Sexual behavior in Japanese quail as a test end point for endocrine disruption: effects of in ovo exposure to ethinylestradiol and diethylstilbestrol.

Abstract

Chemicals having a capacity to disturb the endocrine system have attracted considerable interest during recent years. There is a shortage of well-characterized in vivo tests with which to study such disturbances in different classes of vertebrates. In the present study, test end points related to reproduction in the Japanese quail were used to examine the estrogenic activity of chemicals. The synthetic estrogens ethinylestradiol (EE(2)) and diethylstilbestrol (DES), used as model compounds, were injected into the yolk of embryonated eggs. After the birds had been raised to sexual maturity, we examined sexual behavior, plasma testosterone concentrations, and testis morphology in adult males. The lowest doses resulting in a significantly depressed male sexual behavior were 6 ng/g egg for EE(2) and 19 ng/g egg for DES. Testis weight asymmetry was increased at 6 ng EE(2)/g egg, but DES had no effect at any treatment level. The area of the androgen-dependent cloacal gland was significantly reduced at 57 ng DES/g egg. No effects on plasma testosterone concentration or body weight following exposure to EE(2) or DES were observed at any dose level. Depressed male sexual behavior was the most sensitive of the end points studied, and we suggest that this ecologically relevant end point be included in avian in vivo testing for neuroendocrine disruptors.ImagesFigure 1Figure 2

The parvocellular vasotocin system of Japanese quail: a developmental and adult model for the study of influences of gonadal hormones on sexually differentiated and behaviorally relevant neural circuits.

“…Some of these compounds (e.g., bisphenol A or ethinylestradiol) are known to alter sexual behavior or reproduction in mammals as well as in birds (74). Halldin et al (75) described a significant reduction of sexual behavior in quail exposed to the environmental pollutant ethinylestradiol during embryonic development. It therefore seems of interest to investigate alterations of neural circuits that could influence these behavioral (and physiological) changes.…”

The effects on steroidogenesis and histopathology of adult male Japanese quails (Coturnix coturnix japonica) testis following pre-pubertal exposure to di(n-butyl) phthalate (DBP)

“…Elsewhere, Gray et al (1982) observed a decrease in testicular weight. Embryonic exposure to xenoestrogens produced a reduction in the growth of the cloacal gland at sexual maturity in male Japanese quail (Adkins, 1979;Halldin et al, 1999;Halldin et al, 2003). This effect may be induced by activation of ERα since propyl pyrazol triol (PPT) treatment during quail embryo development significantly reduced the cloacal gland area in sexually mature males (Mattsson et al, 2008b).…”

Effect of estradiol-17β on follicle-stimulating hormone secretion and egg-laying performance of Japanese quail

“…In many studies, male and female quail embryos have been treated with E 2 , E 2 esters and synthetic estrogen analogues to study their effect on development of reproductive tract, sexual maturation, behavior and egg-laying performance (Aste et al, 1991;Halldin et al, 1999;Berg et al, 2001). There is a limited number of studies concerning the effect of E 2 on Japanese quail egg production.…”

“…However, higher physiologic doses of E 2 stimulates the pituitary secretion of LH and FSH, which in turn stimulate gonadal function. However, addition of E 2 to pituitary cell culture inhibited or stimulated spontaneous secretion of FSH, depending on the species (Miller and Wu, 1981).In many studies, male and female quail embryos have been treated with E 2 , E 2 esters and synthetic estrogen analogues to study their effect on development of reproductive tract, sexual maturation, behavior and egg-laying performance (Aste et al, 1991;Halldin et al, 1999;Berg et al, 2001). There is a limited number of studies concerning the effect of E 2 on Japanese quail egg production.…”