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High levels of retinal docosahexaenoic acid do not protect photoreceptor degeneration in VPP transgenic mice.

Li F, Marchette LD, Brush RS, Elliott MH, Davis KR, Anderson AG, Anderson RE - Mol. Vis. (2010)

Bottom Line: Offspring were genotyped and four groups identified: Fat1(+)/VPP(+), Fat1(-)/VPP(+), Fat1(+)/VPP(-), and Fat1(-)/VPP(-).Dams were maintained on the SFO diet during the nursing period and offspring were kept on the SFO diet after weaning.There were no significant differences in outer nuclear layer thickness or ERG amplitudes between Fat1(+)/VPP(+) and Fat1(-)/VPP(+), or between Fat1(+)/VPP(-)and Fat1(-)/VPP(-) mice at any of the three ages.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.

ABSTRACT

Purpose: To determine whether docosahexaenoic acid can protect against hereditary retinal degenerations in transgenic mice expressing the V20G, P23H, and P27L (VPP) rhodopsin mutations.

Methods: Female transgenic mice expressing the VPP rhodopsin mutation, known to cause a retinal degeneration, were bred to male transgenic mice expressing the fat-1 gene, which can convert n6 to n3 polyunsaturated fatty acids (PUFA). Several weeks before breeding, the female mice were fed a standard diet containing 10% safflower oil (SFO), which is high in n6 and low in n3 PUFA (n6/n3=273). Offspring were genotyped and four groups identified: Fat1(+)/VPP(+), Fat1(-)/VPP(+), Fat1(+)/VPP(-), and Fat1(-)/VPP(-). Dams were maintained on the SFO diet during the nursing period and offspring were kept on the SFO diet after weaning. At 4, 16, and 28 weeks of age, retinal function was evaluated by electroretinography (ERG), photoreceptor cell loss was quantified by measuring outer nuclear layer thickness, and rhodopsin levels were determined. Fatty acid profiles were analyzed in whole retina, plasma, and liver at 4 and 28 weeks of age.

Results: Expression of fat-1 in the absence of dietary n3 PUFA led to the generation of two groups of mice with distinctly different levels of n3 and n6 PUFA in the three tissues that were analyzed. Already at four weeks of age, the retinas of fat-1 positive animals had higher levels of n3 PUFA than their wild-type counterparts (23%-29% versus 6.4%-6.5%). In addition, by four weeks of age, there was a significant loss of rod photoreceptor cells in the VPP mice. Progression of retinal degeneration occurred with increasing age in VPP positive mice, with photoreceptor cell death occurring in both inferior and superior regions. Amplitudes of the a- and b-waves of the ERG were significantly reduced with age, with VPP positive mice showing the greatest change. Rhodopsin content was lower in the VPP transgenic mice. There were no significant differences in outer nuclear layer thickness or ERG amplitudes between Fat1(+)/VPP(+) and Fat1(-)/VPP(+), or between Fat1(+)/VPP(-)and Fat1(-)/VPP(-) mice at any of the three ages.

Conclusions: High levels of retinal docosahexaenoic acid do not protect mice expressing the VPP rhodopsin mutation from retinal degeneration.

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Related in: MedlinePlus

Quantification of morphological changes. The quantification of morphological changes are shown by measurements of outer nuclear layer (ONL) thickness along the vertical meridian of the eye in Fat1+/VPP+, Fat1–/VPP+, Fat1+/VPP–, and Fat1–/VPP– mice maintained in 20 lx cyclic light (n=10). A, C, E: Plots show ONL thickness of transgenic mice at 4, 16, and 28 weeks of age. B, D, F: Histograms show the average ONL thickness in the three age groups.
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f5: Quantification of morphological changes. The quantification of morphological changes are shown by measurements of outer nuclear layer (ONL) thickness along the vertical meridian of the eye in Fat1+/VPP+, Fat1–/VPP+, Fat1+/VPP–, and Fat1–/VPP– mice maintained in 20 lx cyclic light (n=10). A, C, E: Plots show ONL thickness of transgenic mice at 4, 16, and 28 weeks of age. B, D, F: Histograms show the average ONL thickness in the three age groups.

Mentions: The progression of retinal degeneration along the vertical meridian with increasing age was quantified in the “spider” graph in Figure 5A,C,E (n=10). There was a significant reduction in ONL thickness in both inferior and superior regions of both groups of four-week-old VPP+ mice (Figure 5A). Means of ONL thickness taken from 14 sites along the vertical meridian (seven superior and seven inferior of the optic nerve head) were averaged for each age group. There were no significant differences in ONL thickness between Fat1+/VPP+ and Fat1–/VPP+ or between Fat1+/VPP– and Fat1–/VPP– mice at the three ages examined (Figure 5B,D,E). There was an age-related loss of rod nuclei in all groups, which was significantly greater in the VPP+ mice. However, there was no significant effect of retinal 22:6n3 levels on the rate of rod photoreceptor degeneration.


