Vitamin D prevents cognitive decline and enhances hippocampal synaptic function in aging rats
PNAS
Caitlin S. Latimera,1, Lawrence D. Brewera, James L. Searcya,2, Kuey-Chu Chena, Jelena Popovića, Susan D. Kranerb, Olivier Thibaulta, Eric M. Blalocka, Philip W. Landfielda, and Nada M. Portera, nadap@uky.edu
1Present address: Department of Anatomic Pathology, University of Washington, Seattle, WA 98195.
2Present address: Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, United Kingdom.
Edited* by Hector F. DeLuca, University of Wisconsin–Madison, Madison, WI, and approved August 26, 2014 (received for review March 10, 2014)
10,000 IU of vitamin D / kilogram of feed ==> 30 ng in blood (similar level to humans)
Aging rats with 30 ng of Vitamin D performed the reversal task much more quickly
Aging rats with 30 ng of Vitamin D had stronger nerve responses
See also VitaminDWiki
- Overview Alzheimer's-Cognition and Vitamin D
- Cognition and vitamin D – summary of expert opinions – July 2014
- Vitamin D reduces Alzheimer’s disease in at least 11 ways – Jan 2013
- Cognitive category listing with associated searches
Vitamin D Council has a good description of this experiment - behind a paywall
Significance
Higher blood levels of vitamin D are associated with better health outcomes. Vitamin D deficiency, however, is common among the elderly. Despite targets in the brain, little is known about how vitamin D affects cognitive function. In aging rodents, we modeled human serum vitamin D levels ranging from deficient to sufficient and tested whether increasing dietary vitamin D could maintain or improve cognitive function. Treatment was initiated at middle age, when markers of aging emerge, and maintained for ∼6 mo. Compared with low- or normal-dietary vitamin D groups, only aging rats on higher vitamin D could perform a complex memory task and had blood levels considered in the optimal range. These results suggest that vitamin D may improve the likelihood of healthy cognitive aging.
Abstract
Vitamin D is an important calcium-regulating hormone with diverse functions in numerous tissues, including the brain. Increasing evidence suggests that vitamin D may play a role in maintaining cognitive function and that vitamin D deficiency may accelerate age-related cognitive decline. Using aging rodents, we attempted to model the range of human serum vitamin D levels, from deficient to sufficient, to test whether vitamin D could preserve or improve cognitive function with aging. For 5–6 mo, middle-aged F344 rats were fed diets containing low, medium (typical amount), or high (100, 1,000, or 10,000 international units/kg diet, respectively) vitamin D3, and hippocampal-dependent learning and memory were then tested in the Morris water maze. Rats on high vitamin D achieved the highest blood levels (in the sufficient range) and significantly outperformed low and medium groups on maze reversal, a particularly challenging task that detects more subtle changes in memory. In addition to calcium-related processes, hippocampal gene expression microarrays identified pathways pertaining to synaptic transmission, cell communication, and G protein function as being up-regulated with high vitamin D. Basal synaptic transmission also was enhanced, corroborating observed effects on gene expression and learning and memory. Our studies demonstrate a causal relationship between vitamin D status and cognitive function, and they suggest that vitamin D-mediated changes in hippocampal gene expression may improve the likelihood of successful brain aging.