Purchase this article with an account.
Timothy Sexton, Russell Van Gelder; ipRGC light response characteristics change from post-natal to adult primarily between P8 and P15 in mice. Invest. Ophthalmol. Vis. Sci. 2013;54(15):306.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The extent and timing of development of intrinsic light sensitivity in ganglion cells has not been well described. Here, we compare light response dynamics and bleaching/adaptation of intrinsically photosensitive retinal ganglion cells (ipRGC) for three developmental time points in the mouse: P8, P15, and P30
Isolated retinas from mice at or near P8, P15 and P30, were recorded ganglion cell-side down on a multi-electrode array (MEA) while perfused with carbogen-bubbled Ames buffer at 3 ml/min with nicotinic and glutamatergic blockers (10 nM epibatidine, 10 μM DNQX, 20 μM AP-4, 50 μM AP-5) for P8-P10 retinas and glutamatergic blockers (80 μM CNQX, 100 μM AP-4, 200 μM AP-5) for all others. ipRGCs were illuminated with a xenon light filtered through a 480 nm bandpass filter at 3.98 x 1013 photon cm-2 s-1. For short-term bleaching/adaptation, retinas were exposed to a 1-min light stimulus followed by a 1-min light test with time intervals of 1-10 minutes between. Response dynamics were assessed from the initial light exposure of each retina from these experiments. For long-term bleaching/adaptation, retinas were exposed to a 1-hr continuous light, allowed to recover 10-min, and then assessed for light response every 10-min for 1-hr.
Response dynamics to a 1-min light stimulus changed with increasing age. On-latency increased (medians of P8=7 sec, P15=10 sec, P30=10.5 sec). Maximal firing rate decreased (medians of P8=20 Hz, P15=16 Hz, P30=12 Hz). Off-latency decreased substantially (medians of P8=62 sec, P15=11 sec, P30=9.5 sec). The extent of adaptation/bleaching from a 1-min light stimulus also changed. ipRGCs from P8 animals showed a decreased response of ~10% after a 1-min recovery period, which took 6-min to return to pre-exposure levels. A larger decrease of ~40% was seen in both P15 and P30 ipRGCs after a 1-min recovery, which took up to 10-min to recover to pre-exposure levels. Similarly, the two older age groups had faster and more complete declines in firing over the course of a 1-hr continuous light exposure than the P8 group and then recovered to lower levels (P8 ipRGCs recovered to ~80% of pre-exposure activity, while P15 and P30 ipRGCs recovered to only ~40%.)
We show a generalized decrease in light responses and recovery from light exposure in ipRGCs over the first month of development. These changes occur primarily between days P8 and P15.
This PDF is available to Subscribers Only