Effects of environmental endocrine disrupters on learning, memory and emotional behavior in the function of central nervous system

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2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is considered to be one of the most potent environmental endocrine disruptors. TCDD has been demonstrated to be a potent carcinogen and have immunotoxic effects. It is still uncertain, however, whether dioxins have also toxic properties in the central nervous system. Nonylphenol (NP), an alkylphenol polyethoxylates, is widely used as components of detergents, paints and many other synthetic products. This synthetic chemical is also considered to be an environmental endocrine disrupter that acts as an estrogenic substance. The present study was designed to investigate the effects of TCDD and NP on the central nervous system in male SD rats. Rats were received single i. c. v. administration of TCDD (100 ng/ 2μl) or NP (2 μg/ 2μl) at 8 weeks-old, and locomotor activities, food consumption and water intakes were measured. We also investigated effects of TCDD and NP on memory and emotional impairments in rats using 8 arm radial maze and Open-field apparatus, respectively. Under 12 hour-light/dark condition, the TCDD-, but not NP-treated rats exhibited higher locomotor activities without altering circadian rhythm. However, this dose of these endocrine disruptors did not affect the maze performance. These results suggest that TCDD may affect in a central nervous system to induce hyperactivity in rats.