β1-adrenergic receptor activation enhances memory in Alzheimer's disease model

OBJECTIVE Deficits in social recognition and learning of social cues are major symptoms of neurodegenerative disorders such as Alzheimer's disease (AD). Here we studied the role of β1-noradrenergic signaling in cognitive function to determine whether it could be used as a potential therapeutic target for AD. METHODS Using pharmacological, biochemical and behavioral tools, we assessed social recognition and the β1-adrenergic receptor (ADR) and its downstream PKA/phospho-CREB (pCREB) signaling cascade in the medial amygdala (MeA) in Thy1-hAPPLond/Swe+(APP) mouse model of AD. RESULTS Our results demonstrated that APP mice display a significant social recognition deficit which is dependent on the β1-adrenergic system. Moreover, betaxolol, a selective β1-ADR antagonist, impaired social but not object/odor learning in C57Bl/6 mice. Our results identifies activation of the PKA/pCREB downstream of β1-ADR in MeA as responsible signaling cascade for learning of social cues in MeA. Finally, we found that xamoterol, a selective β1-ADR partial agonist, rescued the social recognition deficit of APP mice by increasing nuclear pCREB. INTERPRETATION Our data indicate that activation of β1-ADR in MeA is essential for learning of social cues, and that an impairment of this cascade in AD may contribute to pathogenesis and cognitive deficits. Therefore, selective activation of β1-ADR may be used as a therapeutic approach to rescue memory deficits in AD. Further safety and translational studies will be needed to ensure the safety of this approach.