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Protective role of melatonin on retinal ganglionar cell: In vitro an in vivo evidences
摘要： Oxidative stress triggers ocular neurodegenerative diseases, such as glaucoma or macular degeneration. The increase of reactive oxygen and nitrogen species in retinal ganglion cells (RGCs) causes damage to the structure and function of the axons that make up the optic nerve, leading to cell death arising from apoptosis, necrosis or autophagy in the RCGs. The use of antioxidants to prevent visual neurodegenerative pathologies is a novel and possibly valuable therapeutic strategy. To investigate in vitro and in vivo neuroprotective efficacy of melatonin (MEL) in RGCs, we used a model of oxidative glutamate (GLUT) toxicity in combination with L-butionin-S, R-sulfoximine (BSO), which induces cell death by apoptosis through cytotoxicity and oxidative stress mechanisms. Histological sectioning and immunohistochemical assays using the TUNEL technique were performed to determine the damage generated in affected cells and to observe the death process of RGCs. Whit BSO-GLUT the results revealed a progressive RGCs death without any significant evidence of a decreased retinal function after 9 days of treatment. In this way, we were able to develop a retinal degeneration model in vivo to carry out treatment with MEL and observed an increase in the survival percentage of RGCs, showing that BSO-GLUT could not exert an oxidant effect on cells to counteract the effect of MEL. These findings reveal that MEL has a neuroprotective and antiapoptotic effect as evidenced by the reduction of oxidative stress damage. MEL demonstrated in this model makes it a promising neuroprotective agent for the treatment of ocular neurodegenerative diseases when administered locally.
关键词： Ganglion retinal cells (RGCs),Oxidative stress,Neuroprotection,Melatonin
更新于2025-09-23 15:23:52
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Yellow filter effect on melatonin secretion in the eye: Role in IOP regulation
摘要： Purpose: Melatonin is a neurohormone mainly synthesized in the pineal gland; however, it is also present in the aqueous humor. One of melatonins’ functions in the eye is the regulation of intraocular pressure. Melatonin is known to be sensitive to light. Recently, the photopigment which controls melatonin synthesis, melanopsin, was found in the crystalline lens. Therefore, light conditions is an interesting possible way of regulating melatonin levels in the aqueous humor. The current study used yellow-filters, since melanopsin is activated by short-wavelength (blue light). methods: New Zealand white rabbits were used, divided in two groups, one under controlled 12h-light/dark cycles, while the rest had their cages encased with a yellow filter (λ 465-480). IOP measurements were taken every week at the same time before they were anesthetized for aqueous humour extraction. Results: Keeping the rabbits under the yellow filter resulted in a decrease in IOP up to 43.8 ± 7.8% after 3 weeks. This effect was reversed after the topical application of selective and non-selective melatonin receptors antgonists, 4PPDOT and luzindole. Also, blocking melanopsin by its antagonist AA92593 under white light condition decreased IOP. Finally, melatonin levels were found significantly higher in the aqueous humor of rabbits developed under yellow filter compared to controls (37.4 ± 4.2 ng/ml and 15.3 ± 3.1 ng/ml, respectively). Conclusion: Yellow filters modulate melatonin levels in the aqueous humour due to deactivating melanopsin activity. This effect leaded to a decrease in IOP mediated by melatonin receptors.
关键词： Melatonin,Intraocular pressure,Melanopsin.,Yellow filter
更新于2025-09-23 15:22:29
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Melatonin suppression is exquisitely sensitive to light and primarily driven by melanopsin in humans
摘要： Introduction: Light elicits a range of non-visual responses in humans. Driven predominantly by intrinsically photosensitive retinal ganglion cells (ipRGCs), but also by rods and/or cones, these responses include melatonin suppression. A sigmoidal relationship has been established between melatonin suppression and light intensity, however photoreceptoral involvement remains unclear. Methods and Results: In this study, we first modelled the relationships between alpha-opic illuminances and melatonin suppression using an extensive dataset by Brainard and colleagues. Our results show that 1) melatonin suppression is better predicted by melanopic illuminance compared to other alpha-opic illuminances, 2) melatonin suppression is predicted to occur at levels as low as ~1.5 melanopic lux (melanopsin-weighted irradiance 0.2 μW/cm2), 3) saturation occurs at 305 melanopic lux (melanopsin-weighted irradiance 36.6 μW/cm2). We then tested this melanopsin-weighted illuminance response model derived from Brainard and colleagues’ data and show that it predicts equally well melatonin suppression data from our laboratory, although obtained using different intensities and exposure duration. Discussion: Together, our findings suggest that melatonin suppression by monochromatic lights is predominantly driven by melanopsin, and that it can be initiated at extremely low melanopic lux levels in experimental conditions. This emphasizes the concern of the non-visual impacts of low light intensities in lighting design and light-emitting devices.
关键词： melatonin,light,mathematical model,dose-response relationship,humans,circadian,melanopsin
更新于2025-09-19 17:15:36
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OLEDs with Candle-Like Emission
摘要： Candle-like organic light-emitting diodes (OLEDs) emit much less blue light than other non-incandescent light sources. This type of OLED is characterized by low correlated color temperature (CCT), chromaticity tunability, and low melatonin (MLT) suppression. The light evokes a sense of warmth and creates a pleasant and calming ambience with its high-quality diffuse orange-red emission.
关键词： OLEDs,Color Temperature,Candle-Like Emission,Blue Light,Melatonin Suppression
更新于2025-09-12 10:27:22