Neurobehavioral and neurochemical effects of ortho-substituted polychlorinated biphenyl congeners in perinatally exposed rats

Polychlorinated biphenyls (PCBs) are persistent contaminants in the environment. PCBs are lipophilic and from the environment bioaccumulate in living organisms. People are exposed to PCBs through the food chain. PCB exposure during development of the central nervous system (CNS) results in behavioral dysfunction and impaired learning and memory. There are two major classes of PCBs, coplanar and ortho-substituted (OS) congeners. Most of the PCBs in environmental mixtures are the OS congeners. In vivo and in vitro studies suggest that the neurotoxic effects of PCBs might be due to exposure of the CNS to OS congeners, but there is little information on the neurobehavioral effects of these congeners.No PCB studies have yet assessed neurochemical alterations and neurobehavioral changes in the same animals. This study was undertaken to investigate the effects of combined in utero and lactational exposure to OS congeners on locomotor activity (LA), rearing, spatial learning and memory, and brain regional catecholamines. Time-mated rats were dosed with PCB 28 (2,4,4$\sp\prime$-trichlorobiphenyl; 8 or 32 mg/kg/day), PCB 118 (2,3$\sp\prime$, 4,4$\sp\prime$,5-pentachlorobiphenyl; 4 or 16 mg/kg/day), PCB 153 (2,2$\sp\prime$, 4,4$\sp\prime$,5,5$\sp\prime$-hexachlorobiphenyl; 16 or 64 mg/kg/day) or corn oil vehicle on gestation days 10-16. At weaning, a male and a female were sacrificed for neurochemical assessments (NA). Another male and female were tested on a series of behavioral tests and and sacrificed at 240 days of age for NA.PCB 28 and PCB 153 increased LA, but PCB 118 had not any effects on LA. No treatment effects were observed on an eight-arm maze. On a T-maze delayed spatial alternation task, all three congeners resulted in slower acquisition of the task by female rats. In pups, there was a sex effect on norepinephrine (NE) content in caudate putamen (CP) without any treatment effects. A similar sex difference in epinephrine (EP) content in CP was observed. No treatment effects were seen in nucleus accumbens (AC), substantia nigra (SN) or prefrontal cortex (FC). In adult rats, there was a significant decrease in NE content in SN of the males in all exposed groups. No significant neurochemical effects of PCBs were seen in FC, AC, or CP in male or female adult rats.U of I OnlyETDs are only available to UIUC Users without author permissio