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Retinal light damage in rats with altered levels of rod outer segment docosahexaenoate.
Invest Ophthalmol Vis Sci. 1996 Oct; 37(11):2243-57.IO

Abstract

PURPOSE

To compare retinal light damage in rats with either normal or reduced levels of rod outer segment (ROS) docosahexaenoic acid.

METHODS

Weanling male albino rats were maintained in a weak cyclic light environment and fed either a nonpurified control diet or a purified diet deficient in the linolenic acid precursor of docosahexaenoic acid (DHA). Half the rats on the deficient diet were given linseed oil, containing more than 50 mol% linolenic acid, once a week to maintain ROS DHA at near normal levels. Diets and linseed oil supplementation were continued for 7 to 12 weeks. To replenish DHA in their ROS, some 10-week-old rats on the deficient diet were given linseed oil three times a week for up to 3 additional weeks. Groups of animals were killed at various times for ROS fatty acid determinations or were exposed to intense green light using intermittent or hyperthermic light treatments. The extent of retinal light damage was determined biochemically by rhodopsin or photoreceptor cell DNA measurements 2 weeks after exposure and morphologically by light and electron microscopy at various times after light treatment.

RESULTS

Rats maintained for 7 to 12 weeks on the linolenic acid-deficient diet had significantly lower levels of DHA and significantly higher levels of n-6 docosapentaenoic acid (22:5n-6) in their ROS than deficient-diet animals supplemented once a week with linseed oil or those fed the nonpurified control diet. As determined by rhodopsin levels and photoreceptor cell DNA measurements, deficient diet rats exhibited protection against retinal damage from either intermittent or hyperthermic light exposure. However, the unsaturated fatty acid content of ROS from all three dietary groups was the same and greater than 60 mol%. In 10 week-old deficient-diet rats given linseed oil three times a week, ROS DHA was unchanged for the first 10 days, whereas 22:5n-6 levels declined by 50%. After 3 weeks of treatment with linseed oil, ROS DHA and 22:5n-6 were nearly the same as in rats supplemented with linseed oil from weaning. The time course of susceptibility to retinal light damage, however, was different. Hyperthermic light damage in rats given linseed oil for only 2 days was the same as for rats always fed the deficient diet. Six days after the start of linseed oil treatment, retinal light damage was the same as in rats given the linseed oil supplement from weaning. Morphologic alterations in ROS of linseed oil-supplemented rats immediately after intermittent light exposure were more extensive than in either the deficient-diet animals or those fed the control diet. The deficient-diet rats also exhibited better preservation of photoreceptor cell nuclei and structure 2 weeks after exposure.

CONCLUSIONS

Rats fed a diet deficient in the linolenic acid precursor of DHA are protected against experimental retinal light damage. The relationship between retinal light damage and ROS lipids does not depend on the total unsaturated fatty acid content of ROS; the damage appears to be related to the relative levels of DHA and 22:5n-6.

Authors+Show Affiliations

Petticrew Research Laboratory, Wright State University, Daylon, Ohio 45435, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8843911

Citation

Organisciak, D T., et al. "Retinal Light Damage in Rats With Altered Levels of Rod Outer Segment Docosahexaenoate." Investigative Ophthalmology & Visual Science, vol. 37, no. 11, 1996, pp. 2243-57.
Organisciak DT, Darrow RM, Jiang YL, et al. Retinal light damage in rats with altered levels of rod outer segment docosahexaenoate. Invest Ophthalmol Vis Sci. 1996;37(11):2243-57.
Organisciak, D. T., Darrow, R. M., Jiang, Y. L., & Blanks, J. C. (1996). Retinal light damage in rats with altered levels of rod outer segment docosahexaenoate. Investigative Ophthalmology & Visual Science, 37(11), 2243-57.
Organisciak DT, et al. Retinal Light Damage in Rats With Altered Levels of Rod Outer Segment Docosahexaenoate. Invest Ophthalmol Vis Sci. 1996;37(11):2243-57. PubMed PMID: 8843911.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Retinal light damage in rats with altered levels of rod outer segment docosahexaenoate. AU - Organisciak,D T, AU - Darrow,R M, AU - Jiang,Y L, AU - Blanks,J C, PY - 1996/10/1/pubmed PY - 1996/10/1/medline PY - 1996/10/1/entrez SP - 2243 EP - 57 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 37 IS - 11 N2 - PURPOSE: To compare retinal light damage in rats with either normal or reduced levels of rod outer segment (ROS) docosahexaenoic acid. METHODS: Weanling male albino rats were maintained in a weak cyclic light environment and fed either a nonpurified control diet or a purified diet deficient in the linolenic acid precursor of docosahexaenoic acid (DHA). Half the rats on the deficient diet were given linseed oil, containing more than 50 mol% linolenic acid, once a week to maintain ROS DHA at near normal levels. Diets and linseed oil supplementation were continued for 7 to 12 weeks. To replenish DHA in their ROS, some 10-week-old rats on the deficient diet were given linseed oil three times a week for up to 3 additional weeks. Groups of animals were killed at various times for ROS fatty acid determinations or were exposed to intense green light using intermittent or hyperthermic light treatments. The extent of retinal light damage was determined biochemically by rhodopsin or photoreceptor cell DNA measurements 2 weeks after exposure and morphologically by light and electron microscopy at various times after light treatment. RESULTS: Rats maintained for 7 to 12 weeks on the linolenic acid-deficient diet had significantly lower levels of DHA and significantly higher levels of n-6 docosapentaenoic acid (22:5n-6) in their ROS than deficient-diet animals supplemented once a week with linseed oil or those fed the nonpurified control diet. As determined by rhodopsin levels and photoreceptor cell DNA measurements, deficient diet rats exhibited protection against retinal damage from either intermittent or hyperthermic light exposure. However, the unsaturated fatty acid content of ROS from all three dietary groups was the same and greater than 60 mol%. In 10 week-old deficient-diet rats given linseed oil three times a week, ROS DHA was unchanged for the first 10 days, whereas 22:5n-6 levels declined by 50%. After 3 weeks of treatment with linseed oil, ROS DHA and 22:5n-6 were nearly the same as in rats supplemented with linseed oil from weaning. The time course of susceptibility to retinal light damage, however, was different. Hyperthermic light damage in rats given linseed oil for only 2 days was the same as for rats always fed the deficient diet. Six days after the start of linseed oil treatment, retinal light damage was the same as in rats given the linseed oil supplement from weaning. Morphologic alterations in ROS of linseed oil-supplemented rats immediately after intermittent light exposure were more extensive than in either the deficient-diet animals or those fed the control diet. The deficient-diet rats also exhibited better preservation of photoreceptor cell nuclei and structure 2 weeks after exposure. CONCLUSIONS: Rats fed a diet deficient in the linolenic acid precursor of DHA are protected against experimental retinal light damage. The relationship between retinal light damage and ROS lipids does not depend on the total unsaturated fatty acid content of ROS; the damage appears to be related to the relative levels of DHA and 22:5n-6. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/8843911/Retinal_light_damage_in_rats_with_altered_levels_of_rod_outer_segment_docosahexaenoate_ L2 - https://iovs.arvojournals.org/article.aspx?volume=37&issue=11&page=2243 DB - PRIME DP - Unbound Medicine ER -