PARENT SESSION

(57) EMBRYONIC EXPOSURE TO ENVIRONMENTAL ENDOCRINE DISRUPTORS IMPAIRS ADULT REPRODUCTIVE BEHAVIOR AND HYPOTHALAMIC NEUROENDOCRINE SYSTEMS.

Ottinger, Mary Ann ¹, Quinn, Jr, Michael¹, Lavoie, Emma¹, McKernan, Moira¹, Thompson, Nichola¹, Barton, Ashley¹, Abdelnabi, Mahmoud¹, ¹ University of Maryland, College Park, MD

ABSTRACT- Environmental chemicals (EDCs) are receiving attention for their capacity to interact with endogenous endocrine systems. However, most regulatory testing paradigms depend on gross measures, such as fertility or egg production and neglect to evaluate more subtle effects on neuroendocrine systems. Of particular concern are potential effects of EDCs on neural targets from embryonic exposure and subsequent impact on reproductive function in adults. Effects of estrogen- and androgen-active compounds were investigated on hypothalamic neural systems in the hatchling and adult. Fertile quail eggs (n=85-95/group) were injected with 20 l sesame oil (control), 17 estradiol, trenbolone, or DDE into the yolk at either embryonic day 4 or 11. These days were chosen to coincide with gonadal differentiation or sexual differentiation of hypothalamic systems. Birds were either raised to adulthood or sampled at hatch. Nontraditional measures for endocrine disruption were evaluated, including hypothalamic aromatase (AROM), catecholamines, and GnRH-I. Reproductive maturation and copulatory behavior were measured in birds that were raised. Results showed EDC exposure impaired reproductive behavior and altered rates of sexual maturation. Estradiol treatment increased AROM in hatchlings injected at E11; androgenic EDCs did not affect AROM. Catecholamines were altered by the treatments, especially the higher doses of EDCs and the differences were most apparent in adults. GnRH-I was sexually dimorphic with small effects from trenbolone that was observed in adults. In total, there were effects of EDCs that were visible in hatchlings in some variables. These effects become more pronounced in the sexually mature individuals, suggesting that chemical exposure of the embryo is expressed to some degree immediately (observable in the hatchling), but is more clinically apparent during activation of the reproductive neuroendocrine system. Finally, hypothalamic neurotransmitters that modulate reproductive function may provide valuable indices of endocrine disruption associated with later consequences of embryonic exposure to EDCs. Supported by EPA R826134010 (Star Grant), NSF 9817024, and EPA R-2877801(MAO).

KEY WORDS: environmental chemicals, endocrine disruption, neuroendocrine systems, GnRH