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Suppression of nicotinic ACh receptors--mediated currents by activation of Eph/Ephrin--B1 signaling involves Src tyrosine kinase and mitogen--activated protein kinase in ciliary ganglion neurons

Xia Yuanpeng, Hu Bo, Zhou Yunan, Mao Ling, Dai Ruolian, Dong Liping

Department of Neurology,Union Hospital,Tongji Medical College,Huazhong University of Science and Technology.Wuhan 430022,Hubei

Abstract

Recent studies showed that Eph/Ephrin tyrosine kinase family plays an important role in the development and functional maintenance of the nervous system, but its function in the sympathetic nervous system is still obscure. In the present study, we examined the effect of Eph/Ephrin-B1 signaling on the whole-cell currents mediated by either #alpha#7 or #alpha#3-nicotinic acetylcholine receptors (nAChRs) in acutly dissociated ciliary ganglion (CG) neurons. Firstly, we detected the effect of Ephrin-B1 on nAChRs currents. The neurons were randomly divided into control group, Ephrin-B1Fc-treated group that was stimulated by recombinant Ephrin-B1Fc, IgG-treated group, and Ephrin-B1-treated group. Secondly, we studied the regulatory mechanism of Ephrin-B1Fc on nAChRs currents. The neurons were randomly divided into control group, Ephrin-B1Fc-treated group, PP2 (inhibitor of Src tyrosine kinase) or PD98095 (antagonist of mitogen-activated protein kinase)-treated group, Ephrin-B1Fc + PP2 or PD98095-treated group. The results showed that there was no significant difference between the currents in control group, IgG-treated group and Ephrin-B1-treated group, but Ephrin-B1Fc significantly suppressed both #alpha#3-nAChRs and #alpha#7-nAChRs-mediated currents (P=0.002, P=0.003). Pretreatment with PP2 or PD98095 could partially rescue the Ephrin-B1Fc-induced suppression of currents mediated by #alpha#3-nAChRs or #alpha#7-nAChRs respectively. These results suggest that the Eph/Ephrin-B1 signaling may inhibit #alpha#3-nAChRs and #alpha#7-nAChRs-mediated currents on CG neurons, involving Src tyrosine kinase and mitogen-activated protein kinase signaling in the regulation of sympathetic nervous system.

Key words: #alpha#3-nAChRs;#alpha#7-nAChRs;Eph/Ephrin-B1;mitogen-activated protein kinase;Src tyrosine kinase

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Citing This Article：

Xia Yuanpeng, Hu Bo, Zhou Yunan, Mao Ling, Dai Ruolian, Dong Liping. Suppression of nicotinic ACh receptors--mediated currents by activation of Eph/Ephrin--B1 signaling involves Src tyrosine kinase and mitogen--activated protein kinase in ciliary ganglion neurons. Acta Physiol Sin 2008; 60 (4): 462-468 (in Chinese with English abstract).