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A model for the easy assessment of pressure-dependent damage to retinal ganglion cells using cyan fluorescent protein-expressing transgenic mice.

Tsuruga H, Murata H, Araie M, Aihara M - Mol. Vis. (2012)

Bottom Line: Laser-treated eyes showed a significantly higher IOP than control eyes from 1 to 7 weeks (p<0.01).The pressure insult and the RGC density showed a significant negative correlation (y=-0.070x+97.2, r=0.75, p=0.0008).Moreover, the central, middle, and peripheral areas measured from the optic disc and each of four retinal quadrant areas also showed significant negative correlations.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan.

ABSTRACT

Purpose: To establish an animal model for the easy assessment of pressure-dependent damage to retinal ganglion cells (RGCs) using the B6.Cg-TgN(Thy1-CFP)23Jrs/J transgenic mouse strain (CFP mouse), which expresses cyan fluorescent protein (CFP) in RGCs, and to evaluate pressure-dependent RGC death.

Methods: In 20 CFP mice, right eyes were selected to receive laser-induced ocular hypertension eye and the contralateral eyes remained untouched to serve as controls. Intraocular pressure (IOP) was measured each week in both eyes using the microneedle method up to 8 weeks. Based on the line plot of time (x) and IOP (y) in laser-treated and control eyes, the area surrounded by both lines (∫ΔIOP(y) dx) was calculated as a surrogate value of the pressure insult. At 9 weeks, eyes were enucleated and RGCs expressing CFP were evaluated histologically in retinal whole mounts. The correlation between pressure insult and RGC density was evaluated in the whole eye, three concentric regions, and four quadrants.

Results: Laser-treated eyes showed a significantly higher IOP than control eyes from 1 to 7 weeks (p<0.01). The pressure insult and the RGC density showed a significant negative correlation (y=-0.070x+97.2, r=0.75, p=0.0008). Moreover, the central, middle, and peripheral areas measured from the optic disc and each of four retinal quadrant areas also showed significant negative correlations. Our data demonstrate that each retinal area was almost evenly damaged by IOP elevation.

Conclusions: Laser photocoagulation causes a chronic elevation of IOP in CFP mice. The use of CFP mice enabled us to easily evaluate pressure-dependent RGC damage. This glaucomatous CFP mouse model may contribute to the molecular analysis of neurodegeneration and the development of neuroprotective drugs for glaucoma with a great increase in experimental efficiency.

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Related in: MedlinePlus

Histological evaluation of the optic disc with various pressure-insult. Pressure-insult dependent optic disc damages were histologically evaluated with the laser-treated eyes. The surrogate values of the pressure-insult are B: 53, D: 126, F: 294 and H: 557. Light microscopic images indicate the laser-treated B: D:F:H: and the contralateral control (A, C: E:G: respectively) eyes. Scale bar indicate 50 μm. These figures indicate that the optic disc cupping become larger as the surrogate value is higher.
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f8: Histological evaluation of the optic disc with various pressure-insult. Pressure-insult dependent optic disc damages were histologically evaluated with the laser-treated eyes. The surrogate values of the pressure-insult are B: 53, D: 126, F: 294 and H: 557. Light microscopic images indicate the laser-treated B: D:F:H: and the contralateral control (A, C: E:G: respectively) eyes. Scale bar indicate 50 μm. These figures indicate that the optic disc cupping become larger as the surrogate value is higher.

Mentions: Examples of low- and high- magnification images of the experimental retina are shown in Figure 7. Histological analysis revealed that optic nerve degeneration depended on the pressure insult (Figure 8). Four mice were selected, in which two treated eyes of two mice indicated higher surrogate values, with 294 and 557, and the other two treated eyes indicated lower ones, with 53 and 126; thus, these eyes are representative of higher and lower pressure insults. Excavation of the optic disc was observed at the surrogate values 294 and 557 in laser-treated eyes, but not at the surrogate values 53 and 126. There were no obvious changes in the optic disc of contralateral control eyes.


