Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma
Glaucoma is the second leading cause of blindness worldwide and is, in most cases, a consequence of elevated intraocular pressure (IOP), ultimately resulting in the death of retinal ganglion cells (RGCs). Current treatments are mostly focused on normalizing IOP, but we propose the additional use of...
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| author | Ronan Nakamura Nicolás S. Ciranna Juan C. Fernández Rafael Peláez Álvaro Pérez-Sala Miriam Bobadilla Juan J. López-Costa César F. Loidl Alfredo Martínez Manuel Rey-Funes |
| author_facet | Ronan Nakamura Nicolás S. Ciranna Juan C. Fernández Rafael Peláez Álvaro Pérez-Sala Miriam Bobadilla Juan J. López-Costa César F. Loidl Alfredo Martínez Manuel Rey-Funes |
| author_sort | Ronan Nakamura |
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| description | Glaucoma is the second leading cause of blindness worldwide and is, in most cases, a consequence of elevated intraocular pressure (IOP), ultimately resulting in the death of retinal ganglion cells (RGCs). Current treatments are mostly focused on normalizing IOP, but we propose the additional use of neuroprotective agents, including methylene blue (MB), to block the loss of RGCs. Wistar rats were subjected to episcleral vein cauterization (EVC) in the left eye while the right eye was sham-operated. One week later, they were divided into two groups, which were injected with either 2.0 mg/kg MB or phosphate-buffered saline (PBS), twice a day, for 7 days. Fifteen days after surgery, rats were tested with scotopic electroretinography (ERG) or pattern electroretinography (PERG). After sacrifice, the number of RGCs and the thickness of the inner retina (IR) were evaluated both in the peripheral and central areas of the retina. Scotopic ERG showed a marked reduction (<i>p</i> < 0.0001) on the a- and b-wave amplitude and oscillatory potential (OP) complexity of the eyes subjected to EVC. These parameters were significantly (<i>p</i> < 0.01) restored by the application of MB. PERG indicated that EVC was responsible for a very significant decrease in N2 amplitude (<i>p</i> < 0.0001) and prolongation of N2 implicit time (<i>p</i> < 0.0001). Treatment with MB significantly restored N2 amplitude (<i>p</i> < 0.0001). In parallel with the ERG results, morphological analysis showed a significant loss of RGCs (<i>p</i> < 0.0001) and IR thickness (<i>p</i> < 0.0001) in both the peripheral and central retinas subjected to EVC, which was significantly prevented (<i>p</i> < 0.0001) by MB treatment. We have shown that MB treatment can be effective in preventing physiological and morphological hallmarks of optic neuropathy in a model of ocular hypertension, which faithfully recapitulates human open-angle glaucoma. Due to its high safety profile, this drug could therefore represent a new pharmacologic strategy to prevent vision loss in glaucoma patients. |
| format | Article |
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| spelling | doaj-art-5effb27710bd42a4a67e34a421fd99512025-08-20T01:56:05ZengMDPI AGBiomedicines2227-90592024-09-01129198310.3390/biomedicines12091983Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of GlaucomaRonan Nakamura0Nicolás S. Ciranna1Juan C. Fernández2Rafael Peláez3Álvaro Pérez-Sala4Miriam Bobadilla5Juan J. López-Costa6César F. Loidl7Alfredo Martínez8Manuel Rey-Funes9Institute of Cell Biology and Neurosciences “Prof. E. De Robertis”, Faculty of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, ArgentinaInstitute of Cell Biology and Neurosciences “Prof. E. De Robertis”, Faculty of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, ArgentinaInstitute of Cell Biology and Neurosciences “Prof. E. De Robertis”, Faculty of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, ArgentinaBiomarkers and Molecular Signaling Group, Neurodegenerative Diseases Area, Center for Biomedical Research of La Rioja (CIBIR), 26006 Logroño, SpainBiomarkers and Molecular Signaling Group, Neurodegenerative Diseases Area, Center for Biomedical Research of La