INTRODUCTION: Maternal separation, as a serious early-life stressor (ELS), has been recognized as a high risk factor that can lead to many psychiatric disorders. Disruptions in the medial prefrontal cortex (mPFC) are strictly related to those disorders. However, little is known about exact effects of ELS on neuronal function in mPFC. GABAergic interneurons are inhibitory neurons that are involved in basic brain functions and maintaining excitation/inhibition balance (E/I balance) in the neuronal networks. Somatostatin-expressing (SST) interneurons are a subtype of GABAergic neurons, which control the output of cortical pyramidal neurons.

AIM(S): The aim of the study was to dissect the effects of maternal separation on electrophysiological properties of SST interneurons in the mouse mPFC.

METHOD(S): Transgenic mice with fluorescently labeled SST interneurons were subjected to maternal separation between the 1st and the 20th postnatal day, for 3 hours daily. Mice from control groups were left undisturbed with their dams until weaning. Over the next few days behavioral tests were performed on both groups. After behavioral testing, whole-cell patch-clamp recordings were performed in acute brain slices. To measure E/I balance, miniature excitatory and inhibitory postsynaptic currents (mEPSC/mIPSC) were recorded in SST interneurons.

RESULTS: Statistical analysis revealed changes in mEPSCs but not in mIPSCs in SST interneurons after maternal separation; the amplitude of mEPSCs was significantly lower than in the control group, whereas the mEPSC frequency did not change between the groups.

CONCLUSIONS: These results suggest that ELS related to maternal separation weakens excitatory transmission to SST interneurons. This study provides an insight into the effects of the early-life maternal separation on the function of SST interneurons in the mPFC of offspring.

FINANCIAL SUPPORT: This study was supported by National Science Centre Poland, OPUS grant no. 2025/57/B/NZ5/03816 to JUC, OPUS grant no. 2020/39/B/NZ4/01462 to JUC.