Hippocampal cAMP regulates HCN channel function on two time scales with differential effects on animal behavior

Hyperpolarization-activated cyclic nucleotide–gated (HCN) channels regulate neuronal excitability and represent a possible therapeutic target for major depressive disorder (MDD). These channels are regulated by intracellular cyclic adenosine monophosphate (cAMP). However, the relationship between cAMP signaling and the influence of HCN channels on behavior remains opaque. In this study, we investigated the role of hippocampal cAMP signaling on behavior using chemogenetic technology in mice. Acutely increasing cAMP limited spatial memory and motivated behavior by increasing HCN function. However, chronically elevated cAMP limited surface trafficking of HCN channels by disrupting the interaction between HCN and tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b), an auxiliary subunit. Chronically increased cAMP in the dorsal hippocampus was also sufficient to rescue cognitive deficits induced by chronic stress in mice. These results reveal a behaviorally relevant form of regulation of HCN channel surface expression that has potential as a therapeutic target for cognitive deficits related to chronic stress.