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Sexually dimorphic behavioral responses to prenatal dioxin exposure
Rieko Hojo1, Sander Stern, Grazyna Zareba
1Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
Environmental Health Perspectives
|March 8, 2002
Summary
Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) altered operant behavior in rats, showing sex-specific effects. Benchmark doses for TCDD
Area of Science:
- Toxicology
- Neuroscience
- Environmental Health
Background:
- 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental pollutant.
- TCDD exposure can lead to various adverse health effects.
- Understanding TCDD's impact on behavior is crucial for risk assessment.
Purpose of the Study:
- To investigate the dose-dependent effects of TCDD on operant behavior in Sprague-Dawley rats.
- To determine if TCDD exposure elicits sexually dimorphic behavioral responses.
- To calculate benchmark doses (BMDs) for TCDD based on behavioral changes.
Main Methods:
- Pregnant rats received single oral doses of TCDD (0-180 ng/kg) on gestation day 8.
- Offspring were trained on operant schedules (Fixed Ratio and Differential Reinforcement of Low Rates).
- Sex-specific response rates were analyzed to calculate ED(01) and ED(10) benchmark doses.
Main Results:
- TCDD exposure resulted in sexually dimorphic behavioral patterns: males showed decreased response rates, while females exhibited increased rates.
- The calculated mean ED(10) for the male-female difference in FR rate was 2.77 ng/kg.
- The calculated mean ED(10) for the male-female difference in DRL rate was 2.97 ng/kg.
Conclusions:
- TCDD exposure significantly alters operant behavior in a sex-dependent manner.
- Benchmark doses derived from behavioral endpoints are below estimated human body burdens.
- These findings highlight TCDD's neurobehavioral toxicity and inform risk assessment for human exposure.