Search results for "SENSITIZATION"

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…

On the peptidergic hypothesis for non-adrenergic non-cholinergic innervation in the rat duodenum

1992

1. The nature of the non-adrenergic, non-cholinergic (NANC) transmitter was studied in vitro in the rat duodenum, by use of an isometric-isovolumic preparation. 2. Electrical field stimulation (EFS) induced a tetrodotoxin (TTX)-sensitive fall both in luminal pressure and in isometric tension. 3. Neurotensin (NT) induced TTX-insensitive inhibitory responses similar to those induced by EFS. Vasoactive intestinal peptide (VIP) caused a delayed, slow, concentration-dependent, TTX-insensitive inhibitory effect, detected only by a change in luminal pressure. 4. alpha-chymotrypsin prevented the NT- and VIP-induced inhibitory effects and antagonized the response to EFS. 5. Apamin antagonized the EF…

Effects of sensitization on vasoactive intestinal polypeptide-induced relaxation and its concentration and binding in guinea-pig airways.

1993

We investigated the relaxant effect of vasoactive intestinal polypeptide (VIP) in trachea and lung parenchyma from normal and sensitized guinea-pigs. A technique by which drug access was restricted to either the mucosal or the adventitial surface of tracheal rings was used. In intact trachea, concentration-response curves for VIP entering from the mucosal surface (pD2 = 6.61 +/- 0.06) were displaced to the right compared with those for adventitial entry (pD2 = 6.78 +/- 0.04). Epithelium removal produced a leftward shift (approximately 2.8-fold) in the mucosal VIP concentration-response curve. Sensitization did not alter the responsiveness (maximal effect) or sensitivity (pD2 values) of trac…

Pharmacological characterisation of a new model of antigen-induced pulmonary late-phase reaction in the conscious guinea pig which uses additional po…

1996

The aim of the present study was to develop a new model of allergic late-phase reaction in the airways of conscious guinea pigs (GPs) and to characterise it by pharmacological intervention. GPs were pretreated with cyclophosphamide and sensitized with ovalbumin (OA) in Al(OH)3. Weekly inhalations of polymyxin B were performed before and during sensitization and continued throughout the study period. Under cover of 10 mg/kg i.p. mepyramine all GPs still exhibited a pronounced immediate reaction (IR), peaking during the first 15 min after OA. Nine out of 15 GPs demonstrated, during screening, a reproducible (twice) second phase (late phase reaction (LPR)] of decreased airflow and tidal volume…

Systematic review: progression of beryllium sensitization to chronic beryllium disease

2012

BACKGROUND The relevance of beryllium sensitization testing for occupational health practice and prevention is unclear. AIMS To analyse the natural course of beryllium sensitization and clarify the prognosis following cessation of exposure among sensitized workers. METHODS An electronic literature search was conducted in PubMed, Embase, Toxline and Cochrane databases supplemented by a manual search. Data abstraction and study quality assessment with adapted guideline checklists were performed independently by three reviewers. Seven studies met the eligibility criteria and were included in the systematic review; however, six of the seven studies were of low methodological quality. RESULTS A …

Different skin prick test sensitization patterns do not influence the response to omalizumab in severe asthma

2017

Fatal Anaphylactic Shock Ceftriaxone-Induced in a 4-Year-Old Child

2014

One of the most used cephalosporin in clinical practice is ceftriaxone. Anaphylaxis due to the administration of ceftriaxone is considered a rare event. Here, we report a case of fatal anaphylactic shock after the administration of ceftriaxone in a child who had tolerated the drug in past exposures. The allergic pathogenesis is sustained by the clinical data (short time between the inoculation of the drug and the onset of the symptoms; past exposure to the same molecule and probable sensitization) and the postmortem examination findings (polivisceral congestion and intense eosinophilia found in the histological examination).

Mechanisms of DNA damage by photoexcited 9-methyl-β-carbolines

2013

It has been well documented that β-carboline alkaloids, particularly the 9-methyl derivatives, are efficient photosensitizers. However, structure–activity relationships are missing and the photochemical mechanisms involved in the DNA photodamage still remain unknown. In the present work, we examined the capability of three 9-methyl-β-carbolines (9-methyl-norharmane, 9-methyl-harmane and 9-methylharmine) to induce DNA damage upon UVA excitation at physiological pH. The type and extent of the damage was analyzed together with the photophysical and binding properties of the β-carboline derivatives investigated. The results indicate that even at neutral pH most of the DNA damage is generated fr…

Role of AMPA receptor desensitization in short term depression : lessons from retinogeniculate synapses

2021

Repetitive synapse activity induces various forms of short-term plasticity. The role of presynaptic mechanisms such as residual Ca2+ and vesicle depletion in short-term facilitation and short-term depression is well established. On the other hand, the contribution of postsynaptic mechanisms such as receptor desensitization and saturation to short-term plasticity is less well known and often ignored. In this review, I will describe short-term plasticity in retinogeniculate synapses of relay neurons of the dorsal lateral geniculate nucleus (dLGN) to exemplify the synaptic properties that facilitate the contribution of AMPA receptor desensitization to short-term plasticity. These include high …

Desensitization is a property of the cholinergic binding region of the nicotinic acetylcholine receptor, not of the receptor-integral ion channel

1991

AbstractThe reversible acetylcholine esterase inhibitor (−)-physostigmine (eserine) is the prototype of a new class of nicotinic acetylcholine receptor (nAChR) activating ligands: it induces cation fluxes into nAChR-rich membrane vesicles from Torpedo marmorala electric tissue even under conditions of antagonist blocked acetylcholine binding sites (Okonjo, Kuhlmann, Maclicke, Neuron, in press). This suggests that eserine exerts its channel-activating property via binding sites at the nAChR separate from those of the natural transmitter. We now report that eserine can activate the channel even when the receptor has been preincubated (desensitized) with elevated concentrations of acetylcholin…