Adrenocorticotrophin- and cyclic adenosine 3 prime , 5 prime -monophosphate-stimulated cortisol secretion in interrenal tissue of rainbow trout exposed in vitro to DDT compounds

The effects of DDT compounds on the function and viability of interrenal corticosteroidogenic tissue were investigated in vitro in rainbow trout (Oncorhynchus mykiss) in a dose-response study. The o,p prime -dichlorodiphenyldichloroethane (DDD) was the most potent of the tested chemicals in decreasing adrenocorticotropic hormone (ACTH)-stimulated cortisol secretion by head kidney fragments compared with controls. The dbcAMP-stimulated cortisol secretion was also impaired with doses of 50 and 100 mg/L o,p prime -DDD but not 25 mg/L. Tissue viability, estimated by the release of lactate dehydrogenase (LDH), was similar to controls at 25 mg/L and was decreased significantly at 50 and 100 mg/L o,p prime -DDD. These results suggest that o,p prime -DDD is an adrenotoxic compound that may disrupt the 3 prime ,5 prime -monophosphate (cAMP) generation step and, at higher doses, induce irreversible cytotoxic effects. The p,p prime -DDT induced a significant inhibition in the secretory response to ACTH and dbcAMP only at 100 mg/L, while p,p prime -DDD had no effect on the cortisol secretion. A significantly decreased viability was detected at the higher doses of p,p prime -DDT and p,p prime -DDD without a detectable disruption of cortisol synthesis. The steroidogenic interrenal cells may be less sensitive to the DDT compounds tested than other cell populations within the teleost head kidney.