Effect of ethinylestradiol on the reproduction and induction of vitellogenin and testis‐ova in medaka (Oryzias latipes)

Abstract

Mature medaka (Oryzias latipes) were exposed to ethinylestradiol (EE2) at measured concentrations of 32.6, 63.9, 116, 261, and 488 ng/L for 21 d under flow-through conditions. Effects on reproductive success of the fish as well as on gonadal condition and vitellogenin (VTG) induction were assessed. A significant decrease in fecundity was observed only at the highest EE2 concentration, whereas hepatic VTG concentration in males was increased at concentrations of 63.9 ng/L and greater. In addition, an intersex condition (testis-ova) of the gonad was observed in male medaka exposed to EE2 concentrations of > or = 63.9 ng/L. Overall, these results indicate that the lowest-observed-effect concentrations of EE2 based on reproduction versus induction of both VTG and testis-ova in the medaka were 488 and 63.9 ng/L, respectively. Thus, the physiological and histological measurements were approximately eightfold more responsive to the EE2 exposure than were overt reproductive effects. This suggests that the elevated VTG levels and testis-ova may not be definitely responsible for reproductive impairment of the fish.

Toxicity to early life stages and an estrogenic effect of a bisphenol A metabolite, 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene on the medaka (Oryzias latipes)

“…Gray et al (1999) also reported that exposure of male medaka to octylphenol during early life induce swollen abdomens and, subsequently, complete mortality before maturation. Similar pathological symptoms were observed in adult male medaka exhibiting increased VTG levels as a result of exposure to estrogenic compounds (Kang et al, 2002b;Seki et al, 2002). These authors suggested that general peritoneal edema related to ascites caused the mortality in males, because the male medaka has no natural process to excrete VTG accumulated in excess, causing pathological effects.…”

Biomonitoring Recycled Water in the Santa Ana River Basin in Southern California

“…Therefore, the exposure continued for an additional 1 mo in optimal reproductive temperatures (25-27°C) to prepare the fish for reproductive evaluation. In comparison with existing references, egg production (12-16 eggs/pair/d) in the control group of this study was well within the normal range of medaka fish reproduction (12-30 eggs/ pair/d) reported previously (Kang et al, 2002;Seki et al, 2002Seki et al, , 2005. The reduced egg production (0-9 eggs/pair/d) in E2-treated control and SAR-GW groups was similar to fish exposed to 27.9 ng/L E2 in a full-life-cycle exposure (0-5.4 eggs/pair/d) (Seki et al, 2005).…”

“…However, 20-30% mortality occurred in the E2-treated control and SAR-GW groups during the 1-mo static exposure. Although analytical confirmation of E2 exposure was not conducted, the occurrence of mortality, swollen abdomen, and lightened body color of the deaths indicated signs typical of E2 exposure in high concentrations or similar concentrations of chronic exposure (Kang et al, 2002;Seki, et al, 2002Seki, et al, , 2005.…”

Occurrence and distribution of endocrine-disrupting compounds in the Honghu Lake and East Dongting Lake along the Central Yangtze River, China

“…A decrease of testicular growth in male trout can be observed at the EEQ values in the range 10-100 ng L −1 (Harries et al 1997). The production of testis-ova in the testes of male medaka can be noticed at EEQ >100 ng L −1 level (Seki et al 2002). Hence, the EDCs in East Dongting Lake and Honghu Lake at specific sites may induce biological effects on the endocrine system of aquatic organisms, if the exposure to these levels is of sufficient duration.…”