Search results for "Morphine"
showing 10 items of 145 documents
Sensitization to the rewarding effects of morphine depends on dopamine
2005
The influence of dopamine (DA) on sensitization to the rewarding effects of morphine was evaluated. The effects of pre-treatment with saline or morphine plus naloxone, CGS 10746B, haloperidol, SCH 23390 and raclopride, on the place conditioning induced by 2 mg/kg morphine were evaluated. This dose was ineffective in saline pre-treated animals but induced a clear conditioned place preference in mice pre-treated with morphine, CGS 10746B or haloperidol. Conversely, animals pre-treated with morphine plus naloxone, CGS 10746B, SCH 23390, raclopride and the high dose of haloperidol did not acquire place preference. Our results demonstrated that DA release and subsequent DA D1 and D2 receptor act…
Modulation by peripheral opioids of basal and distension-stimulated gastric acid secretion in the rat.
1992
1. The influence of opioids in modulating gastric acid secretory responses has been investigated in the continuously perfused stomach of the anaesthetized rat. 2. Intravenous administration of morphine (0.75-3 mg kg-1) or the peripherally acting enkephalin analogue, BW443C (0.75-3 mg kg-1), substantially augmented acid secretion in basal conditions. These effects were significantly inhibited by the opioid antagonists naloxone (1 mg kg-1) and the peripherally acting N-methylnalorphine (2 mg kg-1). When administered alone, neither opioid antagonist influenced basal acid output. 3. Acid secretory responses to different levels of gastric distension (5-20 cmH2O) were significantly and dose-depen…
Relapse prevention in alcoholics by cigarette smoking? Involvement of nicotinic-dopaminergic mechanisms.
2001
Because of a controversial view on the role of smoking in the recovery process of alcoholism, outcome data obtained for alcoholics who had been included in a long-term clinical trial with a putative anticraving drug were analyzed. To avoid unknown interactions between the drug under study and smoking behavior, only placebo-treated patients were evaluated in this investigation. After 12 months of rehabilitation, there was no significant difference regarding abstinence rate between 48 smoking alcoholics (who reported that they smoked 32 cigarettes on average per day) and 15 nonsmoking alcoholics (33% vs. 20%). However, smokers tended to be abstinent longer than nonsmokers (173 vs. 114 days; P…
Presynaptic effects of scopolamine, oxotremorine, noradrenaline and morphine on [3H] acetylcholine release from the myenteric plexus at different sti…
1987
The inhibition by three modulators (oxotremorine, noradrenaline, morphine) of acetylcholine release from the myenteric plexus preincubated with [3H]choline was investigated at different stimulation frequencies and calcium concentrations. Moreover, [3H]acetylcholine release evoked by a low (0.1 Hz) or a high (10 Hz) stimulation rate was investigated at different calcium concentrations either in the absence or presence of scopolamine. A reduced calcium concentration (0.6 mmol/l) inhibited acetylcholine release more at 0.1 Hz (74% +/- 3%) than at 10 Hz (44% +/- 8%). Scopolamine enhanced the stimulated acetylcholine release at a calcium concentration of 1.8 mmol/l. At calcium concentrations hig…
The inhibition by dopamine of cholinergic transmission in the isolated guinea-pig ileum. Mediation through alpha-adrenoceptors.
