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David Linn, Aula Ramo, Lindsey Lusardi, Lindsey Schroedter, Grace Peterson; DMP-543 increases cell survival in the mammalian retina by enhancing ACh release. Invest. Ophthalmol. Vis. Sci. 2018;59(9):6147.
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© ARVO (1962-2015); The Authors (2016-present)
DMP-543, an acetylcholine (ACh) release enhancer, was originally developed to compensate for the loss of cholinergic neurons in Alzheimer’s disease. We hypothesize that DMP-543 increases the release of ACh from cholinergic amacrine cells and provides neuroprotection in a retinal culture system. In the retina, activation of specific nicotinic ACh receptors (alpha7 nicotinic ACh receptors) has been shown to provide neuroprotection in several glaucoma models.
We examined the effect of DMP-543: 1) on intracellular calcium dynamics in a retinal slice preparation loaded with fluo-4 and examined using a Nikon A1 confocal microscope, 2) on the release of radiolabeled ACh from a perfused eye-cup preparation quantified via liquid scintillation counting and 3) in a dissociated retinal cell culture system where cells were stained with a vital dye, counted and compared to control conditions after 3 days in culture. Adult porcine retina was used for all experiments. Two-tailed Student's t-test was used for statistical analysis.
In slice experiments, cells in the inner nuclear layer displayed a significant increase in relative intensity (threshold) at 2 nM DMP-543 with a 22.5 +/- 3.3% (SEM) maximal increase in relative intensity with 500 nM (N=6, p<0.04). Cells in the retinal ganglion cell layer showed a significant increase in relative intensity at 10 nM and a 81.5 +/- 10.8% (SEM) maximal increase in relative intensity with 500 nM (N=6; p<0.01). This was consistent with ACh release experiments where the threshold for ACh release was determined to be 20 nM DMP-543. Maximal release of labeled ACh occurred during perfusion of 500 nM DMP-543 (N=6, p<0.05). Results from cell culture experiments indicated a threshold dose of 50 nM with a maximal increase of 133.3 +/- 20.1% (SEM) over control conditions with 500 nM DMP-543 (N = 6, p<.008) after 3 days in culture.
Our results are consistent with the hypothesis that DMP-543 increases the release of ACh in the mammalian retina. The data support the concept that DMP-543 affects intracellular calcium to increase the release of ACh in a dose-dependent manner. Furthermore, our dissociated cell culture system can serve as a model for studies analyzing the interaction between activation of cholinergic neurons by ACh release enhancers and neuroprotection by ACh.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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