The ventral tegmental area (VTA) and its dopaminergic projections appear to mediate some of the rewarding properties of opiates, cocaine, and other drugs of abuse. In a previous study, we demonstrated that chronic morphine and cocaine exert common actions on tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, in this dopaminergic brain reward region (Beitner-Johnson an...

Introduction: Several studies have reported anti-anxiety effects of morphine in adult rats. The present study examined the effect of chronic morphine injections in infancy and before puberty on anxiety-like behavior in immature rats. Methods: Neonate rats (n=35) were randomly chosen and divided into two groups. On postnatal days 8-14, one group received saline and the other one received mor...

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...

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 inhibitor SB203580 (0.5 microg/h), morp...

BACKGROUND Although opioids suppressive effects on immune system function have been reported, this study demonstrates inflammatory reactions, such as production of pro-inflammatory cytokines and suppression of anti-inflammatory cytokines, are the main causes at organ's allotransplantation rejection in chronic morphine-treated recipients. METHODS 28 rats were categorized in 4 groups through in...

Chronic breathlessness, a persistent and disabling symptom despite optimal treatment of underlying causes, is frightening with serious widespread impact on patients their carers. Clinical guidelines support the use morphine for relief chronic breathlessness in common long-term conditions, but questions remain around clinical effectiveness, safety longer-term (>7 days) administration. This tr...

Previous studies in humans and animals have reported that nicotine administration decreases body weightand caloric intake. Opiate and cigarette have been used concomitantly as drug abuse. The aim of the present study was, therefore, to analyze the effect of chronic co-administration of nicotine and morphine on food intake, body weight and on some feeding-associated peptides. All experiments wer...

There is growing appreciation for the importance of gastrointestinal microbiota in many physiological and pathophysiological processes. While morphine and other narcotics are the most widely prescribed therapy for moderate to severe pain clinically, they have been noted to alter microbial composition and promote bacterial translocation to other tissues. Here we examined the pharmacodynamic prop...

Morphine loses analgesic potency after repeated administration. The underlying mechanism is not fully understood. Glia are thought to be involved in morphine tolerance, and P2X7 purinergic receptor (P2X7R) has been implicated in neuron– glia communication and chronic pain. The present study demonstrated that P2X7R immunoreactivity was colocalized with the microglial marker OX42, but not the ast...

Morphine is an opiate alkaloid characterized by various clinical effects, among which the most prominent are its analgesic and psychoactive effects. It also has a depressive effect on respiratory cardiovascular system. Because of effect, morphine very addictive often used as recreational narcotic. As medication, it found use agent in chronic pain treatment, hemorrhagic shock, acute heart failur...