Fructose Intake Impairs Cortical Antioxidant Defenses Allied to Hyperlocomotion in Middle-Aged C57BL/6 Female Mice

Recent evidence suggests that young rodents submitted to high fructose (FRU) diet develop metabolic, and cognitive dysfunctions. However, it remains unclear whether these detrimental effects of FRU intake can also be observed in middle-aged mice. Nine months-old C57BL/6 female mice were fed with water (Control) or 10% FRU in drinking water during 12 weeks. After that, metabolic, and neurochemical alterations were evaluated, focusing on neurotransmitters, and antioxidant defenses. Behavioral parameters related to motor activity, memory, anxiety, and depression were also evaluated. Mice consuming FRU diet displayed increased water, and caloric intake, resulting in weight gain, which was partially compensated due to decreased food pellet intake. FRU fed animals displayed increased plasma glucose, and cholesterol levels, which was not observed in overnight-fasted animals. Superoxide dismutase (SOD), and catalase (CAT) activities were markedly decreased in the prefrontal cortex of animals receiving FRU diet, while glutathione peroxidase (GPx) slightly increased. Liver (lower GPx), striatum (higher SOD and lower CAT), and hippocampus (no changes) were less impacted. No changes were observed in glutathione reductase, and thioredoxin reductase activities, two ancillary enzymes for peroxide detoxification. FRU intake did not alter serotonin, dopamine, and norepinephrine levels in the hippocampus, prefrontal cortex, and striatum. No significant alterations were observed in working, and short-term spatial memory; and in anxiety- and depressive-like behaviors in animals treated with FRU. Increased locomotor activity was observed in FRU-fed middle-aged mice, as evaluated in the open field, elevated plus-maze, Y maze, and object location tasks. Overall, these results demonstrate that high FRU consumption can disturb antioxidant defenses, and increase locomotor activity in middle-aged mice, open the opportunity for further studies to address the underlying mechanisms related to these findings.