Allergies during pregnancy contribute to changes in the brains of rat offspring

November 16, 2016 by Misti Crane, The Ohio State University

A new study in rats could begin to explain why allergies during pregnancy are linked to higher risks for attention-deficit hyperactivity disorder and autism in children.

Researchers at The Ohio State University found significant changes in the brain makeup of fetuses and newborn rats exposed to allergens during pregnancy.

Animals that lived to adulthood after allergen exposure before birth showed signs of hyperactivity and antisocial behavior and decreased anxiety, found a research team led by Kathryn Lenz, an Ohio State assistant professor of psychology.

"This is evidence that prenatal exposure to allergens alters brain development and function and that could be an underappreciated factor in the development of neurodevelopmental disorders," said Lenz, who presented her research Nov. 16 in San Diego at Neuroscience 2016, the annual meeting of the Society for Neuroscience.

Though there are established links between allergies and ADHD and autism - as well as between inflammation and risk of autism, schizophrenia and ADHD - the cellular-level changes that could contribute to those connections largely remain a mystery.

Autism and ADHD are both three to four times as common in boys than in girls, Lenz said. And so she and her collaborators set out to look for sex differences in the rats as well.

"We're really interested in figuring out unknown factors in psychological disorders and in differences between male and female brain development as it relates to autism, ADHD and other disorders," Lenz said.

To study the effects of allergies on offspring, researchers sensitized female rats to ovalbumin (found in egg whites) before pregnancy. Then, 15 days into their pregnancies, they exposed them to the allergen, prompting an immune response in the animals.

They analyzed whether prenatal allergen exposure changed the number and behavior of immune cells in the developing brain of offspring. They explored possible changes in young rats' physical activity, anxiety-like behavior, ability to learn and sociability. And they examined the density of dendritic spines in the juvenile animals' brains. The spines protrude from neurons and are vital to cellular-level communication in the brain.

Rats exposed to allergens before birth had higher levels of immune cells called mast cells in the brain and lower numbers of called microglia, regardless of the animals' gender.

Animals with allergic mothers were hyperactive, but had lower levels of anxiety-like behavior. When they interacted with other juvenile rats, the males in the allergen group were less likely to roughhouse with their peers.

"Young rats engage in social play and males are more rough and tumble and usually play much more than females," Lenz said.

"The males born to the allergen-exposed mothers looked more like females. They were more socially reserved. They were really hyperactive, but socially disengaged. That looks a bit like ADHD."

And when the researchers looked at the animals' ability to be mentally flexible, the rats born to allergic mothers had a tougher time, Lenz said.

"They have to use rules to find a reward - a Cheerio in a terracotta pot - and the rules we give them keep shifting," Lenz said, explaining that in one test the treat might be in a pot covered in sandpaper and in another test it might be in a pot covered in velvet.

The in the allergen group weren't as capable of adapting to the changing parameters of the test, and the males had deficits that were more significant than the females.

Early data from the study shows that the - the points of synaptic connection between cells in the frontal cortex of the animals' brains - were decreased in males with allergy exposure and increased in their female counterparts.

Explore further: Seasonal allergies could change your brain

Related Stories

Seasonal allergies could change your brain

August 8, 2016
Hay fever may do more than give you a stuffy nose and itchy eyes, seasonal allergies may change the brain, says a study published in the open-access journal Frontiers in Cellular Neuroscience.

Chronic stress during pregnancy prevents brain benefits of motherhood, study shows

October 14, 2012
A new study in animals shows that chronic stress during pregnancy prevents brain benefits of motherhood, a finding that researchers suggest could increase understanding of postpartum depression.

Exposure to endocrine disruptors during pregnancy affects the brain two generations later

March 5, 2015
Prenatal exposure to low doses of the environmental contaminants polychlorinated biphenyls, or PCBs, change the developing brain in an area involved in metabolism, and some effects are apparent even two generations later, ...

Stress relief by 'comfort foods' may vary between sexes and across the estrous cycle

July 12, 2016
Researchers at the University of Cincinnati have found that the brain networks that mediate stress relief after eating highly palatable foods may vary between males and females, and may also depend on the stage of the estrous ...

Study finds link between exposure to synthetic progestin during development, impaired cognitive function

March 9, 2016
Exposure to synthetic progestin – a steroid hormone used to prevent premature birth in at risk women – has been linked to impaired cognitive function in a recent animal study co-authored by University at Albany Psychologist ...

Research shows why antidepressant may be effective in postpartum depression

November 19, 2014
An antidepressant commonly prescribed for women with postpartum depression may restore connections between cells in brain regions that are negatively affected by chronic stress during pregnancy, new research suggests.

Recommended for you

New technique helps uncover changes in ALS neurons

June 22, 2018
Northwestern Medicine scientists have discovered that some neurons affected by amyotrophic lateral sclerosis (ALS) display hypo-excitability, using a new method to measure electrical activity in cells, according to a study ...

Broken shuttle may interfere with learning in major brain disorders

June 22, 2018
Unable to carry signals based on sights and sounds to the genes that record memories, a broken shuttle protein may hinder learning in patients with intellectual disability, schizophrenia, and autism.

Watching stem cells repair spinal cord in real time

June 22, 2018
Monash University researchers have restored movement and regenerated nerves using stem cells in zebra fish where the spinal cord is severely damaged.

Scientists discover fundamental rule of brain plasticity

June 21, 2018
Our brains are famously flexible, or "plastic," because neurons can do new things by forging new or stronger connections with other neurons. But if some connections strengthen, neuroscientists have reasoned, neurons must ...

Waking up is hard to do: Prefrontal cortex implicated in consciousness

June 21, 2018
Philosophers have pondered the nature of consciousness for thousands of years. In the 21st century, the debate over how the brain gives rise to our everyday experience continues to puzzle scientists. To help, researchers ...

Researchers find mechanism behind choosing alcohol over healthy rewards

June 21, 2018
A new study links molecular changes in the brain to behaviours that are central in addiction, such as choosing a drug over alternative rewards. The researchers have developed a method in which rats learn to get an alcohol ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.