Abstract
For electrophysiological studies of retinal ganglion cells (RGCs) in vivo, intraocular recording of RGC activity was well established in large mammals, such as cats and monkeys. However, the intraocular recording is technically difficult to be applied to rodents, because of their small eyeballs with large lenses. We here developed and validated a new method for in vivo recording of rat RGCs. Anesthetized adult rats underwent extracapuslar lensectomy and implantation of a imitation lens made from agarose. Thus, a tungsten microelectrode was easily inserted into the retina through the imitation lens for recording spike discharge of RGCs. A reference electrode was also inserted and situated in the lens. During the experiment, the eyeground was sporadically inspected for retinal detachment and/or ischemia. Retinas were able to keep up intact condition for several hours. Both single- and multi-unit activities of RGC were successfully recorded from not only the central but peripheral retinas with the electrodes which were three-dimensional micro-positioned. Spontaneous activities and responses to light stimulation of RGCs were recorded, in which the spike amplitudes of RGC activities were 90-400 μV. This method may be useful for in vivo electrophysiological studies of local impairments and recovery in the rat retinal function by various experimental manipulations, such as electrical stimulation, gene therapy, transplantation of stem cells and retinal prosthesis. Moreover, the technique might be applicable to studies in mice. [J Physiol Sci. 2007;57 Suppl:S106]
