Neonatal maternal separation impairs cognitive function and synaptic plasticity in adult male CD-1 mice

Maternal separation (MS) increases the risk of occurrence of anxiety, depression, and learning and memory impairment in offspring. However, the underlying molecular biological mechanisms remain unclear. In the current study, offspring CD-1 mice were separated from their mothers from postnatal day 4 to postnatal day 21. At 3 months of age, the male offspring were selected for the evaluation of anxiety- and depression-like behaviors and learning and memory function. Western blotting and RT-PCR were used to examine the expression levels of brain-derived neurotrophic factor, tyrosine kinase receptor B, postsynaptic density-95, and synaptophysin. Long-term potentiation (LTP) and long-term depression (LTD) were recorded at Schaffer collateral/CA1 synapses. Furthermore, basal synaptic transmission was evaluated via the recording of the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs). The results showed that adult offspring CD-1 mice displayed anxiety- and depressive-like behaviors as well as impaired spatial learning and memory abilities. Electrophysiological analysis indicated that MS impaired LTP, enhanced LTD, and reduced the frequency of mEPSCs in pyramidal neurons in the CA1 region. Our findings suggested that MS can lead to anxiety, depression, and cognitive deficits, and these effects are associated with alterations in the levels of synaptic plasticity-associated proteins, consequently, also synaptic plasticity.