Postnatal maternal separation enhances tonic GABA current of cortical layer 5 pyramidal neurons in juvenile rats and promotes genesis of GABAergic neurons in neocortical molecular layer and subventricular zone in adult rats

• Postnatal maternal separation (PMS) changed explorative activity and anxiety in rats.
• PMS increased the cell proliferation in the adult brain and promoted the new generated cells to differentiate into GABAergic neurons.
• PMS adult brain maintained higher ratios of GABAergic neurons in the survival of newly generated cells within PMS.
• PMS increased the tonic GABA currents in cortical layer 5 pyramidal cells.
• GABAergic transmission in neurons may play key roles in the development of certain psychiatric disorders after PMS.

Postnatal maternal separation (PMS) has been shown to be associated with an increased vulnerability to psychiatric illnesses in adulthood. However, the underlying neurological mechanisms are not well understood. Here we evaluated its effects on neurogenesis and tonic GABA currents of cortical layer 5 (L5) pyramidal neurons. PMS not only increased cell proliferation in the subventricular zone, cortical layer 1 and hippocampal dentate gyrus in the adult brain, but also promoted the newly generated cells to differentiate into GABAergic neurons, and PMS adult brain maintained higher ratios of GABAergic neurons in the survival of newly generated cells within 5 days immediately post PMS. Additionally, PMS increased the tonic currents at P7–10 and P30–35 in cortical L5 pyramidal cells. Our results suggest that the newly generated GABAergic neurons and the low GABA concentration-activated tonic currents may be involved in the development of psychiatric disorders after PMS.