Effects of long-term vitamin K (phylloquinone) intake on retina aging.
Emerging evidence suggests neuroprotective functions of vitamin K and/or vitamin K-dependent proteins. We investigated the effect of dietary vitamin K on retina aging (thinning). Female Sprague-Dawley rats were maintained from weaning on low (80 microg kg(-1) diet), adequate (500 microg kg(-1) diet) or high (2000 microg kg(-1) diet) levels of vitamin K1 (phylloquinone). Relative concentrations of brain vitamin K associated with these diets were 1: 3.3: 25 (K1) and 1: 2.7: 9.0 (menaquinone-4). Histomorphometry of old (21 month) rats revealed positive associations between vitamin K and thickness of retina layers, especially in the equatorial/peripheral retina. No association of diet and retina thickness was detected among young (6 month) animals. The sparing effect of vitamin K in the retina was most evident in the inner plexiform layer and in the photoreceptor inner and outer segments. Surprisingly, we observed no effect of vitamin K on the age-dependent loss of photoreceptor cells, interneurons or ganglion cells. These data suggest a role for vitamin K in maintaining the aging retina and suggest that the sparing effect of vitamin K does not reflect the survival-promoting (anti-apoptotic) activities of vitamin K-dependent proteins.
Carrié
Isabelle
I
Department of Nutrition, Université de Montréal, Montréal, Qué., Canada H3C 3J7.
Ferland
Guylaine
G
Obin
Martin S
MS
D000375:Aging / Q000502:physiology*; D000818:Animals; D001923:Brain Chemistry; D002452:Cell Count; D004032:Diet; D005260:Female; D009474:Neurons / Q000166:cytology; D009752:Nutritional Status; D010786:Photoreceptor Cells / Q000166:cytology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology*; D010837:Vitamin K 1 / Q000008:administration & dosage* / Q000032:analysis; D024482:Vitamin K 2 / Q000031:analogs & derivatives* / Q000032:analysis
D024482:Vitamin K 2; C030814:menatetrenone; D010837:Vitamin K 1