Drugs online research references
J Pharmacol Exp Ther. 2002 Sep;302(3):1113-22.
Bupropion inhibits nicotine-evoked [(3)H]overflow from rat striatal slices preloaded with [(3)H]dopamine and from rat hippocampal slices preloaded with [(3)H]norepinephrine.
Miller DK, Sumithran SP, Dwoskin LP.
College of Pharmacy, University of Kentucky, Lexington, KY 40536-0082, USA.
Bupropion, an efficacious antidepressant and smoking cessation agent, inhibits dopamine and norepinephrine transporters (DAT and NET, respectively). Recently, bupropion has been reported to noncompetitively inhibit alpha3beta2, alpha3beta4, and alpha4beta2 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes or established cell lines. The present study evaluated bupropion-induced inhibition of native alpha3beta2* and alpha3beta4* nAChRs using functional neurotransmitter release assays, nicotine-evoked [(3)H]overflow from superfused rat striatal slices preloaded with [(3)H]dopamine ([(3)H]DA), and nicotine-evoked [(3)H]overflow from hippocampal slices preloaded with [(3)H]norepinephrine ([(3)H]NE). The mechanism of inhibition was evaluated using Schild analysis. To eliminate the interaction of bupropion with DAT or NET, nomifensine or desipramine, respectively, was included in the superfusion buffer. A high bupropion concentration (100 microM) elicited intrinsic activity in the [(3)H]DA release assay. However, none of the concentrations (1 nM-100 microM) examined evoked [(3)H]NE overflow and, thus, were without intrinsic activity in this assay. Moreover, bupropion inhibited both nicotine-evoked [(3)H]DA overflow (IC(50) = 1.27 microM) and nicotine-evoked [(3)H]NE overflow (IC(50) = 323 nM) at bupropion concentrations well below those eliciting intrinsic activity. Results from Schild analyses suggest that bupropion competitively inhibits nicotine-evoked [(3)H]DA overflow, whereas evidence for receptor reserve was obtained upon assessment of bupropion inhibition of nicotine-evoked [(3)H]NE overflow. Thus, bupropion acts as an antagonist at alpha3beta2* and alpha3beta4* nAChRs in rat striatum and hippocampus, respectively, across the same concentration range that inhibits DAT and NET function. The combination of nAChR and transporter inhibition produced by bupropion may contribute to its clinical efficacy as a smoking cessation agent.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12183670&dopt=Abstract
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saludalia.com
Smoking and depression are related. Bupropion, the first non-nicotinic drug that is an effective treatment in smoking cessation, is a tricyclic antidepressant that inhibits neuronal uptake of serotonin, dopamine and norepinephrine in the thalamic nuclei.Objective: To assess if certain personality factors (anxiety or depression) might predict the efficacy of bupropion for smoking cessation.Method: The study was carried out in two smoking cessation clinics in Madrid and Barcelona. Fifty patients (21 men) declaring the desire to quit smoking were enrolled. Their mean age was 43.6 years (SD 8.75). The patients were treated with 300 mg of bupropion per day for one month and expired CO was monitored for 6 months. Personality factors were assessed on a hospital anxiety and depression scale (HADS). We evaluated whether there was a significant difference in HADS scores for patients who were still not smoking after 6 months and those who had not managed to quit.Results: The 50 patients were smokers of a mean 39 packs per year (SD 17.82) and had mean scores of 7.4 (SD 4.15) for anxiety and 5.8 (SD 3.93) for depression. Four patients (8%) were unable to complete the study. After one month, 28% of the patients smoked, after 3 months 56% smoked and after 6 months 58% still smoked. The patients who smoked during the first month had higher depression scores than did the non-smokers (p = 0.03). After 3 and 6 months the patients who had managed to continue not smoking were those who had higher anxiety scores than did those who still smoked (p = 0.0052 at 3 months and p = 0.017 at 6 months).Conclusion: Patients who responded better to treatment with bupropion after 6 months of follow-up were those with higher anxiety scores on the HADS. Depression levels influenced outcome only during the first month.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12199915&dopt=Abstract
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neuro.mu-luebeck.de
Modulation of the dopamine (DA) transporter inhibitor GBR-12909 effect on DA release by protein kinases and protein phosphatases was studied in slices of the rat caudate nucleus measuring DA outflow in the superfusate of static chambers. Activation of protein kinase A and C markedly enhanced the effect of GBR-12909, whereas protein kinase inhibition by H7 reduced the GBR-12909 effect. Inhibition of protein phosphatases (PPP) 1 and 2A by okadaic acid did not modify basal outflow of DA. However, after the addition of okadaic acid a dramatic and biphasic effect was found when DA outflow was enhanced by GBR-12909. Inhibition of PPP 2A enhanced extracellular DA levels, while inhibition of PPP 1 and 2A completely abolished the effect of GBR-12909. In contrast to tetrodotoxin, the voltage-activated calcium channel blocker omega-conotoxin MVIIC inhibited GBR-12909 effects on DA outflow. Additionally, in aCSF devoid of calcium GBR-12909 did not increase DA liberation. These results suggest a complex and strong influence of phosphorylation on GBR-12909 effects on calcium channel-dependent DA outflow at low-affinity piperazine binding sites in slices of the rat caudate nucleus in vitro. Copyright 2002 Wiley-Liss, Inc.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12211084&dopt=Abstract
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