A new study shows that activating a mother's immune system during her pregnancy significantly disrupts brain cell development in her offspring.


Researchers with the UC Davis Center for Neuroscience and Department of Neurology said their findings show how maternal viral infections may increase the risk of having a child with autism spectrum disorder (ASD) or schizophrenia.


According to them, this is the first evidence that neurons in the developing brain of newborn offspring are altered by maternal immune activation.


This study was conducted in mice and rats. It compared the brains of the offspring of rodents whose immune systems had been activated to those whose animals whose immune systems had not been activated.


Study authors found that pups born to animals exposed to viral infection had higher brain levels of immune molecules known as the major Histocompatibility complex I (MHCI) molecules - suggesting that brain cells in offspring are altered by maternal immune activation.


These high MHCI levels prevented brain cells in newborn mice from forming synapses, which are the tiny gaps separating brain cells through which signals are transmitted. While the human brain has about 100 billion brain cells or neurons, it has around 100 trillion synapses!


When the researchers reduced MHCI to normal levels in these brain cells, synapses returned to being formed as usual. In other words, maternal immune activation does change how connections form between brain cells in their offspring.


So this is a significant finding because earlier research suggests that ASD and schizophrenia may be caused by changes in how connections are formed in the brain, especially in the brain area known as the cerebral cortex.


This finding provides a potential mechanism linking maternal immune activation to disease-linked behaviors.


In the future, a better understanding of how this mechanism works may help scientists to develop diagnostic tests, and eventually therapies, to improve the lives of individuals with ASD, schizophrenia and similar disorders.


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