Chemogenetic activation of oxytocinergic neurons modulates acute neuroinflammation and improves brain development after pediatric traumatic brain injury

OBJECTIVE: Pediatric traumatic brain injury (TBI) is a leading cause of death and disability in infants, whose neurodevelopmental consequences currently lack effective treatment. Since TBI is associated with neuroinflammation, modulation of the post-injury neuroinflammatory response is a promising strategy. Oxytocin is suggested to possess anti-inflammatory properties, and seems to play a role in clinical interventions that improve brain development in neonates. However, the underlying mechanisms remain unclear, as does its applicability to acute brain injury. METHODS: Here, we assess the effects of chemogenetic activation of oxytocinergic neurons on acute neuroinflammation and on long-term brain development after TBI in postnatal day 7 (P7) male mice. Immunohistochemistry, RNA sequencing, ex-vivo MRI-diffusion tensor imaging, in-vivo functional ultrasound imaging and behavioral assays are used for assessment. Oxytocinergic neurons were chemogenetically activated daily between P7 and P10. RESULTS: We show that chemogenetic activation of oxytocinergic neurons mitigates the acute neuroinflammatory response to TBI 24 h post-injury, where it reduces the expression of inflammation-related genes, and promotes brain repair and development gene pathways in microglia. In the long-term, early-life oxytocinergic neuron activation improves subcortical and cortical white matter damage after TBI, prevents hyperactivity and loss of social behavior, and restores TBI-induced alterations in resting-state functional connectivity of the isocortex. These effects were found 35 days after the last treatment session. CONCLUSIONS: Our findings enhance the understanding of neuroinflammation modulation by oxytocin, reveal its long-term effects, and support intervention associated with endogenous oxytocin release as a promising neuroprotective strategy in pediatric TBI.