High levels of retinal docosahexaenoic acid do not protect photoreceptor degeneration in VPP transgenic mice.

Li F, Marchette LD, Brush RS, Elliott MH, Davis KR, Anderson AG, Anderson RE - Mol. Vis. (2010)

Quantification of morphological changes. The quantification of morphological changes are shown by measurements of outer nuclear layer (ONL) thickness along the vertical meridian of the eye in Fat1+/VPP+, Fat1–/VPP+, Fat1+/VPP–, and Fat1–/VPP– mice maintained in 20 lx cyclic light (n=10). A, C, E: Plots show ONL thickness of transgenic mice at 4, 16, and 28 weeks of age. B, D, F: Histograms show the average ONL thickness in the three age groups.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927381&req=5

f5: Quantification of morphological changes. The quantification of morphological changes are shown by measurements of outer nuclear layer (ONL) thickness along the vertical meridian of the eye in Fat1+/VPP+, Fat1–/VPP+, Fat1+/VPP–, and Fat1–/VPP– mice maintained in 20 lx cyclic light (n=10). A, C, E: Plots show ONL thickness of transgenic mice at 4, 16, and 28 weeks of age. B, D, F: Histograms show the average ONL thickness in the three age groups.
Mentions: The progression of retinal degeneration along the vertical meridian with increasing age was quantified in the “spider” graph in Figure 5A,C,E (n=10). There was a significant reduction in ONL thickness in both inferior and superior regions of both groups of four-week-old VPP+ mice (Figure 5A). Means of ONL thickness taken from 14 sites along the vertical meridian (seven superior and seven inferior of the optic nerve head) were averaged for each age group. There were no significant differences in ONL thickness between Fat1+/VPP+ and Fat1–/VPP+ or between Fat1+/VPP– and Fat1–/VPP– mice at the three ages examined (Figure 5B,D,E). There was an age-related loss of rod nuclei in all groups, which was significantly greater in the VPP+ mice. However, there was no significant effect of retinal 22:6n3 levels on the rate of rod photoreceptor degeneration.

Bottom Line: Offspring were genotyped and four groups identified: Fat1(+)/VPP(+), Fat1(-)/VPP(+), Fat1(+)/VPP(-), and Fat1(-)/VPP(-).Dams were maintained on the SFO diet during the nursing period and offspring were kept on the SFO diet after weaning.There were no significant differences in outer nuclear layer thickness or ERG amplitudes between Fat1(+)/VPP(+) and Fat1(-)/VPP(+), or between Fat1(+)/VPP(-)and Fat1(-)/VPP(-) mice at any of the three ages.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.

ABSTRACT

Purpose: To determine whether docosahexaenoic acid can protect against hereditary retinal degenerations in transgenic mice expressing the V20G, P23H, and P27L (VPP) rhodopsin mutations.

Methods: Female transgenic mice expressing the VPP rhodopsin mutation, known to cause a retinal degeneration, were bred to male transgenic mice expressing the fat-1 gene, which can convert n6 to n3 polyunsaturated fatty acids (PUFA). Several weeks before breeding, the female mice were fed a standard diet containing 10% safflower oil (SFO), which is high in n6 and low in n3 PUFA (n6/n3=273). Offspring were genotyped and four groups identified: Fat1(+)/VPP(+), Fat1(-)/VPP(+), Fat1(+)/VPP(-), and Fat1(-)/VPP(-). Dams were maintained on the SFO diet during the nursing period and offspring were kept on the SFO diet after weaning. At 4, 16, and 28 weeks of age, retinal function was evaluated by electroretinography (ERG), photoreceptor cell loss was quantified by measuring outer nuclear layer thickness, and rhodopsin levels were determined. Fatty acid profiles were analyzed in whole retina, plasma, and liver at 4 and 28 weeks of age.

Results: Expression of fat-1 in the absence of dietary n3 PUFA led to the generation of two groups of mice with distinctly different levels of n3 and n6 PUFA in the three tissues that were analyzed. Already at four weeks of age, the retinas of fat-1 positive animals had higher levels of n3 PUFA than their wild-type counterparts (23%-29% versus 6.4%-6.5%). In addition, by four weeks of age, there was a significant loss of rod photoreceptor cells in the VPP mice. Progression of retinal degeneration occurred with increasing age in VPP positive mice, with photoreceptor cell death occurring in both inferior and superior regions. Amplitudes of the a- and b-waves of the ERG were significantly reduced with age, with VPP positive mice showing the greatest change. Rhodopsin content was lower in the VPP transgenic mice. There were no significant differences in outer nuclear layer thickness or ERG amplitudes between Fat1(+)/VPP(+) and Fat1(-)/VPP(+), or between Fat1(+)/VPP(-)and Fat1(-)/VPP(-) mice at any of the three ages.

Conclusions: High levels of retinal docosahexaenoic acid do not protect mice expressing the VPP rhodopsin mutation from retinal degeneration.

Show MeSH
Related in: MedlinePlus