Résumé
A brand-new class of photoreceptors has been identified in the past 20a: intrinsically photosensitive retinal ganglion cells(ipRGC). With melanopsin as its photopigment, ipRGCs transmit light signals to non-imaging brain regions like the suprachiasmatic nucleus(SCN)and the olivary pretectal nucleus(OPN)to regulate circadian photoentrainment and pupillary light reflex; a small portion of the signals are projected to brain imaging regions like the dorsal lateral geniculate nucleus(dLGN)and superior colliculus(SC), to participate in imaging vision. There are six different ipRGC subtypes(M1～M6), each with its own morphological and physiological characteristics. In addition to receiving signaling inputs from the rods and cones, ipRGCs also regulate retinal signals through chemical and electrical synapses and play important roles in visual signaling and visual development. It has been discovered that ipRGCs are implicated in several systemic and ocular illnesses. Overall, various aspects of ipRGC are reviewed including the discovery, general physiological properties, signaling, and the relationship with disease in this work.
Résumé
Light therapy, a non-intrusive approach, is now considered as a promising new treatment method for a variety of mood disorders such as depression, bipolar disorder, postpartum depression and so on. However, the neural mechanism of light therapy to regulate emotions is still unclear, and the clinical application of light therapy and its side effects are still controversial. Light therapy regulates mood may be related to the changes of neural circuit mediated by intrinsically photosensitive retinal ganglion cells(ipRGCs), clock gene expression, circadian rhythm and sleep structure. In this paper, the treatment of mood disorders by light has been discussed, and a variety of neural circuits and molecular biological mechanisms of light therapy are introduced, meanwhile, the current situation and side effects of light therapy have been analyzed, in order to provide evidence for the application and promotion of light therapy in the treatment of mood disorders.
Résumé
Objective This study was to observe the morphology of live intrinsically photosensitive retinal ganglion cells (ipRGCs) at cellular level,and to explore their three-dimensional structure and responses to light in curved retina and the relationship with rod/cone photoreceptors.Methods ipRGCs were identified according to the enhanced green fluorescent potein (EGFP) markers.Two hundred and sixty-three ipRGCs were videoed in mouse whole-mounted retina after strengthening with Lucifer Yellow from patch clamp electrodes.The dendrites and cell bodies were analyzed according to their sublayer-specific localization in inner plexiform layer and ganglion cell layer of curved retina.The relationship with rod/cone system was reconstructed and their functions were speculated.The animal feeding and use was in accordance with the standards set by the ARVO,and the experiment was approved by the Ethic Committee for Experimental Animal of Hubei University of Science and Technology.Results The ipRGCs had strictly sublayer-specific localization in three sublayers of retinal inner plexiform layer.Each sublayer occupies full retina and form photosensitive surface,without any intermediate photosensitive dentric distribution between sublayers.Each ipRGC had randomly dentric distributions among the three sublayer curves,without the specific ON/OFF stratification.The photosensitive sublayers had absolutely perpendicular assignment related to cone/rod photoreceptors.The expression of melanopsin and spike-producing Ca2+/Na+ channels were randomly distributed in M1,M2 and M3 cells.M4 and M5 cells shared the characteristic properties of conventional ganglion cells.Conclusions In contrast to the rod/cone photoreceptors,ipRGCs form multiple-sublayer photosensitive curved surface,which are perpendicular to rod/cone photoreceptors,their photosensitive melanopsin and intrinsic spike-producing channels randomly occupy these specific sublayers,which suggest their distinct functions from rod/cone photoreceptors.
Résumé
ObJeetive To report a simple and efficient method to label two different types of retinal ganglion cells (RGCs) in mouse retina.Methods Eyeballs were harvested from normal adult C57 BL/6 J mouse,the retinas were isolated,four radial cuts were done,the retinas were pasted on the nitrocellulose membrane with the ganglion cell layer upturned.The immunofluorescence double staining and laser confocal nmicroscope was used to reveal conventional retinal ganglion cells and intrinsically photosensitive retinal ganglion cells (ipRGCs) using Brn3a and Melanopsin.Results The double staining results of whole mount retina showed that conventional RGCs and melanopsin immunopositive ipRGCs had a complementary distribution in mouse retina,these two subtypes of RGCs were predominantly present in the ganglion cell layer.The numbers of ipRGCs was just about 1％-2％ of conventional RGCs,and the axons of ipRGCs toward the direction of the optic disc,several dendrites toward the inner plaximem layer.Conclusion The immunofluorescence double staining of whole mount retina is a simple,stable and efficient method to label two different types of mouse RGCs.