Fluoxetine Ameliorates Cognitive Deficits in High-Fat Diet Mice by Regulating BDNF Expression

High-fat diet (HFD) induced obesity is associated with depression-related behavioral and neurogenic changes and may lead to cognitive impairment. Fluoxetine (FXT), the most commonly used antidepressant, may alleviate depressive symptoms by increasing neurogenesis, but the potential efficacy of FXT for HFD-induced cognitive deficits is unclear. In this study, we established an obese HFD mouse model by feeding three-week-old male C57BL/6N mice with a chronic HFD for 18 weeks, then assessed adipose tissue morphology by magnetic resonance imaging and histopathology, assessed cognitive function by Morris water maze and novel object recognition tests, and detected DCX⁺ and BrdU⁺ expression in the hippocampal dentate gyrus (DG) region by immunofluorescence bioassay. Western blot detected brain-derived neurotrophic factor (BDNF) levels and CREB-BDNF pathway-related genes were assayed by Quantitative RT-PCR. The results of the study showed that HFD contributes to obesity and cognitive deficits, and more importantly, it also reduces BDNF expression and neurogenesis levels in the hippocampus. Subsequently, we found that treatment with FXT (10 mg/kg/day) ameliorated chronic HFD-induced cognitive deficits and increased the expression of Nestin, BrdU⁺, and DCX⁺ in the DG, restored BDNF expression in the hippocampus and increased the expression of genes related to CREB, BDNF, NGF, and MAPK1. In conclusion, our data elucidated that FXT ameliorates cognitive deficits and reduces chronic HFD-induced neurogenesis by restoring BDNF expression and CREB-BDNF signaling, this provides a good basis and scientific significance for future research on the clinical treatment of obesity.