Repeated exposures of the male Sprague Dawley rat reproductive tract to environmental toxicants: Do earlier exposures to di-(2-ethylhexyl)phthalate (DEHP) alter the effects of later exposures?

- Neither in utero nor juvenile (PND21-35) exposure to DEHP affected testis weight or histology.
- After in utero DEHP, however, subsequent juvenile exposure did result in significantly reduced testis weight and altered histology.
- Both in utero and juvenile exposures resulted in reductions in serum testosterone, but there was no effect of earlier on later exposure.
- We conclude that in utero exposure can, but will not necessarily, alter later exposure effects.

Although exposures to environmental toxicants occur throughout life, little attention has been paid to the possible effects of exposures early in life on later exposure effects. We asked whether DEHP administered in utero (GD14-parturition) affects how male rats respond to later exposures. Neither in utero nor juvenile (PND21-35) exposures to 100 mg/kg/day DEHP affected testis weight or histology as assessed on PND35. However, after in utero DEHP, subsequent juvenile exposure resulted in significantly reduced testis weight and altered testicular histology. Both in utero and juvenile exposures resulted in significant reductions in serum testosterone, but there was no effect of earlier on later exposure. Whether or not there had been in utero DEHP exposure, juvenile DEHP exposure had no effect on body, kidney or liver weights. These observations indicate that in utero exposure can, but will not necessarily, alter later exposure effects, with outcomes dependent upon endpoints measured and dose.