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.
نویسندگان
چکیده
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.
منابع مشابه
Bupropion Inhibits Nicotine-Evoked [H]Overflow from Rat Striatal Slices Preloaded with [H]Dopamine and from Rat Hippocampal Slices Preloaded with [H]Norepinephrine
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 3 2, 3 4, and 4 2 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes or established cell lines. The present study evaluated bupropion-induced inhibition of nativ...
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Previous results from our laboratory demonstrated that S(-)nornicotine, a major tobacco alkaloid and an active nicotine metabolite present in the CNS, increases dopamine release from rat striatal slices in a concentration-dependent and calcium-dependent manner. The present study determined if S(-)nornicotine-evoked dopamine release was the result of nicotinic receptor stimulation. Stereoselecti...
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Previous results from our laboratory demonstrated that S(-)nornicotine, a major tobacco alkaloid and an active nicotine metabolite present in the CNS, increases dopamine release from rat striatal slices in a concentration-dependent and calcium-dependent manner. The present study determined if S(-)nornicotine-evoked dopamine release was the result of nicotinic receptor stimulation. Stereoselecti...
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ورودعنوان ژورنال:
- The Journal of pharmacology and experimental therapeutics
دوره 302 3 شماره
صفحات -
تاریخ انتشار 2002