Search results for "Narcotic antagonist"
showing 10 items of 34 documents
The gamma(2)-MSH peptide mediates a central analgesic effect via a GABA-ergic mechanism that is independent from activation of melanocortin receptors.
2001
Using the latency for tail-flick after thermal stimulation we have assessed the effects of alpha-, gamma(1)- and gamma(2)-MSH on nociceptive threshold in the mice. Intracisternal injections of gamma(2)-MSH induced a distinct analgesia, while gamma(1)-MSH in the same doses gave only a minor analgesia. Intracisternal alpha-MSH instead gave a short-term hyperalgesia. The effect of gamma(2)-MSH was not blocked by any of the MC(4)/MC(3)receptor antagonist HS014, naloxone or by the prior intracisternal administrations of gamma(1)-MSH. However, the gamma(2)-MSH analgesic response was completely attenuated by treating animals with the GABA(A)antagonist bicuculline. The gamma(2)-MSH analgesic effect…
Effects of endotoxin on neurally-mediated gastric acid secretion in the rat.
1998
Abstract The effects of a peripheral administration of E. coli endotoxin on neurally-mediated gastric acid secretion and the role of endogenous opioids or PAF receptors in endotoxin effects have been evaluated in the continuously perfused stomach of the anaesthetized rat. Gastric acid secretion stimulated by distension (20 cm H2O) was reduced dose-dependently by single intravenous bolus injection of endotoxin (0.1–10 μg kg−1). Doses of 5 μg kg−1 induced a peak reduction of distension-stimulated acid output and significantly reduced the secretory response induced by an intravenous bolus of 2-deoxy-d-glucose (150 mg kg−1). This dose of endotoxin did not significantly modify mean systemic arte…
Patients’ experiences of continued treatment with extended-release naltrexone: a Norwegian qualitative study
2022
Abstract Background The opioid antagonist extended-release naltrexone (XR-NTX) in the treatment of opioid use disorder (OUD) is effective in terms of safety, abstinence from opioid use and retention in treatment. However, it is unclear how patients experience and adjust to losing the possibility of achieving an opioid effect. This qualitative study is the first to explore how people with opioid dependence experience XR-NTX treatment, focusing on the process of treatment over time. Methods Using a purposive sampling strategy, semi-structured interviews were undertaken with 19 persons with opioid use disorder (15 men, four women, 22–55 years of age) participating in a clinical trial of XR-NTX…
Diffusion of naltrexone across reconstituted human oral epithelium and histomorphological features
2006
Abstract In transbuccal absorption a major limitation could be the low permeability of the mucosa which implies low drug bioavailability. The ability of naltrexone hydrochloride (NLX) to penetrate a resembling histologically human buccal mucosa was assessed and the occurrence of any histomorphological changes observed. We used reconstituted human oral (RHO) non-keratinised epithelium as mucosal section and a Transwell diffusion cells system as bicompartmental model. Buccal permeation was expressed in terms of drug flux ( J s ) and permeability coefficients ( K p ). Data were collected using both artificial and natural human saliva. The main finding was that RHO does not restrain NLX permeat…
The future: critical knowledge about anti-itch therapy.
2005
: Itch is an extremely frequent and enervating symptom of many diseases. Current anti-itch therapy, which is based almost exclusively on an “immunocentric” viewpoint, is often unsatisfactory. Recent studies show that this symptom is in fact the result of a complex interplay among skin, nervous system, endocrine system, and immune system. This explains the frequent failure of therapeutic strategies focused only on a single factor and suggests the usefulness of a polypharmacologic symptomatic treatment, designed on a case-by-case basis as a result of a multidisciplinary approach. We discuss the perspectives of anti-itch therapy in light of the new pathogenetic and pharmacologic acquisitions.
Memantine presents different effects from MK-801 in motivational and physical signs of morphine withdrawal
2003
Adaptive changes in neural systems due to chronic opiate exposure are related to the neural plasticity phenomenon, NMDA receptors being implicated in these processes, e.g. tolerance, dependence or withdrawal. In this work, we investigated the effect of two non-competitive NMDA antagonists, memantine and MK-801, in motivational (Conditioned Place Aversion paradigm, CPA) and physical aspects of morphine withdrawal. After the induction of morphine dependence, animals in which the CPA was studied, received memantine (5 and 10 mg/kg) or MK-801 (0.3-0.006 mg/kg) either during the acquisition (conditioning) or expression (test) phase of this procedure. Both drugs were capable of inhibiting conditi…
Sensitivity of neuronal nicotinic acetylcholine receptors to the opiate antagonists naltrexone and naloxone: receptor blockade and up-regulation
2003
In HEK293 cells stably expressing alpha4beta2 nAChRs, naltrexone, but not naloxone, blocked alpha4beta2 nAChRs via an open-channel blocking mechanism. In primary hippocampal cultures, naltrexone inhibited alpha7 nAChRs up-regulated by nicotine, and in organotypic hippocampal cultures naltrexone caused a time-dependent up-regulation of functional alpha7 nAChRs that was detected after removal of the drug. These results indicate that naltrexone could be used as a smoking cessation aid.
Environment associated with morphine and experience of aggression modulate behaviors of postdependent mice
2002
Contexts associated with drug use can acquire secondary reinforcing properties. Furthermore, context-specific withdrawal has been observed to reflect a relatively long-lasting learned response. The aim of this study was to evaluate the effect of the environment paired with morphine after 15 days of abstinence. In the first experiment, isolated male mice received saline or morphine either in their home cage or in the distinctive environment, performing two agonistic encounters in the distinctive environment during spontaneous withdrawal. Similar groups were assigned but without aggression encounters during withdrawal. In the second experiment, animals received saline or morphine as previousl…
High dose naloxone does not improve cerebral or myocardial blood flow during cardiopulmonary resuscitation in pigs
1997
In a prospective, randomized, placebo-controlled, double-blind trial we tested the hypothesis that naloxone given during cardiopulmonary resuscitation (CPR) enhances cerebral and myocardial blood flow. Twenty-one anesthetized, normoventilated pigs were instrumented for measurements of right atrial and aortic pressures, and regional organ blood flow (radiolabeled microspheres). After 5 min of untreated fibrillatory arrest, CPR was commenced using a pneumatic chest compressor/ventilator. With onset of CPR, an i.v. bolus of 40 micrograms/kg b.w. of epinephrine was given, followed by an infusion of 0.4 micrograms/kg per min. After 5 min of CPR, either naloxone, 10 mg/kg b.w. (group N, n = 11) o…
The Endogenous Opioid System Is Not Involved in Modulation of Opioid-Induced Hyperalgesia
2009
Abstract Some recent studies suggested a role of the endogenous opioid system in modulating opioid-induced hyperalgesia (OIH). In order to test this hypothesis, we conducted a prospective randomized, placebo-controlled, 2-way crossover study in healthy human volunteers. We utilized a well-established model of inducing OIH after a brief exposure to the μ-opioid agonist remifentanil using intradermal electrical stimulation. Patients were exposed to a randomized 90-minute infusion of remifentanil or saline placebo during 2 separate occasions. Development of OIH was quantified using changes in the average radius of the area of secondary hyperalgesia generated by electrical pain stimulation. A 2…