In an article published on July 16, 2018 in the peer-reviewed Journal of Neuroscience, Daniel Kougias and colleagues from the Neuroscience Program, University of Illinois, Champaign, U.S., reported on the phthalates’ effects on the developing brain and cognitive flexibility in rats.
Female rats were orally exposed “through pregnancy and for 10 days while lactating” to a mixture of six phthalates at two concentrations comparable to the U.S. population exposure levels. The phthalate mixture contained 35% diethyl phthalate (DEP, CAS 84-66-2), 21% bis(2-ethylhexyl) phthalate (DEHP, CAS 117-81-7), 15% dibutyl phthalate (DBP, CAS 84-74-2), 15% diisononyl phthalate (DiNP, CAS 28553-12-0), 8% diisobutyl phthalate (DiBP, CAS 84-69-5), and 5% benzyl butyl phthalate (BBP, CAS 85-68-7). The offspring of the exposed rats were then tested as adults in a setup which assesses cognitive flexibility, followed by a quantification of the number of neurons, glia, and synapses in their brains, specifically in the medial prefrontal cortex (mPFC). This region is “involv[ed] in executive functions and implic[ated] in the pathology of many neuropsychiatric disorders,” including autism.
Both male and female rats perinatally exposed to phthalate mixture were found to have “a deficit in cognitive flexibility,” accompanied by “a reduction in neuron number, synapse number, and size of the mPFC.” The scientists observed that “the number of synapses was correlated with cognitive flexibility, such that rats with fewer synapses were less cognitively flexible than those with more synapses.”
The authors conclude that their results “demonstrate that perinatal phthalate exposure can have long-term effects on the cortex and behavior of both male and female rats” and “may have serious implication for humans.”
EurekAlert (July 16, 2018). “Plastic chemical linked to smaller prefrontal cortex, reduced cognitive ability in rats.”
Kougias, D., et al. (2018). “Perinatal exposure to an environmentally relevant mixture of phthalates results in a lower number of neurons and synapses in the medial prefrontal cortex and decreased cognitive flexibility in adult male and female rats.” Journal of Neuroscience (published July 16, 2018)