Behavioral effects following single and combined maternal exposure to PCB 77 (3,4,3 ',4 '-tetrachlorobiphenyl) and PCB 47 (2,4,2 ',4 '-tetrachlorobiphenyl) in rats

The present study has compared the neurobehavioral effects of two structura lly different PCB congeners or their combination in rats. Time-mated Long-E vans rats received daily injections of the coplanar PCB 77 (3,4 3',4'-TCB: 0.5 or 1.5 mg/kg), the di-ortho-chlorinated PCB 47 (2,4,2',4'-TCB: 1.5 mg/k g) or a congener mixture (0.5 mg/kg PCB 77 + 1.0 mg/kg PCB 47) from day 7 t o 18 of gestation. The PCB exposure levels in brain acid perirenal fat of d ams and offspring were determined by GC/ECD on gestational day 19 (GD 19), postnatal day 21 (PND 21), and PND 45. PCB 77 was accumulated to a smaller degree than PCB 47. On GD 19, PCB 77 was found to a greater extent in the b rains of the offspring than in the brains of the darns, whereas the level o f PCB 47 was almost the same in dams and offspring. The testing of open-fie ld behavior in male rats on PND 18 and PND 70 revealed an altered distribut ion of activity with enhanced activity in the inner zone in PCB 77-treated rats compared to all other groups, while the overall activity was not chang ed. Distance traveled and rearing behavior on PND 340 were elevated relativ e to controls in all PCB-treated groups, indicating age-related effects of maternal exposure. A step-down passive avoidance task revealed decreased la tencies in the PCB 77 and combined exposure groups on PND 80. Only PCB 77-t reated animals showed increased latencies on PND 100 on the haloperidol-ind uced catalepsy test. These results indicate long-term effects of maternal e xposure to PCB 77 on emotional and motor functions. At the dose levels used in the present experiments, the two congeners given in combination did not cause additive or synergistic effects. Instead, concurrent exposure to PCB 47 seemed to counteract PCB 77-induced changes in the pattern of activity. (C) 1999 Elsevier Science Inc. All rights reserved.