REPEATED EXPOSURE TO THE POLYCHLORINATED BIPHENYL (AROCLOR-1254) ELEVATES THE BASAL SERUM LEVELS OF CORTICOSTERONE BUT DOES NOT AFFECT THE STRESS-INDUCED RISE

Previous studies indicate that repeated exposure of weanling male Fisc her 344 rats to Aroclor can cause immune system alterations but the pa ttern of effects suggested the release of corticosteroids may have pla yed a role. Rats were exposed daily by gastric intubation to the polyc hlorinated biphenyl (PCB) Aroclor 1254 at 0.1, 1.0, 10, or 25 mg/kg fo r exposure durations of 5, 10 or 15 weeks. By the ]5th week of dosing all groups displayed an elevation in the basal level of serum corticos terone but no change in adrenal weight. Fur-ther, rats exposed to Aroc lor 1254 for 15 weeks and subjected to stress prior to serum collectio n displayed elevations in corticosterone levels equivalent to stressed control rats. The failure to observe altered adrenal structure indica tive of hyperactivity in the presence of increased serum levels of cor ticosterone suggest these basal increases may be indirect rather than direct effects of Aroclor 1254.