Exclusive prenatal exposure to a 16 PAH mixture does not impact anxiety-related behaviours and regional brain metabolism in adult male rats: a role for the period of exposure in the modulation of PAH neurotoxicity.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants originating from incomplete combustion processes. Humans are mainly exposed through contaminated food ingestion. PAHs are neurotoxic compounds both for human and rodents, and may be found in placenta, umbilical cord blood and breast milk, suggesting that early exposure may impact developing central nervous system. In a previous study we showed that PAH exposure during both gestation and lactation periods in rats increased anxiety-related behaviours and decreased cerebral metabolism in several key structures linked to the limbic system on male pups at the adult stage. The aim of the present study was to assess the effects of an exclusive gestational PAH exposure on the same aspects of brain functionality. Female rats were exposed through diet to a 16 PAH mixture at doses of 2 μg/kg/day or 200 μg/kg/day during gestation. Late neurotoxic effects were evaluated by carrying out behavioural and cognitive tests and histochemical analyses using cytochrome oxidase activity as a cerebral metabolism marker in different brain areas. The results of this study revealed that behaviour and cerebral metabolism on prenatally PAH exposed adult rats was not significantly affected by the exposure to these pollutants. Finally this work highlights that the exposure period to pollutants such as PAHs at very early stages of development play a key role on the neurological impairment induced.