Effects of 2,2',4,4',5,5'-hexachlorobiphenyl on testosterone production in vitro

Mouse Leydig cells were incubated with 2,2',4,4',5,5'-hexachlorobiphenyl (6-CB, 2.9 or 14.3 mug/ml). Testosterone production increased during the first 3-4 hr of incubation without addition of gonadotropin. The substance also affected cell viability in that the concentration of Leydig cells began to decrease soon after the start of the incubation and the percentage of dead cells increased throughout the incubation period. A technical mixture of polychlorinated biphenyls (Clophen A50(R)) was used as a control to test the relationship between cell death and testosterone production. This preparation, which was slightly more toxic to the cells than was 6-CB, did not stimulate basal testosterone production. No binding of (14)C-labelled 6-CB to the Leydig-cell gonadotropin receptors could be demonstrated.