The effect of life-long 60% ad lib food restriction on performance in two tasks involving spatial memory, the eight-arm radial maze and the Morris water maze, was studied in young and aged Fischer 344 rats. Restricted (R) and ad lib (AL) feeding groups were compared at 8, 16, and 24 months of age on both tasks. A 30-month-old R group was also tested in the Morris water maze. In the eight-arm maze, although 24-month-old animals performed more poorly than 8- and 16-month-old animals during the first week of testing, overall accuracy of performance did not vary significantly as a function of age. Twenty-four-month-old animals took longer to make 10 choices than did younger animals, and there was a significant interaction between feeding regimen and age, reflecting the fact that at the two younger ages, R groups performed more quickly than the AL groups. In the Morris water maze, both distance swum and time to find the platform increased with age. Life-long food restriction led to small but significant improvements in performance in the water maze in aged rats. R groups showed evidence for better retention over 24-hour intervals than did AL groups. By 30 months of age, however, R animals showed impaired performance relative to younger R groups. These differential findings on the two tasks, as they were used here, suggest that there was greater impairment with age on the spatial memory task requiring retention of information over long intervals than there was on the task primarily involving working memory within a trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMedDate not supplied

Effects of copper and histidine on oxidative modification of low density lipoprotein and its subsequent binding to collagen.

It was previously shown that serum low density lipoprotein (LDL) binds to type I collagen gels and that the binding is increased after modification by cultured endothelial cells. It is now demonstrated that when LDL is incubated with cells cultured in Dulbecco's modified minimal essential medium (DMEM), the subsequent binding of LDL to collagen is considerably less than after incubation with endothelial cells cultured in Ham's F-12 medium (F12). To determine the reason for this difference, collagen gels were made with saline containing ingredients of DMEM individually or in groups, and binding of LDL to such gels was measured. Modification of LDL, manifested by a high level of binding to the collagen, by lipid peroxidation (production of thiobarbituric acid-reactive substances), and by increased electrophoretic mobility occurred on exposure to collagen gels made in saline; these changes were almost completely inhibited by the addition of histidine at a concentration equal to that in DMEM. They were also inhibited by butylated hydroxytoluene, desferrioxamine, and EDTA; penicillamine and hydroxyl-radical scavengers inhibited collagen binding but did not inhibit lipid peroxidation or the increase in electrophoretic mobility. Nominally, DMEM contains 270 microM histidine but no copper, whereas F12 contains 135 microM histidine and 10 nM copper; addition of copper (as much as 5 microM) to DMEM or of histidine (as much as 2.16 mM) to F12 did not overcome the differences between the media in supporting LDL oxidation by endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