Neuroprotective effect of omidenepag on excitotoxic retinal ganglion cell death regulating COX-2–EP2–cAMP–PKA/Epac pathway via Neuron–Glia interaction

• Published in: Neuroscience 2024-08, Vol.553, p.145-159
• Main Authors: Nakamura, Natsuko, Honjo, Megumi, Yamagishi-Kimura, Reiko, Sakata, Rei, Watanabe, Sumiko, Aihara, Makoto
• Format: Article
• Language: English
• Subjects: Animals; Cell Death - drug effects; Cell Death - physiology; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Cyclooxygenase 2 - metabolism; EP2 receptor agonist; Glutamate excitotoxicity; Glutamic Acid - metabolism; Glutamic Acid - toxicity; Guanine Nucleotide Exchange Factors - metabolism; Male; Mice; Mice, Inbred C57BL; N-Methylaspartate - pharmacology; N-Methylaspartate - toxicity; Neuroglia - drug effects; Neuroglia - metabolism; Neurons - drug effects; Neurons - metabolism; Neuron–Glia Interaction; Neuroprotective Agents - pharmacology; Omidenepag; Rats; Rats, Sprague-Dawley; Receptors, Prostaglandin E, EP2 Subtype - agonists; Receptors, Prostaglandin E, EP2 Subtype - antagonists & inhibitors; Receptors, Prostaglandin E, EP2 Subtype - metabolism; Retinal Ganglion Cells - drug effects; Retinal Ganglion Cells - metabolism; RGC death; Signal Transduction - drug effects; Signal Transduction - physiology
• ISSN: 0306-4522; 1873-7544; 1873-7544
• DOI: 10.1016/j.neuroscience.2024.07.006

•OMD inhibits glutamate-induced RGC death directly and indirectly via glia.•OMD suppresses glutamate-induced Epac1 upregulation and activates the PKA pathway.•OMD may have neuroprotective effects by modulating glia–neuron interaction. Glutamate excitotoxicity is involved in retinal ganglion cell (RGC) death in various retinal degenerative diseases, including ischemia–reperfusion injury and glaucoma. Excitotoxic RGC death is caused by both direct damage to RGCs and indirect damage through neuroinflammation of retinal glial cells. Omidenepag (OMD), a novel E prostanoid receptor 2 (EP2) agonist, is a recently approved intraocular pressure-lowering drug. The second messenger of EP2 is cyclic adenosine monophosphate (cAMP), which activates protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). In this study, we investigated the neuroprotective effects of OMD on excitotoxic RGC death by focusing on differences in cAMP downstream signaling from the perspective of glia–neuron interactions. We established a glutamate excitotoxicity model in vitro and NMDA intravitreal injection model in vivo. In vitro, rat primary RGCs were used in an RGC survival rate assay. MG5 cells (mouse microglial cell line) and A1 cells (astrocyte cell line) were used for immunocytochemistry and Western blotting to evaluate the expressions of COX-1/2, PKA, Epac1/2, pCREB, cleaved caspase-3, inflammatory cytokines, and neurotrophic factors. Mouse retinal specimens underwent hematoxylin and eosin staining, flat-mounted retina examination, and immunohistochemistry. OMD significantly suppressed excitotoxic RGC death, cleaved caspase-3 expression, and activated glia both in vitro and in vivo. Moreover, it inhibited Epac1 and inflammatory cytokine expression and promoted COX-2, pCREB, and neurotrophic factor expression. OMD may have neuroprotective effects through inhibition of the Epac pathway and promotion of the COX-2–EP2–cAMP–PKA pathway by modulating glia–neuron interaction.