International Journal of Molecular Sciences Article Neural Stem Cell-Derived Exosomes Revert HFD-Dependent Memory Impairment via CREB-BDNF Signalling Matteo Spinelli 1, Francesca Natale 1,2, Marco Rinaudo 1, Lucia Leone 1,2, Daniele Mezzogori 1, Salvatore Fusco 1,2,* and Claudio Grassi 1,2 1 Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168 Rome, Italy;
[email protected] (M.S.);
[email protected] (F.N.);
[email protected] (M.R.);
[email protected] (L.L.);
[email protected] (D.M.);
[email protected] (C.G.) 2 Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy * Correspondence:
[email protected] Received: 6 October 2020; Accepted: 25 November 2020; Published: 26 November 2020 Abstract: Overnutrition and metabolic disorders impair cognitive functions through molecular mechanisms still poorly understood. In mice fed with a high fat diet (HFD) we analysed the expression of synaptic plasticity-related genes and the activation of cAMP response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signalling. We found that a HFD inhibited both CREB phosphorylation and the expression of a set of CREB target genes in the hippocampus. The intranasal administration of neural stem cell (NSC)-derived exosomes (exo-NSC) epigenetically restored the transcription of Bdnf, nNOS, Sirt1, Egr3, and RelA genes by inducing the recruitment of CREB on their regulatory sequences. Finally, exo-NSC administration rescued both BDNF signalling and memory in HFD mice. Collectively, our findings highlight novel mechanisms underlying HFD-related memory impairment and provide evidence of the potential therapeutic effect of exo-NSC against metabolic disease-related cognitive decline.