Scopolamine affects fear learning and social recognition in adult zebrafish

Scopolamine is the secondary metabolite of the Datura stramonium and act as a muscarinic receptor antagonist. Previous studies showed that scopolamine caused attention and memory deficit. However, the effects of scopolamine on specific cognitive functions, such as fear learning and social recognition, remain poorly understood. Here, we demonstrate the effects of scopolamine on fear learning, social memory, and neural activity in zebrafish, providing a novel perspective on its impact on cognitive and social behaviors. Here, we used equal number of male and female zebrafish as an animal model and performed a series of behavioral tests after treatment with scopolamine (100 µM and 200 µM) for 1 h to evaluate social and cognitive functions. Treatment with scopolamine increased locomotion activity, reduced the level of anxiety in the novel tank diving test, and impaired memory retrieval in the active avoidance test. Scopolamine also increased the preference for newly introduced fish in the social recognition test. In situ hybridization of c-fos mRNA showed that scopolamine decreased the neural activity of the telencephalic regions that are crucial for social, cognitive, and memory functions. Our results demonstrate the effects of scopolamine on fear learning and social recognition in adult zebrafish.