Clinical epidemiological studies have implicated central nervous system problems (especially related to memory, learning) associated with exposure to polychlorinated biphenyls (PCBs), a contaminant found in the environment and especially in fish from polluted waters. benzo[a]pyrene (BaP) is another AHR ligand. The attached report suggests that this perturbation of memory and learning might extend to BaP, extensively studied as a prototypic AHR ligand and major component of combustion processes including cigarette smoke, coal burning, and charbroiled foods.
To characterize behavioral deficits in pre-adolescent offspring exposed in utero to BaP, authors treated pregnant rats with varying doses of BaP at several times during gestation. BaP metabolites were identified in plasma and whole brain or cerebral cortex from exposed and control offspring within the first few weeks after birth. Spatial
discrimination-reversal learning was used to evaluate potential behavioral neurotoxicity in offspring ages 40-60 days following birth. A dose-dependent effect of in utero BaP
was found, which was correlated with activity-related cytoskeletal-associated protein (ARC). ARC is an experience-dependent cortical protein marker known to be up-regulated in response to acquisition of a novel behavior, and ARC expression was greater in BaP-exposed offspring.
These findings support the hypothesis that in utero exposure to BaP––during critical windows of development that represent peak periods of neurogenesis––might result in behavioral deficits later in life. Whether the doses of BaP used in these rats can be extrapolated to environmental exposures such as cigarette smoking during human pregnancy, remains to be determined. Tox_Sci_In_Utero_BaP_Behavioral_Effects_2o16