Retardation of the ageing process in collagen fibres from the tail tendon of the old hypophysectomized rat.
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Biomedical subjects
Publications and source records attributed to A V Everitt.
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Hypophysectomy in young male Wistar rats aged 70 days, like food restriction begun at the same age, retarded the life-long rate of collagen aging in tail tendon fibres and inhibited the development of age-associated proteinuria and renal histopathology. Hypothalamic lesions which increased the food intake of hypophysectomized rats from 7 g to 15 g/day and produced obesity did not alter the rate of either collagen aging or proteinuria development, nor reduce life expectancy, but increased the incidence of abnormal glomeruli. In the intact rats elevation of food intake from 7 g to 15 g/day increased the rate of proteinuria development, but did not affect the rate of collagen aging. Hypophysectomy was found to have a greater anti-collagen aging effect than food restriction, when food intakes were the same in both groups. These studies suggest a pituitary-hormonal effect on collagen aging and a food-pituitary-hormone-mediated effect on the development of age-associated proteinuria.
Two groups of aged rats, a dietary restricted group fed approximately 10 g per day from 6 weeks of age and a group fed ad lib throughout their life span, were compared with a young adult group on an 8-arm radial maze and a flavor memory task. The young adult displayed efficient performance on the radial-arm maze within the 15 day test period. In contrast, both aged groups exhibited significantly poorer performance in the maze in comparison with the young adult group neither aged group differed from chance at the end of the 15 days. The flavor memory task required the animals to consume a novel flavor. Their loss of neophobia, as indexed by their subsequent consumption, was then taken as an indication of the extent to which they remembered the novel flavor and its effects. The young adult group lost their neophobia more rapidly than either of the aged groups, which did not appear to differ from each other. Taken together, this pattern of results indicates that dietary restriction does not protect animals from the memory loss observed in aged animals.
The development of age-associated proteinuria and renal disease was studied in groups of male Wistar rats fed 12.5, 25, 50 and 75 kcal of food/day, respectively, and in calorie-restricted (40 kcal/day) rats receiving diets rich in fat, protein or carbohydrate. Proteinuria developed faster, kidneys were larger and the incidence of glomerular lesions and proteinaceous casts was greater in rats eating high calorie diets of 50 kcal/day or more. High protein diets, even when calorie-restricted, increased protein excretion and the incidence of glomerular lesions. In old rats acute food restriction (25 kcal/day) decreased protein excretion by 40% in 1 week, with no further reduction in the 2 week. Life duration was greatest in rats fed 50 kcal/day.