Behavioral effects of PCB exposure in an animal model of Attention-Deficit / Hyperactivity Disorder : the spontaneously hypertensive rat

Abstract

Background: Polychlorinated biphenyls are a class of organic compounds that bioaccumulate due to their hydrophobic and lipophilic properties. The main source of exposure for humans is through food consumption as adolescents or adults and through breast milk as infants. Exposure might have a variety of adverse effects, like impairment of cognitive function as well as effects on neurological development, depending on the organisms´ age at exposure. Effects of PCBs are associated with the same impairments in neurobehavioral function as in ADHD. Methods: A total of 212 rats were tested in this study. 104 Spontaneously Hypertensive rats (SHR) and 108 Wistar Kyoto rats (WKY) were orally given three different doses of PCB 153; 1mg/kg, 3mg/kg or 6mg/kg, between postnatal day 8 and 21. Control groups were given pure corn oil. The animals were tested on a variable interval reinforcement schedule measuring activity level, impulsivity and sustained attention. Results: Rats exposed to PCB 153 showed changes in activity, impulsivity and sustained attention. This was true for SHR, but not WKY. There was an effect of dose in exposed animals. The SHR given 1mg/kg of PCB were different on behavioral outcome in comparison with animals given 3mg/kg of PCB, 6mg/kg of PCB or corn oil. Both male and female SHR showed behavioral effects following PCB exposure. Conclusion: The two strains of rats responded differently to the doses of PCB 153. There was an increased sensitivity to PCB exposure in the animal model of ADHD, SHR, both males and females, but not in WKY.