Search results for "morphine"
showing 10 items of 145 documents
Conditioned place preference paradigm can be a mouse model of relapse to opiates
2001
With the object of determining the usefulness of the conditioned place preference (CPP) paradigm as a model of relapse to opiates, the effects of the re-exposure to morphine are explored in male mice which had undergone a process of extinction of conditioning. Morphine (40 mg/kg) produces a CPP which lasts up to 15 days after conditioning. When it has completely extinguished (45 days), a non contingent re-exposure to the drug again produces the same preference. These results suggest that the CPP paradigm may be used in mice to study the mechanisms of relapse to opiates in addicts.
Effects of apomorphine on orienting reaction in the rat
2009
Aim of the research was to study the possible relationship between rapid apomorphine-induced modifications of midbrain dopaminergic neuron activity and rapid modifications of a motor response triggered by sensory stimuli (sensory-motor integration. Following apomorphine administration, ANOVA test revealed significant decrease of head turning latency and duration. A change on dopamine release, leading to an inhibition or facilitation of dopamine-mediated responses to environmental stimuli, may be hypothesized.
Phenothiazines interfere with dopaminergic neurodegeneration in Caenorhabditis elegans models of Parkinson's disease
2010
Oxidative stress is involved in the pathogenesis of various neurodegenerative disorders, conventional antioxidant strategies have yet been of limited success. We have employed transgenic Caenorhabditis elegans expressing DsRed2 in dopaminergic neurons and CFP pan-neuronally, to characterize in larval and adult animals the effects of rotenone and 1-methyl-4-phenyl-pyridinium (MPP(+)) on the dopaminergic system. Investigating the antioxidant phenothiazine and different derived antipsychotic drugs, it was found that free phenothiazine exerted strong neuroprotection at the cellular level and resulted in a better performance in behavioral assays, whereas apomorphine and other dopamine agonists o…
Long-lasting rewarding effects of morphine induced by drug primings.
2005
To evaluate the persistence of the rewarding effects of morphine, the acquisition, maintenance, extinction and reinstatement of a conditioned place preference (CPP) was assessed in OF1 mice. In Experiment 1, the persistence of morphine-induced CPP was evaluated weekly. Mice showed CPP after four sessions of conditioning with 5, 10, 20 and 40 mg/kg of morphine, which lasted 0, 1, 2 and 4 weeks, respectively. In Experiment 2, after four sessions of conditioning with 40 mg/kg of morphine, the effects of four schedules of extinction differing in the time interval (2, 4, 6 or 8 weeks) between sessions were evaluated. CPP was no longer evident after 8 weeks for the groups examined each 2 or 8 wee…
The effects of morphine on the temporal structure of Wistar rat behavioral response to pain in hot-plate
2016
Rationale: The largest amount of researches on the hot-plate test was carried out using quantitative assessments. However, the evaluation of the relationships among the different elements that compose the behavioral response to pain requires different approaches. Although previous studies have provided clear information on the behavioral structure of the response, no data are available on its temporal structure. Objectives: The objective of this study was to investigate the temporal structure of the behavioral response to pain in Wistar rat tested in hot-plate and how this structure was influenced by morphine-induced analgesia. Methods: The behavior of four groups of subjects tested in hot-…
Spontaneous Cingulate High-Current Spikes Signal Normal and Pathological Pain States
2019
Prominent 7–12 Hz oscillations in frontal cortical networks in rats have been reported. However, the mechanism of generation and the physiological function of this brain rhythm have not yet been clarified. Multichannel extracellular field potentials of the ACC were recorded and analyzed using the current source density method in halothane-anesthetized rats. Spontaneous high-current spikes (HCSs) were localized in the deep part of layer II/III and upper part of layer V of the ACC. The frequency of HCSs in the ACC was 7–12 Hz, with an amplitude of 6.5 ± 0.76 mV/mm(2) and duration of 55.24 ± 2.43 ms. The power density significantly decreased (84.56 ± 6.93%, p < 0.05, t test) after pinching the…
7-Nitroindazole blocks conditioned place preference but not hyperactivity induced by morphine.
2003
The effects of 7-nitroindazole (7-NI), a neural nitric oxide synthase (nNOS) inhibitor, on spontaneous locomotor activity, morphine-induced hyperactivity, acquisition of place conditioning and morphine-induced conditioned place preference (CPP) were evaluated in male mice. In experiment 1, animals treated with 7-NI (25, 50 and 100 mg/kg), morphine (40 mg/kg) or morphine (40 mg/kg) plus 7-NI (25, 50 or 100 mg/kg) were placed in an actimeter for 3 h. In experiment 2, animals treated with the same drugs and doses were conditioned following an unbiased procedure. 7-NI did not affect the spontaneous locomotor activity or hyperactivity induced by morphine. However, the moderate and high doses of …
Switching from morphine to methadone to improve analgesia and tolerability in cancer patients: A prospective study
2001
PURPOSE: To evaluate the clinical benefits of switching from morphine to oral methadone in patients who experience poor analgesia or adverse effects from morphine. PATIENTS AND METHODS: Fifty-two consecutive cancer patients receiving oral morphine but with uncontrolled pain and/or moderate to severe opioid adverse effects were switched to oral methadone administered every 8 hours using different dose ratios. Intensity of pain and adverse effects were assessed daily, and the symptom distress score (DS) was calculated before and after switching. RESULTS: Data were analyzed for 50 patients. Switching was considered effective in 80% of the patients; results were achieved in an average of 3.65 …
Amitriptyline in neuropathic cancer pain in patients on morphine therapy: A randomized placebo-controlled, double-blind crossover study
2002
Aims and Background Amitriptyline is the most common analgesic adjuvant used in cancer patients with neuropathic pain, even though no specific studies have demonstrated a benefit. A randomized placebo-controlled, double-blind crossover study was designed to evidence the effects of amitriptyline in patients with neuropathic cancer pain. Methods Sixteen advanced cancer patients with neuropathic pain on systemic morphine therapy, no longer receiving oncologic treatment, presenting moderate pain (about 4 or more, but less than 7, on a numerical scale of 0-10) in the last week, and given a stable morphine dose in the last 2 days were admitted to the study. During the first week of study, patient…
A randomised controlled study on the use of anti-inflammatory drugs in patients with cancer pain on morphine therapy: effects on dose-escalation and …
2002
The role of non-steroidal anti-inflammatory drugs (NSAIDs) in cancer pain has been well established in the treatment of mild pain and in association with opioids in the treatment of moderate to severe pain. The aim of this study was to verify the effects of NSAIDs on morphine escalation in advanced cancer patients with pain followed-up at home and to assess the pharmacoeconomic implications. A prospective randomised controlled study was carried out in 156 consecutive advanced cancer patients with pain followed-up at home in the period December 1999-December 2000. In this group of patients, 47 were selected with pain progression after 1 week of opioid stabilisation. Patients were randomly as…