Effects of continuous and intermittent exposure of lactating mothers to aroclor 1242 on testicular steroidogenic function in the adult male offspring.

Polychlorinated biphenyls (PCBs) are worldwide pollutants and have caused hazardous effects on many animal species including humans. They have been detected in human milk and therefore exposure of newborns to PCBs is unavoidable if they are breast-fed. We present our findings on two experiments performed to test the effects of intermittent and continuous exposure of lactating rats to two different doses (80 microg and 8 microg) of Aroclor 1242 (a PCB congener) on testicular steroidogenic function of their adult male offspring. In experiment I, three groups of lactating dams received daily subcutaneous (SC) injections of either corn oil, 80 microg of Aroclor 1242 and 8 microg of Aroclor 1242 in corn oil, respectively. In experiment II, three groups of lactating dams received two SC injections per week of either corn oil or Aroclor 1242 (80 microg and 8 microg) in corn oil, respectively. Pups in all groups (n=8 per group) were weaned at day 21 and were raised on a normal diet until sacrificed at 90 days. Experiment I: Leydig cell number per testis was significantly (P<0.05) increased and the average volume of a Leydig cell was significantly (P<0.05) reduced in both groups of Aroclor-exposed rats compared to corn oil controls. Both doses of Aroclor resulted in reduced (P<0.05) serum testosterone levels compared to corn oil-treated controls. LH-stimulated testosterone production per testis and per Leydig cell was lower in Aroclor-exposed rats compared to controls. Experiment II: No changes were observed in Leydig cell size and number per testis among the three groups. Serum LH, testosterone and LH-stimulated testicular testosterone production in offspring rats of Aroclor-treated dams were not significantly different (P>.05) from the offspring of corn oil-treated dams. However, these parameters were lower in value in the offspring of dams treated with Aroclor 80 microg compared to the other two groups. LH-stimulated testosterone secretory capacity per Leydig cell was significantly lower in offspring of dams treated with Aroclor compared to controls. Serum T4 and T3 levels were not significantly different among the Aroclor-exposed and control rats in both experiments. These results demonstrate that continuous exposure of lactating mothers to 8 and 80 microg of Aroclor 1242 causes hypotrophy and malfunctioning of Leydig cells in the adult male offspring resulting in a hypoandrogenic status. Intermittent treatment of lactating mothers with 80 microg of Aroclor (but not with 8 microg of Aroclor) also produced malfunctioning of Leydig cells and a hypoandrogenic status in the absence of Leydig cell hypotrophy. However, the Aroclor 8 microg dose was ineffective to produce the above effects.