Dorette Z Ellis1, Linya Li2, Yong Park2, Shaoqing He2, Brett Mueller3, Thomas Yorio2. 1. Department of Pharmaceutical Sciences, University of North Texas Systems College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas, United States 2North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States. 2. North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States. 3. Kentucky Lions Eye Center, University of Louisville, Louisville, Kentucky, United States.
Abstract
Purpose: Understanding the role of mitochondria in retinal ganglion cells (RGCs) is relevant to human disease as studies have shown mitochondrial abnormalities in primary open-angle glaucoma patients. This study seeks to determine the effects of the sigma-1 receptor (σ-1r) and its agonists on mitochondrial function in oxygen- and glucose- deprived (OGD) purified neonatal RGCs. Methods: Retinal ganglion cells were isolated from rat pups and subjected to OGD in varying conditions in the presence or absence of σ-1r agonist and antagonist and following addition of an AAV2-σ-1r vector that was used to increase σ-1r expression. Western blots and immunofluorescence microscopy validated findings. Mitochondrial function was determined by measuring mitochondrial membrane potential (Δψm) using the dye, fluorescence tetraethylbenzimidazolylcarbocyanineiodide (JC-1), and determination of cytochrome c oxidase activity using a cytochrome c oxidase assay kit. Caspase 3 and 7 activities were also measured using a luminescent assay kit. Results: Oxygen and glucose deprivation in RGCs resulted in decreased mitochondrial membrane potential and cytochrome c oxidase activity when compared with normoxic RGCs. σ-1r agonists or overexpression of the σ-1r restored the mitochondrial membrane potential comparable to normoxic conditions, while σ-1r antagonists abolished these effects. Oxygen and glucose depreavtation induced decreases in cytochrome c activity were partially restored by overexpression or activation of σ-1r. Caspase activity was increased in response to OGD and was decreased by the addition of σ-1r agonist, pentazocine, and following σ-1r overexpression. Conclusions: These data suggest that activation and/or overexpression of σ-1r restores RGCs mitochondrial function following OGD and that mitochondrial function is vital to the function of RGCs.
Purpose: Understanding the role of mitochondria in retinal ganglion cells (RGCs) is relevant to human disease as studies have shown mitochondrial abnormalities in primary open-angle glaucomapatients. This study seeks to determine the effects of the sigma-1 receptor (σ-1r) and its agonists on mitochondrial function in oxygen- and glucose- deprived (OGD) purified neonatal RGCs. Methods: Retinal ganglion cells were isolated from rat pups and subjected to OGD in varying conditions in the presence or absence of σ-1r agonist and antagonist and following addition of an AAV2-σ-1r vector that was used to increase σ-1r expression. Western blots and immunofluorescence microscopy validated findings. Mitochondrial function was determined by measuring mitochondrial membrane potential (Δψm) using the dye, fluorescence tetraethylbenzimidazolylcarbocyanineiodide (JC-1), and determination of cytochrome c oxidase activity using a cytochrome c oxidase assay kit. Caspase 3 and 7 activities were also measured using a luminescent assay kit. Results:Oxygen and glucose deprivation in RGCs resulted in decreased mitochondrial membrane potential and cytochrome c oxidase activity when compared with normoxic RGCs. σ-1r agonists or overexpression of the σ-1r restored the mitochondrial membrane potential comparable to normoxic conditions, while σ-1r antagonists abolished these effects. Oxygen and glucose depreavtation induced decreases in cytochrome c activity were partially restored by overexpression or activation of σ-1r. Caspase activity was increased in response to OGD and was decreased by the addition of σ-1r agonist, pentazocine, and following σ-1r overexpression. Conclusions: These data suggest that activation and/or overexpression of σ-1r restores RGCs mitochondrial function following OGD and that mitochondrial function is vital to the function of RGCs.
Authors: Michal Geva; Noga Gershoni-Emek; Luana Naia; Philip Ly; Sandra Mota; Ana Cristina Rego; Michael R Hayden; Leonard A Levin Journal: Sci Rep Date: 2021-11-09 Impact factor: 4.379