Rioja (CIBIR), 26006 Logroño, SpainBiomarkers and Molecular Signaling Group, Neurodegenerative Diseases Area, Center for Biomedical Research of La Rioja (CIBIR), 26006 Logroño, SpainInstitute of Cell Biology and Neurosciences “Prof. E. De Robertis”, Faculty of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, ArgentinaInstitute of Cell Biology and Neurosciences “Prof. E. De Robertis”, Faculty of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, ArgentinaAngiogenesis Group, Oncology Area, Center for Biomedical Research of La Rioja (CIBIR), 26006 Logroño, SpainInstitute of Cell Biology and Neurosciences “Prof. E. De Robertis”, Faculty of Medicine, University of Buenos Aires, Buenos Aires C1121ABG, ArgentinaGlaucoma is the second leading cause of blindness worldwide and is, in most cases, a consequence of elevated intraocular pressure (IOP), ultimately resulting in the death of retinal ganglion cells (RGCs). Current treatments are mostly focused on normalizing IOP, but we propose the additional use of neuroprotective agents, including methylene blue (MB), to block the loss of RGCs. Wistar rats were subjected to episcleral vein cauterization (EVC) in the left eye while the right eye was sham-operated. One week later, they were divided into two groups, which were injected with either 2.0 mg/kg MB or phosphate-buffered saline (PBS), twice a day, for 7 days. Fifteen days after surgery, rats were tested with scotopic electroretinography (ERG) or pattern electroretinography (PERG). After sacrifice, the number of RGCs and the thickness of the inner retina (IR) were evaluated both in the peripheral and central areas of the retina. Scotopic ERG showed a marked reduction (<i>p</i> < 0.0001) on the a- and b-wave amplitude and oscillatory potential (OP) complexity of the eyes subjected to EVC. These parameters were significantly (<i>p</i> < 0.01) restored by the application of MB. PERG indicated that EVC was responsible for a very significant decrease in N2 amplitude (<i>p</i> < 0.0001) and prolongation of N2 implicit time (<i>p</i> < 0.0001). Treatment with MB significantly restored N2 amplitude (<i>p</i> < 0.0001). In parallel with the ERG results, morphological analysis showed a significant loss of RGCs (<i>p</i> < 0.0001) and IR thickness (<i>p</i> < 0.0001) in both the peripheral and central retinas subjected to EVC, which was significantly prevented (<i>p</i> < 0.0001) by MB treatment. We have shown that MB treatment can be effective in preventing physiological and morphological hallmarks of optic neuropathy in a model of ocular hypertension, which faithfully recapitulates human open-angle glaucoma. Due to its high safety profile, this drug could therefore represent a new pharmacologic strategy to prevent vision loss in glaucoma patients.https://www.mdpi.com/2227-9059/12/9/1983glaucomaepiscleral vein cauterizationmethylene bluerat modelscotopic electroretinographypattern electroretinography |
| spellingShingle | Ronan Nakamura Nicolás S. Ciranna Juan C. Fernández Rafael Peláez Álvaro Pérez-Sala Miriam Bobadilla Juan J. López-Costa César F. Loidl Alfredo Martínez Manuel Rey-Funes Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma Biomedicines glaucoma episcleral vein cauterization methylene blue rat model scotopic electroretinography pattern electroretinography |
| title | Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma |
| title_full | Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma |
| title_fullStr | Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma |
| title_full_unstemmed | Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma |
| title_short | Methylene Blue Reduces Electroretinogram Distortion and Ganglion Cell Death in a Rat Model of Glaucoma |
| title_sort | methylene blue reduces electroretinogram distortion and ganglion cell death in a rat model of glaucoma |
| topic | glaucoma episcleral vein cauterization methylene blue rat model scotopic electroretinography pattern electroretinography |
| url | https://www.mdpi.com/2227-9059/12/9/1983 |
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