Evidence for cocaine and methylecgonidine stimulation of M(2) muscarinic receptors in cultured human embryonic lung cells.
Evidence for cocaine and methylecgonidine stimulation of M(2) muscarinic receptors in cultured human embryonic lung cells.
复制标题
可卡因和甲基爱康定刺激培养的人胚胎肺细胞中的 M(2) 毒蕈碱受体的证据。
DOI：
10.1038/sj.bjp.0703819
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发表时间：
2001
影响因子：
7.3
通讯作者：
Morgan,JP
中科院分区：
文献类型：
--
作者：
Yang,Y;Ke,Q;Cai,J;Xiao,YF;Morgan,JP
Muscarinic cholinoceptor stimulation leads to an increase in guanylyl cyclase activity and to a decrease in adenylyl cyclase activity. This study examined the effects of cocaine and methylecgonidine (MEG) on muscarinic receptors by measurement of cyclic GMP and cyclic AMP content in cultured human embryonic lung (HEL299) cells which specifically express M2muscarinic receptors.A concentration‐dependent increase in cyclic GMP production was observed in HEL299 cells incubated with carbachol, cocaine, or MEG for 24 h. The increase in cyclic GMP content was 3.6 fold for 1 μMcarbachol (P<0.01), 3.1 fold for 1 μMcocaine (P<0.01), and 7.8 fold for 1 μMMEG (P<0.001), respectively. This increase in cyclic GMP content was significantly attenuated or abolished by the muscarinic receptor antagonist atropine or the M2blocker methoctramine.In contrast, cocaine, MEG, and carbachol produced a significant inhibition of cyclic AMP production in HEL299 cells. Compared to the control, HEL299 cells treated with 1 μMcocaine decreased cyclic AMP production by 30%. MEG and carbachol at 1 μMdecreased cyclic AMP production by 37 and 38%, respectively. Atropine or methoctramine at 1 or 10 μMsignificantly attenuated or abolished the cocaine‐induced decrease in cyclic AMP production. However, the antagonists alone had neither an effect on cyclic GMP nor cyclic AMP production. Pretreatment of HEL299 cells with pertussis toxin prevented the cocaine‐induced reduction of cyclic AMP production.Western blot analysis showed that HEL299 cells specifically express M2muscarinic receptors without detectable M1and M3. Incubation of HEL299 cells with cocaine, carbachol, and atropine did not alter the expression of M2protein levels. However, the inducible isoform of nitric oxide synthase (iNOS) was induced in the presence of cocaine or carbachol and this induction was significantly attenuated after addition of atropine or methoctramine.The present data show that cocaine and MEG significantly affect cyclic GMP and cyclic AMP production in cultured HEL299 cells. Our results also show that these effects result from the drug‐induced stimulation of M2muscarinic receptors accompanied with no alterations of receptor expression. However, the induction of iNOS by cocaine may result in the increase in cyclic GMP production.British Journal of Pharmacology(2001)132, 451–460; doi:10.1038/sj.bjp.0703819
