Astrocyte-mediated hepatocyte growth factor/scatter factor supplementation restores GABAergic interneurons and corrects reversal learning deficits in mice.

Many psychiatric and neurological disorders present persistent neuroanatomical abnormalities in multiple brain regions that may reflect a common origin for a developmental disturbance. In mammals, many of the local GABAergic inhibitory interneurons arise from a single subcortical source. Perturbations in the ontogeny of the GABAergic interneurons may be reflected in the adult by interneuron deficits in both frontal cerebral cortical and striatal regions. Disrupted GABAergic circuitry has been reported in patients with schizophrenia and frontal lobe epilepsy and may contribute to their associated impairments in behavioral flexibility. The present study demonstrates that one type of behavioral flexibility, reversal learning, is dependent upon proper numbers of GABAergic interneurons. Mice with abnormal interneuron ontogeny have reduced numbers of parvalbumin-expressing GABAergic local interneurons in the orbitofrontal cortical and striatal regions and impaired reversal leaning. Using a genetic approach, both the anatomical and functional deficiencies are restored with exogenous postnatal growth factor supplementation. These results show that GABAergic local circuitry is critical for modulating behavioral flexibility and that birth defects can be corrected by replenishing crucial growth factors.