A widely used plastic chemical appears to alter the developing brain in ways that persist into adulthood, new research suggests. Male rats exposed to the substance during pregnancy and early infancy showed heightened anxiety as grown animals, even years after contact with the chemical had ended.
The findings come from research presented at the Endocrine Society's annual meeting and point to a potential human health concern. While the work was conducted in rodents, the results suggest that humans exposed to the same chemical during vulnerable developmental windows could face similar behavioral changes.
The chemical is di-(2-ethylhexyl) phthalate, or DEHP, a plasticizer added to countless consumer products to increase flexibility. It shows up in medical devices, children's toys, shower curtains, and raincoats. Scientists have known for years that DEHP and its breakdown compounds can damage reproductive and nervous system development, but this study zeroes in on anxiety specifically.
Researchers at the University of Buenos Aires School of Medicine exposed pregnant rats to daily doses of DEHP from conception through weaning. When the male offspring reached adulthood, the team tested their anxiety levels using a standard behavioral maze. The setup exploits rodents' natural fear of heights and open spaces: rats navigate a cross-shaped platform with two open arms and two enclosed ones.
The DEHP-exposed rats avoided the open arms, spending more time in the enclosed sections and freezing in place more often than control animals. The behavioral changes suggested genuine anxiety, not mere preference for enclosed spaces.
What caught researchers' attention was whether they could reverse the effect. They tested two potential interventions: GABA agonists, which enhance the activity of an inhibitory neurotransmitter in the brain, and testosterone treatment.
Both approaches worked. Rats that received either GABA agonists or testosterone showed normal anxiety levels despite their early DEHP exposure. They explored the open arms more freely and exhibited less freezing behavior.
The findings suggest that early DEHP exposure alters brain chemistry in specific ways that can be pharmacologically corrected. Osvaldo Juan Ponzo, who led the research, noted that the behavioral changes persisted even though the rats received no additional DEHP exposure in adulthood, highlighting the permanence of developmental damage.
The research raises questions about human exposure. DEHP is ubiquitous in modern products, and children encounter it throughout their formative years. While animal models do not always translate directly to human biology, the consistency of the findings and the biological plausibility of the mechanism suggest caution is warranted.
Author Jessica Williams: "The fact that two different biological interventions can reverse anxiety caused by early DEHP exposure is intriguing, but it shouldn't distract from the real issue: why are we building anxiety into developing brains in the first place?"
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