Abstract
Purpose :
To demonstrate that application of the alpha7 nicotinic acetylcholine receptor selective agonist, PNU-282987, elicits new neurons in a blast damaged retina and recovery of retinal function.
Methods :
Ocular blast damage was induced in adult mice (3-8 months old; both sexes) after exposure to a single blast of 35 psi to the left eye. Blast exposed transgenic mice expressing TdTomato Müller glia, were treated daily with an eyedrop solution containing 1mM PNU-282987 post-blast for 4 weeks. Antibody staining studies were performed to study regeneration of new neurons derived from Müller glia and ERGs were obtained each week to examine functional recovery. ERG recordings were obtained from control, blast damaged and mice exposed to blast followed by 4 weeks of PNU-282987 treatment. Recordings were obtained using the Celeris Diagnosis system. Data was analyzed with ANOVA and significant differences were indicated as P<0.05. N’s between 4-6 were obtained under each condition.
Results :
Blast exposure caused a significant loss of cells in all retinal layers after 4 weeks, ranging between 15 and 40% (+/- 8.2) compared to unblasted eyes. Immunohistochemical analysis demonstrated double labeled TdTom positive photoreceptors, bipolar cells, amacrine cells and retinal ganglion cells in blast exposed mice treated with PNU-282987. Scotopic ERG recordings from blast exposed mice had significantly decreased amplitudes in a-waves, b-waves, and oscillatory potentials (OP1,2,3) (between 35 and 47% +/- 6) compared to ERGs obtained from the same mice prior to blast exposure. Significantly decreased amplitudes were also seen from scotopic flicker frequency recordings at 5, 10, 20 and 30 Hz (between 31 and 52% +/-11) following blast exposure. Animals treated with PNU-282987 for 4 weeks after blast showed a significant recovery in a-wave amplitudes by 45% +/-12, in b-waves by 35% +/-11, and in OP1,2 and 3 waves (between 43 to 82% +/-25). Recovery of flicker amplitudes of 5, 10, 20 and 30 Hz were measured between 20 and 48% +/-10 when compared to responses from the same mice under control conditions.
Conclusions :
Blast exposure caused a significant loss of cells in all retinal layers and a reduction in ERG waveform amplitudes. After treatment with PNU-282987 for 1 month, newly generated neurons derived from Müller glia were found in all retinal layers, which corresponded with recovery of ERG responses.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.