Crocin protects retinal ganglion cells against H2O2-induced damage through the mitochondrial pathway and activation of NF-κB

Abstract

Glaucoma is a degenerative nerve disorder that results in irreversible blindness. It has been reported that the apoptosis of retinal ganglion cells (RGCs) is a hallmark of glaucoma. Oxidative stress is one of the major factors that cause apoptosis of RGCs. Crocin has many beneficial effects, including antioxidant and anti-apoptotic actions. However, the mechanism by which crocin protects against oxidative stress‑induced damage to RGCs remains unclear. The present study aimed to investigate the mechanism by which crocin protects RGC-5 cells against H2O2-induced damage. H2O2 was used to establish a model of oxidative stress injury in RGC-5 cells to mimic the development of glaucoma in vitro. Different concentrations (0.1 and 1 µM) of crocin were added to test whether crocin was capable of protecting RGCs from H2O2-induced damage. WST-1, lactic dehydrogenase (LDH) release and Annexin V/FITC assays were then performed. Levels of reactive oxygen species (ROS) were detected using a ROS assay kit, mitochondrial membrane potential (ΔΨm) was analyzed by JC-1 staining, caspase-3 activity was examined using a Caspase-3 assay kit, and the protein levels of Bax, Bcl-1 and cytochrome c were measured using western blot analysis. In addition, the protein level of phosphorylated nuclear factor-κB (p-NF-κB) p65 was also evaluated using western blot analysis. The results showed that crocin protected RGC-5 cells from apoptosis, decreased LDH release and enhanced cell viability. Additional experiments demonstrated that crocin decreased ROS levels, increased ΔΨm, downregulated the protein expression of Bax and cytochrome c, promoted Bcl-2 protein expression and activated NF-κB. Taken together, the findings of this study indicate that crocin prevented H2O2‑induced damage to RGCs through the mitochondrial pathway and activation of NF-κB.

Crocin, a plant-derived carotenoid, modulates microglial reactivity

“…Saffron and its active ingredients mainly crocin, crocetin and safranal exert anti-proliferative, anti-tumor, anti-inflammatory, anti-oxidant, anti-apoptotic, and hepatoprotective effects [12] . Administration of saffron components in different models of retinal damage and degeneration showed neuroprotective effects [13] , [14] . Likewise, safranal could slow down photoreceptor degeneration in the P23H rat model of retinitis pigmentosa, reflected by improved a- and b-wave amplitudes in electroretinographic recordings and a preserved vascular network [14] .…”

Protective effect of crocin on ultraviolet B‑induced dermal fibroblast photoaging

“…It has been shown previously that crocin exhibits multiple activities, including anti-cancer, anti-inflammatory and anti-oxidation effects in various cell types ( 7 ). Lv et al ( 8 ) reported that crocin exerts an anti-oxidative effect against H 2 O 2 -induced apoptosis in retinal ganglion cells.…”

Reactive Oxygen Species-Mediated Damage of Retinal Neurons: Drug Development Targets for Therapies of Chronic Neurodegeneration of the Retina

“…Mitochondrial stress leads to the release of cell death mediators, which compromise oxidative phosphorylation, leading to inefficient use of protons and the relative over- and underproduction of ROS and adenosine triphosphate (ATP) respectively [ 28 , 40 ]. The associated increase in ROS may be involved in the propagation of RGC apoptosis via mediation of mitochondrial permeability transition, alteration of mitochondrial membrane potential, and release of pro-apoptotic proteins [ 28 , 41 ]. SkQ1, mentioned previously, has been shown to prevent mitochondrial damage in fibroblasts in the presence of oxidative stress and stimulate formation of the mitochondrial network in the absence of oxidative stress by reducing endogenous ROS levels [ 42 ].…”

“…The administration of tempol, which has been shown to prevent ROS generation and neuronal cell death, increases survival of RGCs exposed to tumor necrosis factor-alpha (TNF-α) and hypoxia in the presence of a caspase inhibitor [ 28 ]. Furthermore, crocin, a carotenoid, has been shown to suppress production of ROS, increase mitochondrial membrane potential, and enhance viability in hydrogen peroxide (H 2 O 2 )-insulted RGCs [ 41 ]. Molecular hydrogen has also been demonstrated to suppress loss of mitochondrial membrane potential and apoptosis in retinal cells, presumably via peroxynitrite scavenging [ 34 ].…”