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Longitudinal study of the effects of a high-fat diet on glucose regulation, hippocampal function, and cerebral insulin sensitivity in C57BL/6 mice.
Mielke JG, Nicolitch K, Avellaneda V, Earlam K, Ahuja T, Mealing G, Messier C.
Behav Brain Res. 2006 Dec 15;175(2):374-82. Epub 2006 Nov 1
Neurobiology
Program, Institute for Biological Sciences, National Research Council of Canada, 1200 Montreal Road, Building M-54, Ottawa, Ont., Canada
Although the increasing rate of obesity has stimulated
interest in the effects of diet composition on peripheral
systems, comparatively little work has been done to examine
effects upon the brain. A diet high in fat is one of many
factors that can promote obesity, and previous research has
shown that such a diet can produce learning and memory
impairment in rodents. In the present study, C57BL/6 mice were
placed on either a high-fat (45% kcal fat) or regular (5% kcal
fat) diet, and examined at different points during the
subsequent year. The high-fat diet led to increased weight
gain, significant impairment in glucoregulation, and altered
insulin-mediated signaling within the hippocampus, an area of
the brain believed to be important for the acquisition of
memory. Following ten months on either diet, synaptic function
in ex vivo hippocampal slices was examined, and neither
stimulus-response curves nor electrically induced long-term
potentiation were found to be different. As well, performance
in the Morris water maze, a hippocampal-dependent test of
spatial memory, was not influenced by diet. However, mice
consuming a high-fat diet failed to perform an operant
bar-pressing task, indicating a significant impairment to
procedural learning and consolidation processes. Despite
causing broad peripheral changes in C57BL/6 mice, consuming a
large proportion of calories from saturated fat had only a
limited effect upon learning and memory, which suggests that
certain aspects of brain function are selectively vulnerable
to the influences of diet.
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