A model for the easy assessment of pressure-dependent damage to retinal ganglion cells using cyan fluorescent protein-expressing transgenic mice.

Tsuruga H, Murata H, Araie M, Aihara M - Mol. Vis. (2012)

Histological evaluation of the optic disc with various pressure-insult. Pressure-insult dependent optic disc damages were histologically evaluated with the laser-treated eyes. The surrogate values of the pressure-insult are B: 53, D: 126, F: 294 and H: 557. Light microscopic images indicate the laser-treated B: D:F:H: and the contralateral control (A, C: E:G: respectively) eyes. Scale bar indicate 50 μm. These figures indicate that the optic disc cupping become larger as the surrogate value is higher.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472928&req=5

f8: Histological evaluation of the optic disc with various pressure-insult. Pressure-insult dependent optic disc damages were histologically evaluated with the laser-treated eyes. The surrogate values of the pressure-insult are B: 53, D: 126, F: 294 and H: 557. Light microscopic images indicate the laser-treated B: D:F:H: and the contralateral control (A, C: E:G: respectively) eyes. Scale bar indicate 50 μm. These figures indicate that the optic disc cupping become larger as the surrogate value is higher.
Mentions: Examples of low- and high- magnification images of the experimental retina are shown in Figure 7. Histological analysis revealed that optic nerve degeneration depended on the pressure insult (Figure 8). Four mice were selected, in which two treated eyes of two mice indicated higher surrogate values, with 294 and 557, and the other two treated eyes indicated lower ones, with 53 and 126; thus, these eyes are representative of higher and lower pressure insults. Excavation of the optic disc was observed at the surrogate values 294 and 557 in laser-treated eyes, but not at the surrogate values 53 and 126. There were no obvious changes in the optic disc of contralateral control eyes.

Bottom Line: Laser-treated eyes showed a significantly higher IOP than control eyes from 1 to 7 weeks (p<0.01).The pressure insult and the RGC density showed a significant negative correlation (y=-0.070x+97.2, r=0.75, p=0.0008).Moreover, the central, middle, and peripheral areas measured from the optic disc and each of four retinal quadrant areas also showed significant negative correlations.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan.

ABSTRACT

Purpose: To establish an animal model for the easy assessment of pressure-dependent damage to retinal ganglion cells (RGCs) using the B6.Cg-TgN(Thy1-CFP)23Jrs/J transgenic mouse strain (CFP mouse), which expresses cyan fluorescent protein (CFP) in RGCs, and to evaluate pressure-dependent RGC death.

Methods: In 20 CFP mice, right eyes were selected to receive laser-induced ocular hypertension eye and the contralateral eyes remained untouched to serve as controls. Intraocular pressure (IOP) was measured each week in both eyes using the microneedle method up to 8 weeks. Based on the line plot of time (x) and IOP (y) in laser-treated and control eyes, the area surrounded by both lines (∫ΔIOP(y) dx) was calculated as a surrogate value of the pressure insult. At 9 weeks, eyes were enucleated and RGCs expressing CFP were evaluated histologically in retinal whole mounts. The correlation between pressure insult and RGC density was evaluated in the whole eye, three concentric regions, and four quadrants.

Results: Laser-treated eyes showed a significantly higher IOP than control eyes from 1 to 7 weeks (p<0.01). The pressure insult and the RGC density showed a significant negative correlation (y=-0.070x+97.2, r=0.75, p=0.0008). Moreover, the central, middle, and peripheral areas measured from the optic disc and each of four retinal quadrant areas also showed significant negative correlations. Our data demonstrate that each retinal area was almost evenly damaged by IOP elevation.

Conclusions: Laser photocoagulation causes a chronic elevation of IOP in CFP mice. The use of CFP mice enabled us to easily evaluate pressure-dependent RGC damage. This glaucomatous CFP mouse model may contribute to the molecular analysis of neurodegeneration and the development of neuroprotective drugs for glaucoma with a great increase in experimental efficiency.

Show MeSH
Related in: MedlinePlus