1982
1. Segments of the guinea-pig ileum were incubated in Tyrode's solution containing 3 μM propranolol. Dopamine, like noradrenaline and clonidine, inhibited the twitch response to field stimulation. The inhibitory action of dopamine remained unchanged in the presence of the dopamine uptake inhibitor nomifensine (1 μM). Tissue from reserpine-pretreated amimals was insensitive to tyramine but the response to dopamine was not affected. It is, therefore, assumed that the effect of dopamine is due to a direct receptor stimulation and not to the release of noradrenaline. 2. The inhibitory action of dopamine was not antagonized by the dopamine receptor antagonists cis-flupenthixol, pimozide or dompe…
Effects of CGS 10746B on hyperactivity and place preference induced by morphine
2001
The effects of CGS 10746B, a dopamine release inhibitor, on spontaneous locomotor activity, morphine-induced hyperactivity, acquisition of conditioned place paradigm and morphine-induced conditioned place preference (CPP) was evaluated in male mice. In experiment 1, animals treated with CGS 10746B (0.5, 1, 2, 4, 8, 16, 24 and 32 mg/kg), morphine (40 mg/kg) or morphine (40 mg/kg) plus CGS 10746B (0.5, 1, 2, 4, 8, 16, 24 and 32 mg/kg) were placed in an actimeter during a period of 90 min. In experiment 2, animals treated with CGS 10746B (0.5, 1, 3 and 10 mg/kg), morphine (40 mg/kg) or morphine (40 mg/kg) plus CGS 10746B (0.5, 1, 3 and 10 mg/kg) were conditioned following a procedure unbiased …
EFFECTS OF 4-AMINOPYRIDINE ON ACETYLCHOLINE OUTPUT FROM THE CEREBRAL CORTEX OF THE RAT in vivo
1982
Abstract 1 The effects of 4-aminopyridine (4AP) on the output of acetylcholine (ACh) from the cerebral cortex were investigated in unanaesthetized freely moving rats and in anaesthetized rats by means of the `cup technique'. ACh was determined by bioassay on the dorsal muscle of the leech. 2 In unanaesthetized rats intraperitoneal injection of 4AP (3 mg/kg) had no effect on the cortical output of ACh. 3 After injection of morphine (10 mg/kg s.c.), which depressed the spontaneous output of ACh, 4AP increased the cortical output to a level significantly higher than that determined before morphine injection. 4 In rats anaesthetized with either urethane or pentobarbitone, drugs known to decreas…
Opioid switching in patients with advanced cancer followed at home. A retrospective analysis.
2013
Abstract CONTEXT: Opioid switching has been found to improve opioid responsiveness in different conditions. However, data on opioid switching performed at home are almost nonexistent, despite the fact that most patients are followed at home. OBJECTIVES: The aim of this retrospective survey was to determine frequency, indications, usefulness, and safety of opioid switching when treating advanced cancer-related pain in patients followed at home. METHODS: A retrospective review of data from patients with advanced cancer followed at home by three home care teams for a period of two years was performed. Patients who had their opioids switched were selected. Reasons for switching opioid doses and…
Equipotent doses to switch from high doses of opioids to transdermal buprenorphine.
2008
INTRODUCTION: The aim of this study was to evaluate the equianalgesic ratio of transdermal buprenorphine (TD BUP) with oral morphine and TD fentanyl in a sample of consecutive cancer patients receiving stable doses of 120-240 mg of oral morphine or 50-100 microg of TD fentanyl, reporting adequate pain and symptom control. MATERIALS, METHODS, AND RESULTS: Patients receiving daily stable doses of opioids for more than 6 days, with no more than two doses of oral morphine (20 and 40 mg, respectively) as needed, were switched to TD BUP using a fentanyl-BUP ratio of 0.6:0.8 and an oral morphine-BUP ratio of 70:1. Opioid doses, pain and symptom intensity, global satisfaction, and number of breakth…
Possible involvement of nitric oxide in morphine-induced miosis and reduction of intraocular pressure in rabbits.
2006
The role of μ3 opioid receptors in morphine-induced intraocular pressure (IOP) lowering effect and miosis was evaluated in conscious, dark-adapted New Zealand white (NZW) rabbits using a masked-design study. IOP and pupil diameter (PD) measurements were taken at just before and 0.5, 1, 2, 4, 6 h after monolateral instillation of morphine (10, 50 and 100 μg/30 μl) as compared to vehicle administered in the contralateral eye. Morphine-induced ocular effects were challenged by a pre-treatment with the non-selective opioid receptor antagonist, naloxone (100 μg/30 μl), the nitric oxide synthase inhibitor, Nω-nitro-l-arginine methyl ester (l-NAME, 1%, 30 μl), or the non-selective μ3 opioid recept…