Our investigation was aimed at elucidating if the chronic administration and withdrawal of a preferential mu-agonist, morphine, induce changes on the heart catecholaminergic neuronal activity. With this purpose the effects of morphine or naloxone (preferentially mu-antagonist) on noradrenaline, adrenaline or dopamine (DA) content and the mechanical response of the left atria were studied in chr...

Physical dependence on morphine is evidenced by the withdrawal syndromes, including body weight loss, which are induced by the discontinuation of morphine exposure or by the treatment with naloxone, an opioid receptor antagonist. The present study was designed to examine whether the elevation of serum corticosterone (SCS) level induced by naloxone-precipitated morphine withdrawal was a useful i...

Peripheral administration of naloxone is known to produce a conditioned place aversion and to block cocaine-induced conditioned place preference. The ventral pallidum receives a dense enkephalinergic projection from the nucleus accumbens and is implicated as a locus mediating the rewarding and reinforcing effects of psychostimulant and opiate drugs. We sought to provide evidence for the involve...

OBJECTIVE Studies have consistently shown that long-term meditation practice is associated with reduced pain, but the neural mechanisms by which long-term meditation practice reduces pain remain unclear. This study tested endogenous opioid involvement in meditation analgesia associated with long-term meditation practice. METHODS Electrical pain was induced with randomized, double-blind, cross...

Tramadol is used in treatment of moderate to severe pain. Nowadays tramadol overdose is one of the common emergencies. Naloxone is an antagonist which is used as a first step of treatment in these patients. This study was designed to evaluate the seizurogenic effects of naloxone in tramadol overdose. A number of 124 patients with the diagnosis of tramadol overdose were divided to receive lo...

Opioid dependence in ventrolateral periaqueductal gray (PAG) neurons was studied by using intracellular recordings from brain slices. In slices from morphine-dependent rats maintained in morphine (5 microM) in vitro, action potential frequencies of opioid-sensitive neurons did not differ from untreated control neurons but were greater than in control neurons maintained in morphine in vitro, ind...

Using quantitative receptor autoradiography, [3H]D-Ala-D-Leu-enkephalin (DADL) and [3H]naloxone binding were studied in rat striatum and striatal projection areas (globus pallidus (GP) and substantia nigra pars reticulata (SNr] after unilateral striatal kainic acid lesions. [3H]DADL and [3H]naloxone binding were each examined by two methods. Initially, [3H]DADL binding was performed in 50 mM Tr...

Experiment 1: It is well known that the social context powerfully influences behaviour. Here we examine whether it also influences drug-seeking. Further, acamprosate and naloxone have been discussed to affect different types of craving: acamprosate was reported to affect withdrawalcraving, while naloxone affects reward-craving. Conditioned drug-seeking was modelled using the conditioned place p...

BACKGROUND Opioid overdose is a leading cause of death among injection drug users. Over half of injection drug users report at least one nonfatal overdose during their lifetime. Death from opioid overdose rarely occurs instantaneously, but rather over the course of one to three hours, allowing ample time for providing life-saving measures. In response to the prevalence of overdoses in the U.S.,...