Mice produce interneurons in the septum as a response to aversive experiences and antidepressant treatment.

Abstract

Adult neurogenesis sustains olfactory function, facilitates the acquisition of new memories, and provides resilience against depression in mice. Neural stem cells (NSCs) elicit selective responses to different physiological and pathological stimuli, thereby modulating neuron production. Here, we show that fear conditioning stimulates neurogenesis in the adult mouse brain septum by activating NSCs in the dorsal septum (dsNSCs) situated near a plexus of serotonergic axons originating from raphe nucleus neurons-key regulators of mood, anxiety, and stress responses. Elevation of serotonin (5HT) levels with the antidepressant and anxiolytic drug fluoxetine similarly promoted dsNSC proliferation and neurogenesis. The adult-born GABAergic interneurons integrate into septal nuclei. These findings suggest a potential adaptive response in mice to stress-inducing aversive experiences and elevated 5HT in the adult septum.