Diets rich in saturated fat and fructose induce anxiety and depression‐like behaviours in the rat: is there a role for lipid peroxidation?

Epidemiological studies reveal associations between obesity/metabolic syndrome and mood disorders. We assessed behavioural changes in rats fed diets enriched in fat and fructose in different proportions and correlated the observed alterations with biochemical changes induced by the diets. Three groups of rats were used as follows: control (C) animals fed regular rat chow, rats fed high‐fat diet (HF) and rats fed high‐fat and high‐fructose diet (HFHF). HF and HFHF animals were also given a 10% fructose solution as drinking water. Behavioural and biochemical parameters were determined. Anxiety was measured by the open‐field and the social interaction test. Depression‐like behaviour was evaluated by the forced swimming test. The object recognition test was utilized to assess effects on memory. Diet‐exposed animals displayed signs of anxiety in the open‐field (HF rats had reduced central time; HFHF rats had reduced number of central entries) and in the social interaction test (decreased time of interaction in HF group). In the forced swimming test, the immobility time was prolonged in the HFHF group. While different measures of anxiety scores correlated with visceral adiposity and dyslipidemia, results from both social interaction and forced swimming tests were significantly associated with lipid peroxidation, which in turn also correlated with the metabolic parameters. The experimental diets did not affect the object recognition memory. Both experimental diets induced metabolic derangements in rats and provoked similar anxiety‐ and depression‐like behaviours. Lipid peroxidation seems to play a role in translating diet‐induced metabolic alterations into behavioural disorders.