TITLE:
Fructose-Induced Cognitive Dysfunction Is Associated with Increased Oxidative Stress in the Rat Brains
AUTHORS:
En Yabe, Shoko Yamakawa, Hiroe Sakuyama Tomari, Yuri Kintaka, Yoshio Uehara
KEYWORDS:
Fructose, Cognitive Function, Type 2 Diabetes, Dahl Rat
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.6 No.10,
October
26,
2018
ABSTRACT: High
fructose consumption is a risk factor for diabetes. Type 2 diabetes is associated
with cognitive and memory impairment. To determine if fructose intake might
affect memory function independently of diabetes development, we investigated
the effects of monosaccharides on memory in prediabetic state. We examined
whether 2.5% apple juice solution could influence cognitive function in
salt-sensitive Dahl rats using passive avoidance methods. Furthermore, we
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. These
findings suggest that long-term apple juice consumption decreases memory
function, possibly through an increase in oxidative stress in the brain, in
turn induced by fructose overloading. Fructose-induced cognitive dysfunction is
likely mediated by mechanisms other than insulin resistance.