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27 mars 2012

La newsletter de stop-tabac: les sujets clés de l?actualité mondiale sur le tabagisme

Sélection réalisée par Jean-François Etter

Le 27 mars 2012

The high-affinity nAChR partial agonists varenicline and sazetidine-A exhibit reinforcing properties in rats.
- Youtube: vidéo sur les risques du tabac
- Free, online CME program
- Chattez avec un médecin tabacologue

The high-affinity nAChR partial agonists varenicline and sazetidine-A exhibit reinforcing properties in rats.

Varenicline (Chantix, Champix) is a nicotinic acetylcholine receptor (nAChR) partial agonist clinically approved for smoking cessation, yet its potential abuse liability properties have not been fully characterized. The nAChR ligand sazetidine-A has been reported as a selective full or partial agonist at ?4?2* nAChR subtypes in in vitro studies. In the present studies, varenicline, sazetidine-A and nicotine exhibited inverted U-shaped dose-response functions under fixed-ratio (peak responding at 30, 60 and 10-30 ?g/kg/inf, respectively) or progressive-ratio (peak responding at 30-60, 30-100 and 30 ?g/kg/inf, respectively) schedules in rats trained to self-administer nicotine. Varenicline (ED(50) 0.2 mg/kg) and sazetidine-A (ED(50) 0.44 mg/kg) fully substituted for nicotine (ED(50) 0.09 mg/kg) in rats trained to discriminate nicotine (0.4 mg/kg, i.p.) from saline. The reinforcing and discriminative stimulus (DS) properties of sazetidine-A, varenicline and nicotine were attenuated by acute pretreatment with the non-selective neuronal non-competitive nAChR antagonist mecamylamine or the ?4* nAChR-selective antagonist dihydro-?-erythroidine, but not by the ?7 nAChR subtype antagonist methyllycaconitine. Drug-naïve rats acquired stable self-administration of varenicline (30 ?g/kg/inf), and sazetidine-A (60 ?g/kg/inf), at doses that supported peak responding under a fixed-ratio 3 schedule in nicotine-trained rats. Nonetheless, self-administration and re-acquisition of varenicline and sazetidine-A were less robust than nicotine. Thus, partial activation of ?4?2* nAChRs by varenicline or sazetidine-A is sufficient to mimic the DS and reinforcing properties of nicotine in nicotine-experienced rats, although the reinforcing properties of partial agonists are diminished in nicotine-naïve rats. Future studies should assess nicotine withdrawal measures in animals chronically exposed to varenicline or sazetidine-A.

Prog Neuropsychopharmacol Biol Psychiatry. 2010 Dec 1;34(8):1455-64. Epub 2010 Aug 11. (03 05 2011)
(27 03 2012)

Youtube: vidéo sur les risques du tabac

Ames sensibles s'abstenir:
http://www.youtube.com/watch?v=0PdjqGYjIJo (04 05 2011)
(27 03 2012)

Free, online CME program

The University of Wisconsin School of Medicine and Public Health is pleased to announce the availability of a free, online, one-hour CME program on treating tobacco use and dependence.

Participants will learn best evidence-based practices-such as what combinations of counseling and medications are most effective-culled from the U.S. Public Health Service Clinical Practice Guideline: Treating Tobacco Use and Dependence (2008).

Simply log on to: http://cme.medscape.com/viewprogram/17710

For more information, see CME flyer: http://www.ctri.wisc.edu/HC.Providers/CMEflyer.pdf (12 05 2011)
(27 03 2012)

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