Intranasal interferon-beta alleviates anxiety and depressive-like behaviors by modulating microglia polarization in an Alzheimer's disease model

•APP overexpression in the hippocampus induced anxiety-like behaviors in rats.•APP overexpression in the hippocampus induced depressive-like behaviors in rats.•Psychiatric symptoms were accompanied with changes in expression of M1/M2 markers.•IFNβ improved anxious/depressive-like behaviors in AD rats.•IFNβ shifted microglia phenotype from M1 to M2 in the hippocampus of AD rats.