Different effects of orexin-A on AMPA receptor-mediated currents of on- and off-type ganglion cells in rat retina
会议名称：《中国神经科学学会第九届全国学术会议暨第五次会员代表大会》
会议日期：2011年
学科分类：0710[理学-生物学] 07[理学] 071006[理学-神经生物学]
关 键 词：orexin-A orexin 1 receptor AMPA receptor neurotransmission retina ganglion cells
摘 要：Objective Two novel neuropeptides,orexin-A and orexin-B,are identified as endogenous ligands of two orphan G-protein-coupled receptors:orexin 1 and orexin 2 receptors(OXR and OXR).This neuropeptide system is involved in a variety of physiological processes,such as sleep/wake regulation,feeding behaviors *** most of the mammalian suprachiasmatic nucleus(SCN) circadian clock is photoentrained by photic signals from the retina through the retinohypothalamic tract,little is known about the distribution and function of orexins in *** purpose of this study is to investigate how orexins and OXRs are expressed in the rat retina and how orexin-A modulates AMPA receptors in retinal ganglion cells(GCs).Methods Western blot analysis and immunocytochemistry were used to explore the distribution of orexins and OXRs in rat *** of orexin-A on AMPA receptor-mediated currents were investigated in freshly dissociated GCs by whole cell patchclamp recording *** By immunocytochemistry,we show that orexin-A and orexin-B are strongly expressed in horizontal,bipolar,amacrine cells(ACs) and ***,OXR immunoreactivity is observed in most of GCs and all dopaminergic ACs,as well as in both outer and inner plexiform *** contrast,no obvious OXR immunostaining is detectable in the rat *** patch-clamp whole-cell recording,we first characterized AMPA receptor-mediated currents of ***,we found that 100 nM orexin-A suppressed AMPA-induced currents in 53 out of 59 OFF-type GCs *** average,following the perfusion of 100 nM orexin-A,the AMPAinduced currents were reduced to 62.0±2.1%of control(P 0.0001).In contrast,100 nM orexin-A increased AMPAinduced currents in 11 out of 14 ON-type GCs to 153.7±8.5%of control(P 0.0001).The effects of orexin-A were completely blocked by TCS1102,an antagonist for both OXR and OXR(n = 7).In most of ON- and OFF-GCs,the effects of orexin-A were eliminated by SB334867,a selective OXR antagoni