Preterm birth is associated with dystonic features and reduced cortical parvalbumin immunoreactivity in mice.

Background: Preterm birth is a common cause of dystonia. Though dystonia is often associated with striatal dysfunction after neonatal brain injury, cortical dysfunction may best predict dystonia following preterm birth. Furthermore, abnormal sensorimotor cortex inhibition is associated with genetic and idiopathic dystonias. To investigate cortical dysfunction and dystonia following preterm birth, we developed a new model of preterm birth in mice.

Methods: We induced preterm birth in C57BL/6J mice at embryonic day 18.3, ~24 h early. Leg adduction variability and amplitude, metrics we have shown distinguish between dystonia from spasticity during gait in people with CP, were quantified from gait videos of mice. Parvalbumin-positive interneurons, the largest population of cortical inhibitory interneurons, were quantified in the sensorimotor cortex and striatum.

Results: Mice born preterm demonstrate increased leg adduction amplitude and variability during gait, suggestive of clinically observed dystonic gait features. Mice born preterm also demonstrate fewer parvalbumin-positive interneurons and reduced parvalbumin immunoreactivity in the sensorimotor cortex, but not the striatum, suggesting dysfunction of cortical inhibition.

Conclusions: These data may suggest an association between cortical dysfunction and dystonic gait features following preterm birth. We propose that our novel mouse model of preterm birth can be used to study this association.

Impact: Mouse models of true preterm birth are valuable for studying clinical complications of prematurity. Mice born preterm demonstrate increased leg adduction amplitude and variability during gait, suggestive of clinically observed dystonic gait features. Mice born preterm demonstrate fewer parvalbumin-positive interneurons and reduced parvalbumin immunoreactivity in the sensorimotor cortex, suggesting dysfunction of cortical inhibition. Mice born preterm do not demonstrate changes in parvalbumin immunoreactivity in the striatum. Cortical dysfunction may be associated with dystonic gait features following preterm birth.