Environmental novelty activates β₂-adrenergic signaling to prevent the impairment of hippocampal LTP by Aβ oligomers

A central question about human brain aging is whether cognitive enrichment slows the development of Alzheimer changes. Here, we show that prolonged exposure to an enriched environment (EE) facilitated signaling in the hippocampus of wildtype mice that promoted long-term potentiation. A key feature of the EE effect was activation of β₂-adrenergic receptors and downstream cAMP/ PKA signaling. This EE pathway prevented LTP inhibition by soluble oligomers of amyloid b-protein (Aβ) isolated from AD cortex. Protection by EE occurred in both young and middle-aged wild-type mice. Exposure to novelty afforded greater protection than did aerobic exercise. Mice chronically fed a β-adrenergic agonist without EE were protected from hippocampal impairment by Aβ oligomers. Thus, EE enhances hippocampal synaptic plasticity by activating β-adrenoceptor signaling and mitigating synaptotoxicity of human Aβ oligomers. These mechanistic insights support using prolonged exposure to cognitive novelty and/or oral b-adrenergic agonists to lessen the effects of Aβ accumulation during aging