Kumquat Fruit Administration Counteracts Dysmetabolism-Related Neurodegeneration and the Associated Brain Insulin Resistance in the High-Fat Diet-Fed Mice

Abstract

Metabolic disorders and brain insulin resistance (IR) are major risk factors for the development of neurodegenerative conditions. Kumquat fruit (KF) administration has demonstrated significant anti-dysmetabolic effects, improving peripheral IR in murine models of metabolic syndrome. Along these lines, this study evaluated the neuroprotective effects of KF supplementation in a model of dysmetabolism-induced neuronal damage and its ability to counteract the disruption of brain insulin signalling. To this end, biochemical and histological analysis assessed neuroapoptosis, disruption of brain insulin signalling and neuroinflammation in a model of high-fat diet (HFD)-induced neuronal damage. Our findings demonstrate, for the first time, that KF supplementation significantly counteracts HFD-induced neuroapoptosis downregulating pro-apoptotic genes (FAS-L, BIM and P27) and upregulating the anti-apoptotic ones (BDNF and BCL-2). Coherently, KF positively influenced the expression of selected genes related to Alzheimer's Disease. Relevantly, these effects were associated to KF ability to restore brain insulin signalling by increasing insulin receptor expression, reducing IRS-1 serine phosphorylation, enhancing both AKT activation and GSK-3 beta inactivation. Accordingly, KF suppressed HFD-neuroinflammation, counteracting the overexpression of NF-kappa B and its downstream enzymatic products, iNOS and COX-2. Collectively, these findings demonstrate the neuroprotective benefits of KF administration, supporting its potential as a dietary intervention for dysmetabolic-related neurodegenerative disorders.