Short-term effects of a perinatal exposure to a 16 polycyclic aromatic hydrocarbon mixture in rats: assessment of early motor and sensorial development and cerebral cytochrome oxidase activity in pups.

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs), a family of ubiquitous neurotoxic pollutants, mainly through ingestion of contaminated food. Developing organisms can be exposed also to PAHs due to the ability of these compounds to pass through the placental barrier as well as through the breast milk. Previous animal studies have reported that the exposure of rats to a 16 PAH mixture at environmental doses strictly limited to gestation did not induce any long-lasting consequences, whereas gestational and lactational PAH exposure induced long-term behavioral and cerebral metabolic effects. In the present study, short-term effects of exposures to the same PAH mixture during gestation, or during gestation and lactation, were assessed by evaluating motor and sensory development of rat pups, and by measuring cerebral cytochrome oxidase activity (a marker of energetic metabolism) in different brain areas. Brain levels of PAHs and some monohydroxylated metabolites were also evaluated in pups at birth and at 21 days of postnatal life. No significant short-term modifications of behavioral development and of cerebral metabolism were observed following an early PAH exposure whatever the dose and the period of exposure. Surprisingly, the same brain levels of concentration of PAHs and metabolites were observed in control and exposed pups in both studies. These analytical results raise the difficulty in overcoming environmental contamination of control animals and the choice of such controls in experimental studies which focus on neurotoxicity of exposure to low levels of pollutants.