%A"Lichtensteiger, W" %A"Faass, O" %A"Ceccatelli, R" %A"Schlumpf, M [Zurich Univ. (Switzerland). Inst. of Pharmacology and Toxicology]" %D2004 %I; Technische Univ. Berlin (Germany). Inst. fuer Technischen Umweltschutz %2Bundesmin. fuer Umwelt, Naturschutz und Reaktorsicherheit, Bonn (Germany) %J[] %K63 RADIATION, THERMAL, AND OTHER ENVIRONMENTAL POLLUTANT EFFECTS ON LIVING ORGANISMS AND BIOLOGICAL MATERIALS, BROMINATED AROMATIC HYDROCARBONS, POLYCHLORINATED BIPHENYLS, ONTOGENESIS, PRENATAL EXPOSURE, RATS, GENE REGULATION, BRAIN, ESTROGENS, BEHAVIOR, FEMALES %PMedium: ED; Size: page(s) 3915-3920 %TDevelopmental exposure to PBDE 99 and PCB affects estrogen sensitivity of target genes in rat brain regions and female sexual behavior %XWe recently reported effects of PBDE99 (2,2',4,4'5-pentabromoBDE) on sexual differentiation processes in rat reproductive organs and central nervous system. These studies were prompted by reports on an increase of PBDE levels in human milk, an indicator of the body burden of pregnant women and of potential exposure of the nursing infant, during the last decade. Even higher human adipose tissue and milk levels were reported for North America. PBDE99 is present in human and animal samples and exhibits developmental neurotoxicity in mice. The developing brain is subject to the organizing action of estradiol locally formed from circulating testosterone, and thus represents a target for endocrine active chemicals. One molecular mechanism by which chemicals may interfere with sexual brain differentiation, may be a change in the expression of sex hormone (estrogen)-regulated genes. Such effects may manifest themselves in mRNA expression levels, or in the sensitivity of the genes to estrogen. In order to detect alterations of the latter, more subtle parameter, we have conducted experiments in developmentally chemical-exposed rat offspring that were gonadectomized in adulthood and injected with a challenge dose of estradiol. Effects of PBDE99 were compared with those of a commercial PCB mixture, Aroclor 1254, which had previously been found to influence sexual brain differentiation. We analyzed the expression of estrogen-regulated genes in ventromedial hypothalamus (VMH) and medial preoptic area (MPO), two brain regions that are part of a network involved in the integration of environmental cues, sexual behavior and gonadal function. Since prominent changes were observed in VMH which is particularly important for female sexual behavior, the study was completed by a behavioral analysis. %0Conference %NETDE-DE-1546;Other: ISBN 3-928379-30-5; TRN: DE07G1079 %1 %CGermany %Rhttps://doi.org/ Other: ISBN 3-928379-30-5; TRN: DE07G1079 DE %GEnglish