Maternal high-fat diet leads to persistent synaptic instability in mouse offspring via oxidative stress during lactation

• Offspring from HFD-fed dams exhibited synaptic instability and progressive spine loss.
• Offspring form HFD-fed dams and consuming HFD showed severe decline in the spines.
• The synaptic defects were caused even by HFD exposure exclusively during lactation.
• Antioxidant-treatment during lactation ameliorated the synaptic impairments.

Maternal obesity has negative effects on the neurodevelopment of the offspring. Pups from high-fat diet (HFD)-fed mice exhibit peroxidized lipid accumulations in the brain and behavioral impairments. However, the synaptic basis of maternal HFD-induced brain dysfunction in offspring remains unclear. In the present study, we focused on the dynamics and morphology of postsynaptic dendritic spines and filopodia in the offspring of HFD-fed mouse dams, using in vivo two-photon imaging, chosen because of the involvement of peripheral organs and non-neuronal cells in the abnormal metabolic state. We observed instability of dendritic spines and filopodia in the cerebral cortex of offspring from HFD-fed dams. Interestingly, the synaptic instability persisted into adulthood with a lower spine density even when the offspring were fed with a normal diet after weaning. HFD-fed offspring from HFD-fed dams showed a severe disruption of dendritic spines. Synaptic instability and loss of spines were caused even by HFD exposure exclusively during lactation. The treatment of ascorbic acid, an antioxidant, during lactation ameliorated the synaptic impairments. These results suggest that maternal obesity leads to persistent synaptic impairments in the offspring, which may be associated with behavioral deficits in adulthood, and that these synaptic deficits may be due to oxidative stress from peroxidized lipid accumulations during the lactation period.