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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

IOP elevation in the acute stage after laser photocoagulation. A: IOPs at 1, 2, 3, and 4 h after laser photocoagulation were measured using a TonoLab. B: IOPs at 12, 24, 48, and 72 h after laser photocoagulation were measured by the microneedle method. Data are mean±standard deviation (SD). n=5–6. The IOP of the treated eyes was significantly higher in each time point compared with the IOP of the sham-operated contralateral eyes by a paired t test. (*p<0.05, ** p<0.01).
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f6: IOP elevation in the acute stage after laser photocoagulation. A: IOPs at 1, 2, 3, and 4 h after laser photocoagulation were measured using a TonoLab. B: IOPs at 12, 24, 48, and 72 h after laser photocoagulation were measured by the microneedle method. Data are mean±standard deviation (SD). n=5–6. The IOP of the treated eyes was significantly higher in each time point compared with the IOP of the sham-operated contralateral eyes by a paired t test. (*p<0.05, ** p<0.01).

Mentions: To evaluate whether acute IOP elevation occurred after laser photocoagulation, we measured early IOP changes during the first 1–72 h. For the first 4 h, both the laser-induced ocular hypertension eyes and the sham-operated contralateral eyes gradually increased in IOP. However, the laser-induced ocular hypertension eyes showed a significant IOP elevation from 24 h to 72 h after laser photocoagulation compared with the IOP of sham-operated eyes without flattening of the anterior chamber (p<0.05; Figure 6). There was no significant difference from 1 h to 12 h. The IOP of sham-operated C57BL6/J eyes was 15.2 mmHg after 4 h, which is similar to that of nontreated eyes in a previous report [24,25]; this IOP was stable for 72 h. Consequently, the investigation revealed that the IOP of laser-treated eyes gradually increased until 24 h and sustained ocular hypertension.


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)

IOP elevation in the acute stage after laser photocoagulation. A: IOPs at 1, 2, 3, and 4 h after laser photocoagulation were measured using a TonoLab. B: IOPs at 12, 24, 48, and 72 h after laser photocoagulation were measured by the microneedle method. Data are mean±standard deviation (SD). n=5–6. The IOP of the treated eyes was significantly higher in each time point compared with the IOP of the sham-operated contralateral eyes by a paired t test. (*p<0.05, ** p<0.01).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: IOP elevation in the acute stage after laser photocoagulation. A: IOPs at 1, 2, 3, and 4 h after laser photocoagulation were measured using a TonoLab. B: IOPs at 12, 24, 48, and 72 h after laser photocoagulation were measured by the microneedle method. Data are mean±standard deviation (SD). n=5–6. The IOP of the treated eyes was significantly higher in each time point compared with the IOP of the sham-operated contralateral eyes by a paired t test. (*p<0.05, ** p<0.01).
Mentions: To evaluate whether acute IOP elevation occurred after laser photocoagulation, we measured early IOP changes during the first 1–72 h. For the first 4 h, both the laser-induced ocular hypertension eyes and the sham-operated contralateral eyes gradually increased in IOP. However, the laser-induced ocular hypertension eyes showed a significant IOP elevation from 24 h to 72 h after laser photocoagulation compared with the IOP of sham-operated eyes without flattening of the anterior chamber (p<0.05; Figure 6). There was no significant difference from 1 h to 12 h. The IOP of sham-operated C57BL6/J eyes was 15.2 mmHg after 4 h, which is similar to that of nontreated eyes in a previous report [24,25]; this IOP was stable for 72 h. Consequently, the investigation revealed that the IOP of laser-treated eyes gradually increased until 24 h and sustained ocular hypertension.

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