Comparison of basal oscillatory rhythm of retinal activities in rd1 and rd10 mice.
ABSTRACT Among the many animal models of retinitis pigmentosa (RP), the most extensively characterized animal is the rd1 mouse. Recent studies showed that the neurophysiological properties of rd1 retinas differ significantly from those of normal retina; the presence of an oscillatory rhythmic activity (~10 Hz) both in retinal ganglion cell (RGC) spikes and field potentials (slow wave component, SWC). However, lesser studies have been done regarding electrical characteristics of rd10 retina, carrying the mutation of same rod-PDE gene and showing a later onset degeneration of photoreceptors. Therefore, in this study, we compared the oscillatory rhythm in RGC spike and SWC between rd1 and rd10 mice in different postnatal ages to understand neural code used by two diseased retinas to communicate with the brain. Extracellular action potentials are recorded by 8 × 8 MEA from the RGC in the in vitro whole mount retina. 4 and 8 weeks in rd1 mice and 4, 10, 15, and 20 weeks in rd10 mice were used (n=3 for each postnatal age). From the raw waveform of retinal recording, RGC Spikes and SWC were isolated by using 200 Hz high-pass filter and 20 Hz low-pass filter, respectively. Fourier transform was performed for detection of oscillatory rhythm in RGC spikes and SWC. In rd1 mice, there is no statistical difference between the frequency of SWC and spike in 4 weeks [p>0.05; spike 9.3 ± 0.9 Hz (n=40), SWC 9.3 ± 1.5 Hz (n=25)] and 8 weeks [p>0.05; spike 10.0 ± 1.3 Hz (n=87), SWC 10.9 ± 1.7 Hz (n=25)]. While in rd10 mice there is no statistical differences among the SWC through 4 ~ 20 weeks, significant differences were observed between the frequency of RGC spike and SWC and also among RGC spikes [4 weeks (p<0.001): spike 5.5 ± 1.3 Hz (n=59), SWC 10.8 ± 3.1 Hz (n=14); 10 weeks (p<0.001): spike 6.8 ± 3.8 Hz (n=79), SWC 10.3 ± 2.6 Hz (n=25); 15 weeks (p<0.05): spike 3.9 ± 0.7 Hz (n=33), SWC 9.9 ± 1.2 Hz (n=25); 20 weeks (p<0.05): spike 4.4 ± 1.2 Hz (n=53), SWC 9.8 ± 1.2 Hz (n=25)].
Article: Spontaneous Oscillatory Rhythm in Retinal Activities of Two Retinal Degeneration (rd1 and rd10) Mice.[show abstract] [hide abstract]
ABSTRACT: Previously, we reported that besides retinal ganglion cell (RGC) spike, there is ~ 10 Hz oscillatory rhythmic activity in local field potential (LFP) in retinal degeneration model, rd1 mice. The more recently identified rd10 mice have a later onset and slower rate of photoreceptor degeneration than the rd1 mice, providing more therapeutic potential. In this study, before adapting rd10 mice as a new animal model for our electrical stimulation study, we investigated electrical characteristics of rd10 mice. From the raw waveform of recording using 8×8 microelectrode array (MEA) from in vitro-whole mount retina, RGC spikes and LFP were isolated by using different filter setting. Fourier transform was performed for detection of frequency of bursting RGC spikes and oscillatory field potential (OFP). In rd1 mice, ~10 Hz rhythmic burst of spontaneous RGC spikes is always phase-locked with the OFP and this phase-locking property is preserved regardless of postnatal ages. However, in rd10 mice, there is a strong phase-locking tendency between the spectral peak of bursting RGC spikes (~5 Hz) and the first peak of OFP (~5 Hz) across different age groups. But this phase-locking property is not robust as in rd1 retina, but maintains for a few seconds. Since rd1 and rd10 retina show phase-locking property at different frequency (~10 Hz vs. ~5 Hz), we expect different response patterns to electrical stimulus between rd1 and rd10 retina. Therefore, to extract optimal stimulation parameters in rd10 retina, first we might define selection criteria for responding rd10 ganglion cells to electrical stimulus.Korean Journal of Physiology and Pharmacology 12/2011; 15(6):415-22. · 0.96 Impact Factor