Prenatal Activation of Microglia Induces Delayed Impairment of Glutamatergic Synaptic Function

BACKGROUND: Epidemiological studies have linked maternal infection during pregnancy to later development of neuropsychiatric disorders in the offspring. In mice, experimental inflammation during embryonic development impairs behavioral and cognitive performances in adulthood. Synaptic dysfunctions may be at the origin of cognitive impairments, however the link between prenatal inflammation and synaptic defects remains to be established. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we show that prenatal alteration of microglial function, including inflammation, induces delayed synaptic dysfunction in the adult. DAP12 is a microglial signaling protein expressed around birth, mutations of which in the human induces the Nasu-Hakola disease, characterized by early dementia. We presently report that synaptic excitatory currents in mice bearing a loss-of-function mutation in the DAP12 gene (DAP12(KI) mice) display enhanced relative contribution of AMPA. Furthermore, neurons from DAP12(KI) P0 pups cultured without microglia develop similar synaptic alterations, suggesting that a prenatal dysfunction of microglia may impact synaptic function in the adult. As we observed that DAP12(KI) microglia overexpress genes for IL1beta, IL6 and NOS2, which are inflammatory proteins, we analyzed the impact of a pharmacologically-induced prenatal inflammation on synaptic function. Maternal injection of lipopolysaccharides induced activation of microglia at birth and alteration of glutamatergic synapses in the adult offspring. Finally, neurons cultured from neonates born to inflamed mothers and cultured without microglia also displayed altered neuronal activity. CONCLUSION/SIGNIFICANCE: Our results demonstrate that prenatal inflammation is sufficient to induce synaptic alterations with delay. We propose that these alterations triggered by prenatal activation of microglia provide a cellular basis for the neuropsychiatric defects induced by prenatal inflammation

Neonatal regulatory behavior problems are predicted by maternal early pregnancy overweight and obesity:findings from the prospective PREDO Study

Abstract Introduction: Maternal overweight/obesity and comorbid hypertensive disorders and gestational diabetes associate with neurodevelopmental delay in the offspring in childhood. We hypothesize that these maternal conditions associate also with the offspring regulatory behavior problems and impact on neurodevelopment via the offspring regulatory behavior. Methods: A number of 3117 women of the PREDO Study filled in a questionnaire on regulatory behavior problems at the child’s mean age of 16.9 days and 2116 of them a questionnaire on developmental milestones at the child’s mean age of 42.2 months. Data on maternal BMI and comorbid disorders come from the Finnish Medical Birth Register. Results: Offspring of overweight/obese mothers in comparison to normal weight mothers had higher levels of regulatory behavior problems and 22% (95% confidence interval 5–42%) higher odds of having problems on multiple domains of behavioral regulation at the mean age of 16.9 days. Offspring regulatory behavior problems partially mediated the association between maternal overweight/obesity and developmental milestones comprising communication, gross motor, fine motor, problem solving, and personal/social domains of development. Comorbid disorders did not associate with offspring regulatory behavior problems. Conclusion: Regulatory behavior problems of the offspring have prenatal origins and partially mediate the effects of maternal overweight/obesity on offspring neurodevelopment