Reproductive, neuroendocrine, and immune consequences of acute exposure to2,3,7,8-tetrachlorodibenzo-p-dioxin in the Siberian hamster

The present study tested the hypothesis that acute treatment with 2,3,7,8-t etrachlorodibenzo-p-dioxin (TCDD) impairs fertility, disrupts the nocturnal melatonin rhythm, and suppresses lymphocyte function. Adult Siberian hamst ers administered 2 or 100 mu g TCDD/kg body weight/0.2 ml sesame oil had a delayed latency to first litter and an increased adult mortality compared t o hamsters given 0.1 mu g/kg or vehicle. Within 75 days of TCDD treatment, full reproductive capabilities were achieved. Moreover, the nocturnal melat onin rhythm was not disrupted in adults administered TCDD or in their proge ny. Lymphocyte activity varied with respect to time of day and treatment. L ymphocyte proliferation was enhanced at night irrespective of TCDD treatmen t; during the day, 2 wk after the 2-mu g/kg treatment, blastogenesis was re duced compared to that in the 0.1-mu g/kg group or in vehicle-treated contr ols. In contrast, TCDD did not affect the mixed lymphocyte reaction in resp onse to allogeneic antigen when assessed at 2 and 20 wk post-treatment. Thu s, findings indicate that TCDD produced acute effects on fertility, mortali ty, and systemic lymphocyte proliferation, but long-lasting effects on spec ific aspects of reproductive, neuroendocrine, and immune cell functions wer e not observed.