Vitamin D mitigates age-related cognitive decline through the modulation of pro-inflammatory state and decrease in amyloid burden

Background: increasing evidence shows an association between the use of vitamin d and improvement in age-related cognitive decline. in this study,we investigated the possible mechanisms involved in the neuroprotective effects of vitamin d on age-related brain changes and cognitive function.methods: male f344 rats aged 20 months (old) and 6 months (young) were used and randomly assigned to either vitamin d supplementation or no supplementation (control). a total of n = 39 rats were used in the study. rats were individually housed and the supplementation group received a subcutaneous injection of vitamin d (1,α25-dihydroxyvitamin d3) 42 i.u./kg for 21 days. control animals received equal volume of normal saline. behavioral testing in water maze and spontaneous object recognition tasks started on day 14. levels of interleukin (il)-1β and il-10 were quantified to assess inflammatory state. also,beta amyloid (aβ) clearance and aβ load were measured.results: our results show that: (1) aged rats demonstrated significant learning and memory impairment overall compared to younger animals. however,the age-related decline in learning and memory was ameliorated by the supplementation of vitamin d. no vitamin d effect on learning and memory was seen in the young animals; 2) the pro-inflammatory cytokine il-1β is significantly increased while the anti-inflammatory cytokine il-10 is significantly decreased in the aged rats compared to the young animals; but this age-related change in inflammatory state was mitigated by vitamin d supplementation. no effects of vitamin d were seen on the il-1β and il-10 expression in the young rats; (3) vitamin d increased aβ clearance and decreased amyloid burden in the aged rats while no significant difference was seen between the young animal groups.conclusions: our data suggest that vitamin d supplementation modulated age-related increase in pro-inflammatory state and amyloid burden. it is possible that these effects of vitamin d mediated the decrease memory impairment seen in the aged rats making it a useful therapeutic option to alleviate the effects of aging on cognitive function. © 2012 briones and darwish; licensee biomed central ltd.