid users. Purpose To investiga...

Stimulation of the brain CCK2 receptor by the C-terminal octapeptide CCK8 of cholecystokinin (CCK) negatively modulates opioid responses. This suggests the existence of physiologically relevant interactions between endogenous CCK and opioid peptides, opening new perspectives particularly in the treatment of pain or drug addiction. CCK2 receptor-deficient mice were used to analyze the incidence ...

Despite the demonstration that chronic morphine increases phosphorylation of multiple substrate proteins, their identity has, for the most part, remained elusive. Thus far, chronic morphine has not been shown to increase the phosphorylation of any identified effector protein. This is the first demonstration that persistent activation of opioid receptors has profound effects on phosphorylation o...

Nociceptin, the endogenous ligand of the inhibitory G protein-coupled opioid receptor-like 1 receptor, produces aquaresis (i.e., increases the excretion of solute-free urine) in rats. However, the mechanism underlying this effect has not yet been explained. Using immunohistochemistry, we found the opioid receptor-like 1 receptor in the rat kidney colocalized with the vasopressin-regulated water...

Accumulating evidence has indicated that membrane-permeable G protein-coupled receptor ligands can enhance cell surface targeting of their cognate wild-type and mutant receptors. This pharmacological chaperoning was thought to result from ligand-mediated stabilization of immature receptors in the endoplasmic reticulum (ER). In the present study, we directly tested this hypothesis using wild-typ...

A large body of evidence indicates important interactions between the adenosine and opioid systems in regulating pain at both the spinal and supraspinal level. Mice lacking the A2A receptor gene have been developed successfully, and these animals were shown to be hypoalgesic. To investigate whether there are any compensatory alterations in opioid systems in mutant animals, we have performed qua...

Background: A number of drugs are used to control opioid withdrawal symptoms during detoxification. Tramadol, as a partial opioid agonist, has been widely used to manage acute and chronic pains. The present study was designed to assess the effectiveness of tramadol in methadone-assisted detoxification. Methods: In a double-blind randomized clinical trial 72 opioid-dependent patients as defined ...

Whole-cell patch-clamp recordings were used to characterize calcium channel types that are modulated by mu-opioid receptor activation in rat dorsal root ganglion (DRG) neurons. Five distinct components of high-threshold calcium current were isolated on the basis of their sensitivity to the selective channel blockers omega-conotoxin GVIA, nifedipine, omega-conotoxin MVIIC, or omega-agatoxin IVA....

The number of available opioid preparations, each with differing chemical properties, structure and opioid receptor affinity, increases with time. The efficacy of these opioids in the treatment of pain arising from a diverse range of disorders is beyond question. With the passage of time, the list of those conditions where an opioid is recommended as a treatment option increases, and that list ...