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.