Researchers at the University of Maryland School of Medicine (UMSOM) and colleagues at Ohio State University have discovered that allergic reactions trigger changes in brain behavior development in unborn males and females. This latest brain development discovery ultimately will help researchers better understand how neurological conditions can differ between men and women.
It is the first study to assess the response of a type of immune cell called a mast cell, linked to allergic responses, to determine if these cells play a role in sexual behavior development.
“Many mental health and neurological disorders show a sex bias in prevalence; this latest research shows that inflammatory events, like allergic reactions, early in life may influence males and females differently due to underlying sex differences in the neuro immune system,” said Margaret McCarthy, PhD, professor of pharmacology and chair of the Department of Pharmacology, whose lab conducted the research that was initiated by Katherine Lenz, PhD, an assistant professor in the Department of Psychology at Ohio State University.
These findings, which were published in Scientific Reports, illustrate that immune cells are involved in the process of brain sexual differentiation and that prenatal allergic inflammation can impact this crucial process in both sexes. This finding is another discovery that ultimately will help researchers understand behavioral development differences between males and females.
How Allergic Reactions Impact Sexual Behavior
Researchers tested the sexual differentiation in rats that were exposed to an allergic reaction while still in utero. They induced an allergic reaction to egg whites in pregnant rats, and results of the study showed the allergic reaction impacted behavior changes in the offspring. Male rats showed less male sexual behavior as adults and adult females behaved more like male rates.
The research tracked mast cells, which are known for their role in allergic responses. Researchers sought to determine if exposure to an allergic response of the pregnant female in utero would alter the sexual differentiation of the offspring and result in sociosexual behavior in later life.
“This research shows that early life allergic events may contribute to natural variations in both male and female sexual behavior, potentially via underlying effects on brain-resident mast cells,” McCarthy said.
Sexual differentiation takes place in the early life process and is directed by sex chromosomes, hormones, and early life experiences. What this research showed is that immune cells residing in the brain such as microglia and mast cells are more numerous in the male than female rat brains, and these cells play a critical role in brain development.
“This research is an important discovery in the science behind brain development in males and females as we address brain disorders early in life. It builds upon the research at the University of Maryland School of Medicine that uncovers how male and female brains differ, which will ultimately help in treating a wide range of serious brain disorders,” said UMSOM Dean E. Albert Reece, MD, PhD, MBA, who also is the executive vice president for medical affairs, University of Maryland, Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor.
The research was funded by the National Institutes of Health and the Ohio State University Startup Funds to KML.