Meeting Abstract
Persistent organic pollutants, such as dichlorodiphenyltrichloroethane (DDT), can remain in the environment at sub-lethal levels for decades. Analysis of soil from a DDT abatement site (Redstone Arsenal, a military installation, potentially impacting the watershed supplying Huntsville, AL) in 2017 documented levels that were still significantly above the Total Threshold Limit Concentration for DDT and DDE (i.e. >1ppm) indicating their potential to affect vertebrate reproduction living in that habitat. DDT breaks down to DDE, an endocrine disruptor that competitively binds to androgen receptors, potentially affecting reproduction. We investigated the effects of DDE on steroidogenesis in male rodents. Rats were exposed daily to one of five doses of DDE (0, 10, 20, 50, 100 μg/L; N= 6/dose). After 4 weeks of exposure, serum testosterone (T) levels were significantly (i.e., p = to or < than 0.05) lower in animals exposed to the 10μg/L dose, but not reduced at the higher exposure doses. Interestingly, when testicular tissue from males from each exposure dose was challenged in vitro with luteinizing hormone (LH), it was again the 10μg/L dose group that exhibited a significantly reduced response to the LH. We then tested a two week daily exposure regime with a range of lower DDE doses (0, 0.001, 0.01, 0.1, 1, 10 μg/L; N=5/dose) on pre-pubertal vs. pubertal rats. Even with the lower dose exposure for a shorter period, pubertal rats exposed to the 0.1, 1 and 10 μg/L doses exhibited significantly lower serum T, significantly lower in vitro basal testicular T, and significantly lower in vitro testicular LH responsiveness. Pre-pubertal rats were even more sensitive, showing significant reductions in these same parameters even at the 0.001 and 0.1 μg/L doses.
