Fructose-Induced Cognitive Dysfunction Is Associated with Increased Oxidative Stress in the Rat Brains
Evidence is emerging that obesity and
type 2 diabetes are often associated with cognitive impairment. Fructose, or
fruit sugar, is a simple ketonic monosaccharide found in many plants. Recent studies have reported a role of excessive fructose intake in
the onset of type 2 diabetes in rodents and humans.
To determine if
fructose intake might affect memory function independently of diabetes
development, the authors in this paper investigated the effects of
monosaccharides on memory in prediabetic state. They examined whether 2.5%
apple juice solution could influence cognitive function in salt-sensitive Dahl
rats using passive avoidance methods. Furthermore, the authors examined the
role of monosaccharides intake in cognitive function and oxidative stress in
the brain.
Four-week
consumption of either apple juice or 2.5% fructose did not affect the blood
glucose concentrations; however, apple juice, but not fructose, significantly
decreased cognitive function compared with that of control rats given water.
Second, Wistar rats aged 4 weeks were assigned to four groups given water, or
1.25% glucose, or fructose, or galactose solutions for 11 weeks. The fructose
group had only slightly higher blood glucose concentrations than the control
group. However, memory function engraved at age of 7 weeks and evaluated for 8
weeks in a passive avoidance test, was significantly decreased in the fructose
and galactose groups compared with those in the glucose group. Oxidative stress
in the brain, assessed by the tissue malondialdehyde (MDA) content, was
significantly increased in the fructose group compared with that in the control
group, and the decrease in cognitive function significantly correlated with the
MDA content.
In conclusion, these
findings demonstrate that long-term fructose intake is associated with impaired
memory function and increased oxidative stress in the rat brain. Memory was
also impaired in rats given apple juice rich in fructose, without overt
hyperglycemia. These results suggest that fructose-intake-associated memory
impairment is not related to insulin resistance but, rather, is caused by
fructose loading per se. Fructose intake may need to be reduced to the minimum
level required for healthy living.
Article by En
Yabe, et al, from Japan.
Full access: http://mrw.so/4N3j0h
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