Neuroprotection in Glaucoma

Dephosphorylation of ERK1/2 and DRP1 S585 regulates mitochondrial dynamics in glutamate toxicity of retinal neurons in vitro

There are many theories surrounding the pathogenesis of glaucoma, and glutamate excitatory toxicity has been suggested to play an important role. Some studies have shown that glutamate excitatory toxicity is associated with mitochondrial dynamics; however, the relationship between glutamate excitatory toxicity and mitochondrial dynamics in the pathogenesis of glaucoma remains unclear. In this study, the glutamate transporter inhibitor, threohydroxyaspartate, was used to simulate the glutamate excitatory toxicity cell model of rat retinal neurons in vitro, and the changes in the level of proteins related to mitochondrial dynamics, mitochondrial morphology, and length of neuronal axons were measured. We found that in the glutamate excitotoxicity model, retinal neurons can promote mitochondrial fusion by reducing the phosphorylation of ERK1/2 and its downstream protein DRP1 S585, and enhance its ability to resist the excitotoxicity of glutamate. At the same time, the DRP1-specific inhibitor, Mdivi-1, could promote the mitochondrial fusion of retinal neurons.

Molecular changes in glaucomatous trabecular meshwork. Correlations with retinal ganglion cell death and novel strategies for neuroprotection

Glaucoma is a chronic neurodegenerative disease characterized by retinal ganglion cell loss. Although significant advances in ophthalmologic knowledge and practice have been made, some glaucoma mechanisms are not yet understood, therefore, up to now there is no effective treatment able to ensure healing. Indeed, either pharmacological or surgical approaches to this disease aim in lowering intraocular pressure, which is considered the only modifiable risk factor. However, it is well known that several factors and metabolites are equally (if not more) involved in glaucoma. Oxidative stress, for instance, plays a pivotal role in both glaucoma onset and progression because it is responsible for the trabecular meshwork cell damage and, consequently, for intraocular pressure increase as well as for glaucomatous damage cascade. This review at first shows accurately the molecular-derived dysfunctions in antioxidant system and in mitochondria homeostasis which due to both oxidative stress and aging, lead to a chronic inflammation state, the trabecular meshwork damage as well as the glaucoma neurodegeneration. Therefore, the main molecular events triggered by oxidative stress up to the proapoptotic signals that promote the ganglion cell death have been highlighted. The second part of this review, instead, describes some of neuroprotective agents such as polyphenols or polyunsaturated fatty acids as possible therapeutic source against the propagation of glaucomatous damage.