Organizational effects of diethylstilbestrol on brain vasotocin and sexual behavior in male quail

In Japanese quail, we previously described a sexual dimorphism of the parvocellular vasotocin system of the limbic region that, as the reproductive behavior, is steroid-sensitive and is organized during embryonic life by the exposure to estradiol. We verified in this study whether diethylstilbestrol, a chemical xenoestrogen, has analogous organizational effects on the vasotocin system of limbic regions and on copulatory behavior of male Japanese quail. We injected in the yolk sac of 3 day-old quail embryos diethylstilbestrol or estradiol benzoate (a treatment which suppresses male copulatory behavior in adulthood and reduces vasotocin innervation), or sesame oil (control). No further hormonal manipulations were performed after hatching. Sexual behavior was recorded in males at the age of 6 weeks. Estradiol- and diethylstilbestroltreated males exhibited a total suppression of copulatory behavior. After behavioral tests, all males were sacrificed and brain sections processed for vasotocin immunocytochemistry. Significant decrease in the density of vasotocin immunoreactivity was detected in the medial preoptic nucleus, in the bed nucleus of stria terminalis, and in the lateral septum of diethylstilbestrol-treated males. The magnocellular vasotocin neurons were, in contrast, not affected. In conclusion, the present data demonstrate that embryonic treatment with diethylstilbestrol induces a full sex reversal of behavioral phenotype as well as a significant decrease of vasotocin expression in the preoptic-limbic region in male Japanese quail. Therefore, the parvocellular vasotocin system could represent an optimal model to investigate the effects of pollutants on neural circuits controlling reproductive functions. (c) 2004 Elsevier Inc. All rights reserved.