摘要：SummaryInnate defensive responses, unlearned behaviors improving individuals’ chances of survival, have been found to involve the dopamine (DA) system. In the superior colliculus (SC), known for its role in defensive behaviors to visual threats, neurons expressing dopaminergic receptors of type 1 (Drd1+) and of type 2 (Drd2+) have been identified. We hypothesized that SC neurons expressing dopaminergic receptors may play a role in promoting innate defensive responses. Optogenetic activation of SC Drd2+ neurons, but not Drd1+ neurons, triggered defensive behaviors. Chemogenetic inhibition of SC Drd2+ neurons decreased looming-induced defensive behaviors, as well as pretreatment with the pharmacological Drd2+ agonist quinpirole, suggesting an essential role of Drd2 receptors in the regulation of innate defensive behavior. Input and output viral tracing revealed SC Drd2+ neurons mainly receive moderate inputs from the locus coeruleus (LC). Our results suggest a sophisticated regulatory role of DA and its receptor system in innate defensive behavior.Graphical abstractDisplay OmittedHighlights•Optogenetic activation of SC Drd2 + neurons, but not Drd1 + , induces defensive behaviors•Repeated activation of SC Drd2 + provokes aversive memory and depression-like behavior•Chemogenetic and pharmacological inhibition of SC Drd2 + impaired defensive behaviors•Monosynaptic tracing revealed SC Drd2 + neurons mainly receive TH + projections from LCBiological sciences; Molecular neuroscience; Neuroscience
