17α‐Ethinylestradiol alters reproductive behaviors, circulating hormones, and sexual morphology in male fathead minnows (Pimephales promelas)

Abstract

Ecologically relevant indicators of endocrine disruption in fish must be linked with measures of reproductive success. The ability of male fathead minnows (Pimephales promelas) to compete for, maintain, and defend a spawning substrate is paramount to reproductive success. The present study quantified alterations in male fathead minnow reproductive behaviors after exposure to environmentally relevant concentrations (0, 10, 20, or 40 ng/L) of 17alpha-ethinylestradiol (EE2) for 21 d. A video-based behavioral quantification system examined changes in male-male competitive behaviors (chasing and head-butting) and ability of males to maintain spawning substrates (nibbling and scrubbing). Behaviors analyzed included time under the spawning substrate, frequency of substrate cleaning, and conspecific aggression. Plasma hormone levels (11-ketotestosterone [11-KT], testosterone, and estradiol [E2]), vitellogenin (VTG), secondary male characteristics (tubercle count and dorsal nape pad rank), gonadosomatic index (GSI), and gonad histology also were evaluated. Exposure to 40 ng/L of EE2 decreased the ability of exposed males to compete with control males for spawning substrates (p = 0.09). Furthermore, exposed males displayed reduced frequency of substrate cleaning activities as well as chasing male competitors (p < or = 0.05). 11-Ketotestosterone, testosterone, and E2 were lower, and VTG was notably higher, in EE2-exposed males compared with control males (p < or = 0.03). 17alpha-Ethinylestradiol exposure in males also was associated with reductions in tubercles; lower GSI, gonadal maturity ranks, and number of resorbed tubercles; and presence of an ovipositor (p < or = 0.001). These data reveal alterations in male reproductive behavior that coincide with decreased hormone levels and secondary sex characteristics. Behavioral endpoints to discern potential ecological consequences in fish exposed to low concentrations of endocrine-disrupting chemicals may provide sensitive and functional indices of effect.

Environmentally relevant exposure to 17α-ethinylestradiol affects the telencephalic proteome of male fathead minnows

“…In male goldfish, Martyniuk et al (2006) observed a significant 10-fold reduction in plasma E 2 and a 3-fold decrease in plasma T after 2 weeks exposure to 30 ng EE 2 /L. Male FHMs treated with 10, 20 or 40 ng EE 2 /L for 21 days showed significant decreases in E 2 , T, and 11-ketotestosterone of approximately 2-fold, 4-fold, and 10-fold respectively (Salierno and Kane, 2009). The relatively rapid inhibition of sex steroids by EE 2 has also been observed in female zebrafish ( Danio rerio ).…”

Developmental exposure of zebrafish (Danio rerio) to 17α-ethinylestradiol affects non-reproductive behavior and fertility as adults, and increases anxiety in unexposed progeny

“…The qPCR was performed using BioRad C1000 Touch Thermal Cycler, CFX96 Real-Time System, with the oligonucleotide primers Vtg2 5′-GGTGACTGGAAGAT CCAAG-′3 and Vtg2 3′-TCATGCGGCATTGGCTGG-′5 (Fernandez-Galaz et al, 1997). The samples were normalized against the mRNA expression of the housekeeping gene 18 s RNA (18a small ribosomal unit RNA) as internal reference, using the following primers: 18s 5′-AATGTCTGCCCTATCAACTTTC-′3 and 18s 3′-TGGATGTGGTAGCCGT TTC′5 (Salierno and Kane, 2009). All primer sets were tested for specificity and qPCR was performed using iTaq Universal Sybr Green Supermix (BioRad) according to the program previously described by ReyhanianCaspillo et al (2014).…”

Microbiological and Toxicological Assessment of Pharmaceutical Wastewater from the Lagos Megacity, Nigeria

“…The fate of pharmaceutical effluents in aquatic environments is increasingly eliciting scientific inquiry owing to recent findings of their effects in biological systems [1]. Nigeria has a few pharmaceutical companies most of which are situated in Ogun and Lagos States in the country's south western region, discharging effluents into neighbouring rivers, creeks, and lagoons.…”