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Cannabinoid receptor 1 blockade protects human retinal pigment epithelial cells from oxidative injury
1Department of Ophthalmology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
Background:
Because oxidative stress is assumed to be a key mechanism in the pathological process of age-related macular degeneration (AMD), increasing numbers of studies have focused on discovering new pathways and treatments for reducing oxidative damage. Our work investigates the potential role of the cannabinoid receptor 1 (CB1) in oxidative stress of primary human retinal pigment epithelial (RPE) cells, a cellular model of AMD.
Methods:
Primary human RPE cells were cultured and exposed to hydrogen peroxide for 24 h to induce oxidative damage. The expression of and changes in the CB1 receptor were determined with western blot assay and confocal imaging. The CB1 receptor in the RPE cells was inhibited with small interfering RNA (siRNA) or rimonabant (SR141716). Cell viability, apoptosis, and reactive oxygen species production were measured by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and sulforhodamine B assay, annexin V and propidium iodide staining, and the dichlorofluorescein fluorescence assay, respectively. Intracellular superoxide dismutase activity was assayed with a commercially available assay kit. Phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) protein expression and activation of signaling molecules were assessed with western blot analysis.
Results:
We showed that human RPE cells express the CB1 receptor. In addition, oxidative stress upregulates the expression of the CB1 receptor. Deleting the CB1 receptor or treating with the CB1 receptor antagonist rimonabant (SR141716) rescued RPE cells from hydrogen peroxide-induced oxidative damage. Rimonabant pretreatment effectively reduced the apoptosis of RPE cells, inhibited the generation of intracellular reactive oxygen species and elevated the activity of superoxide dismutase. In addition, rimonabant significantly strengthened the oxidative stress-induced activation of the PI3K/Akt signaling pathway.
Conclusions:
The results demonstrate the expression and regulation of CB1 receptors in human RPE cells. Inhibiting the CB1 receptor may be an effective therapeutic strategy for AMD by downregulating oxidative stress signaling and facilitating PI3K/Akt activation.
Insights
Inhibiting the cannabinoid receptor 1 (CB1) in retinal pigment epithelial cells protects against oxidative stress, a key factor in age-related macular degeneration (AMD). This suggests CB1 inhibition as a potential therapeutic strategy for AMD.
Area of Science:
- Ophthalmology
- Cell Biology
- Pharmacology
Background:
- Oxidative stress is implicated in age-related macular degeneration (AMD) pathogenesis.
- Research is ongoing to identify pathways and treatments for reducing oxidative damage in AMD.
- This study investigates the role of cannabinoid receptor 1 (CB1) in oxidative stress within human retinal pigment epithelial (RPE) cells, a model for AMD.
Purpose of the Study:
- To investigate the expression and function of CB1 receptors in human RPE cells under oxidative stress.
- To determine if modulating CB1 receptor activity impacts oxidative damage in RPE cells.
- To explore the therapeutic potential of CB1 receptor inhibition for AMD.
Main Methods:
- Human RPE cells were cultured and subjected to hydrogen peroxide-induced oxidative stress.
- CB1 receptor expression was analyzed using western blot and confocal imaging.
- CB1 receptor was inhibited using siRNA or the antagonist rimonabant (SR141716).
- Cell viability, apoptosis, reactive oxygen species (ROS) production, and superoxide dismutase (SOD) activity were measured.
- PI3K/Akt signaling pathway activation was assessed via western blot.
Main Results:
- Human RPE cells express CB1 receptors, with expression upregulated by oxidative stress.
- Inhibition of CB1 receptors (via siRNA or rimonabant) protected RPE cells from hydrogen peroxide-induced damage.
- Rimonabant reduced RPE cell apoptosis, inhibited ROS generation, and increased SOD activity.
- CB1 receptor inhibition enhanced the activation of the PI3K/Akt signaling pathway.
Conclusions:
- CB1 receptors are expressed and regulated in human RPE cells.
- Inhibiting CB1 receptors demonstrates a protective effect against oxidative stress in RPE cells.
- Targeting CB1 receptors may represent a viable therapeutic approach for AMD by modulating oxidative stress and activating the PI3K/Akt pathway.
