Exposure to High Doses of the di-ortho-Substituted Polychlorinated Biphenyls 153 and 180, But Not 52, Leads to Behavioural Changes in Rats

Background: Polychlorinated Biphenyls (PCBs) are a group of toxins that are hydrophobic and lipophilic. Acute and chronical exposure through mother’s milk and food consumption can produce hyperactivity and disturbances in cognitive development in humans. Animal studies have shown inconsistent changes in behaviour and attention. More consistent findings of reductions in dopamine levels have also been found. This makes PCB exposure relevant for certain dopamine based diseases, such as Parkinson’s disease (PD) and Attention Deficit/Hyperactive Disorder (ADHD). Methods: Male outbreed Wistar Kyoto (WKY/NHsd) rats were exposed to 10 mg/kg PCBs 52, 153 or 180 dissolved in corn oil by gavage three times between PND 10 and 20. A control group were given pure corn oil. At postnatal day (PND) 35 the rats started testing on a RI EXT reinforcement schedule measuring activity, impulsivity and sustained attention. Results: Rats exposed to PCB 153 or 180 showed significantly less activity and impulsive behaviour than the controls and PCB 52 group. The PCB 153 and 180 groups also performed better on the sustained attention measure. No such results were found for the PCB 52 group. Discussion: It is suggested that the high dose of exposure to the highly chlorinated congeners PCB 153 and PCB 180 produced motor problems in the rats causing hypoactivity. The effect thus more resembles PD symptoms than ADHD. Further research is recommended on dose-response curves and animal models of the disorders investigating a possible genetic vulnerability factor

Postnatal exposure to PCB 153 and PCB 180, but not to PCB 52, produces changes in activity level and stimulus control in outbred male Wistar Kyoto rats

Abstract Background Polychlorinated biphenyls (PCBs) are a class of organic compounds that bioaccumulate due to their chemical stability and lipophilic properties. Humans are prenatally exposed via trans-placental transfer, through breast milk as infants, and through fish, seafood and fatty foods as adolescents and adults. Exposure has several reported effects ranging from developmental abnormalities to cognitive and motor deficiencies. In the present study, three experimental groups of rats were orally exposed to PCBs typically found in human breast milk and then behaviorally tested for changes in measures of stimulus control (percentage lever-presses on the reinforcer-producing lever), activity level (responses with IRTs > 0.67 s), and responses with short IRTs ( Methods Male offspring from Wistar Kyoto (WKY/NTac) dams purchased pregnant from Taconic Farms (Germantown, NY) were orally given PCB at around postnatal day 8, 14, and 20 at a dose of 10 mg/kg body weight at each exposure. Three experimental groups were exposed either to PCB 52, PCB 153, or PCB 180. A fourth group fed corn oil only served as controls. From postnatal day 25, for 33 days, the animals were tested for behavioral changes using an operant procedure. Results PCB exposure did not produce behavioral changes during training when responding was frequently reinforced using a variable interval 3 s schedule. When correct responses were reinforced on a variable interval 180 s schedule, animals exposed to PCB 153 or PCB 180 were less active than controls and animals exposed to PCB 52. Stimulus control was better in animals exposed to PCB 180 than in controls and in the PCB 52 group. Also, the PCB 153 and PCB 180 groups had fewer responses with short IRTs than the PCB 52 group. No effects of exposure to PCB 52 were found when compared to controls. Conclusions Exposure to PCBs 153 and 180 produced hypoactivity that continued at least five weeks after the last exposure. No effects of exposure to PCB 52 were observed.</p

Postnatal exposure to PCB 153 and PCB 180, but not to PCB 52, produces changes in measures of attention, activity level and impulsivity in outbred male Wistar Kyoto rats

Background: Polychlorinated biphenyls (PCBs) are a class of organic compounds that bioaccumulate due to their chemical stability and lipophilic properties. Humans are prenatally exposed via trans-placental transfer, through breast milk as infants, and through fish, seafood and fatty foods as adolescents and adults. Exposure has several reported effects ranging from developmental abnormalities to cognitive and motor deficiencies. In the present study, three experimental groups of rats were orally exposed to PCBs typically found in human breast milk and then behaviorally tested for changes in measures of stimulus control (percentage lever-presses on the reinforcer- producing lever), activity level (responses with IRTs > 0.67 s), and responses with short IRTs (< 0.67 s). Methods: Male offspring from Wistar Kyoto (WKY/NTac) dams purchased pregnant from Taconic Farms (Germantown, NY) were orally given PCB at around postnatal day 8, 14, and 20 at a dose of 10 mg/kg body weight at each exposure. Three experimental groups were exposed either to PCB 52, PCB 153, or PCB 180. A fourth group fed corn oil only served as controls. From postnatal day 25, for 33 days, the animals were tested for behavioral changes using an operant procedure. Results: PCB exposure did not produce behavioral changes during training when responding was frequently reinforced using a variable interval 3 s schedule. When correct responses were reinforced on a variable interval 180 s schedule, animals exposed to PCB 153 or PCB 180 were less active than controls and animals exposed to PCB 52. Stimulus control was better in animals exposed to PCB 180 than in controls and in the PCB 52 group. Also, the PCB 153 and PCB 180 groups had fewer responses with short IRTs than the PCB 52 group. No effects of exposure to PCB 52 were found when compared to controls. Conclusions: Exposure to PCBs 153 and 180 produced hypoactivity that continued at least five weeks after the last exposure. No effects of exposure to PCB 52 were observed

Postnatal exposure to PCB 153 and PCB 180, but not to PCB 52, produces changes in measures of attention, activity level and impulsivity in outbred male Wistar Kyoto rats

Background: Polychlorinated biphenyls (PCBs) are a class of organic compounds that bioaccumulate due to their chemical stability and lipophilic properties. Humans are prenatally exposed via trans-placental transfer, through breast milk as infants, and through fish, seafood and fatty foods as adolescents and adults. Exposure has several reported effects ranging from developmental abnormalities to cognitive and motor deficiencies. In the present study, three experimental groups of rats were orally exposed to PCBs typically found in human breast milk and then behaviorally tested for changes in measures of stimulus control (percentage lever-presses on the reinforcer-producing lever), activity level (responses with IRTs > 0.67 s), and responses with short IRTs (< 0.67 s). Methods: Male offspring from Wistar Kyoto (WKY/NTac) dams purchased pregnant from Taconic Farms (Germantown, NY) were orally given PCB at around postnatal day 8, 14, and 20 at a dose of 10 mg/kg body weight at each exposure. Three experimental groups were exposed either to PCB 52, PCB 153, or PCB 180. A fourth group fed corn oil only served as controls. From postnatal day 25, for 33 days, the animals were tested for behavioral changes using an operant procedure. Results: PCB exposure did not produce behavioral changes during training when responding was frequently reinforced using a variable interval 3 s schedule. When correct responses were reinforced on a variable interval 180 s schedule, animals exposed to PCB 153 or PCB 180 were less active than controls and animals exposed to PCB 52. Stimulus control was better in animals exposed to PCB 180 than in controls and in the PCB 52 group. Also, the PCB 153 and PCB 180 groups had fewer responses with short IRTs than the PCB 52 group. No effects of exposure to PCB 52 were found when compared to controls. Conclusions: Exposure to PCBs 153 and 180 produced hypoactivity that continued at least five weeks after the last exposure. No effects of exposure to PCB 52 were observed