Effect of dietary administration of letrozole and tamoxifen on gonadal development, sex differentiation and biochemical changes in common carp (Cyprinus carpio L.)

Abstract

The effect of letrozole and tamoxifen on the specific growth rate (SGR; % day(-1)), gonado-somatic index (GSI), total haemoglobin (g%), gonadal and serum protein as well as lipid, sex differentiation and 17β-oestradiol levels were studied in sexually undifferentiated Cyprinus carpio fingerlings 30 days post fertilisation (30 dpf) for 60 days. Results showed decreased GSI with tamoxifen treatment whereas letrozole increased it. There were reduced protein, lipid, triglyceride and cholesterol levels after treatment with tamoxifen and letrozole during gonadal development. Tamoxifen (200mgkg(-1) feed) induced 82.5% masculinisation, whereas letrozole in the same dose produced 98.5% males. Gonadal 17β-oestradiol significantly declined from 86.0±1.41pg per 100mg (control) to 45.5±1.94pg per 100mg with tamoxifen and 36.0±0.72pg per 100mg with letrozole treatment. Similarly, serum 17β-oestradiol levels also decreased after tamoxifen and letrozole treatments. Testicular development in 37.8% of fish treated with tamoxifen and letrozole was found to be more advanced (spermatocytes) than in the control (spermatogonium); however, there was reduced ovarian growth and increased atresia. It was concluded that letrozole and tamoxifen both significantly affect sex differentiation and gonadal maturity in C. carpio leading to the production of sex-reversed males, yet the effect of letrozole was more potent.

Integrated assessment of wastewater treatment plant effluent estrogenicity in the Upper Murray River, Australia, using the native Murray rainbowfish (Melanotaenia fluviatilis)

“…Although no significant vitellogenin induction was observed, there was significant suppression of spermatogenesis in 50% and 100% EFF-exposed fish after 28 d of exposure and a nonsignificant trend for dose-dependent suppression of spermatogenetic activity in EFF-exposed fish after 14 d (Figure 4). Although the reproductive response to environmental estrogens has not been studied previously in Murray rainbowfish, spermatogenesis in fish is sensitive to diverse environmental contaminants, including estrogenic and anti-estrogenic EACs [7,60]. The inhibition of gonadal function observed in this experiment may be related to the strong anti-estrogenic activity of the WWTP effluent detected by the in vitro yeast estrogen screen assay, and suggests that even the effluent from an advanced WWTP may adversely impact fish reproductive health.…”

Tamoxifen persistently disrupts the humoral adaptive immune response of gilthead seabream (Sparus aurata L.)

“…Tmx has been recommended for use as a reference compound in fish testing in terms of understanding the potential impact of selective estrogen receptor modulators (SERMs) in aquatic life (Ankley et al, 2002). Previous studies in fish have analyzed the impact of dietary Tmx in fish reproduction (Mandiki et al, 2005;Singh et al, 2015).…”

The combined effects of temperature and aromatase inhibitor on metamorphosis, growth, locomotion, and sex ratio of tiger frog (Hoplobatrachus rugulosus) tadpoles

“…Early studies have reported interactions between temperature and steroids, with resulting effects on amphibian larval growth, development, and metamorphosis (Hayes, Chan & Licht, 1993); however, the effects of these interactions on amphibian sex development have rarely been assessed. Aromatase inhibitors do not exist in nature, but they have become more widely used in recent years because they can affect the levels of endogenous steroid hormones and are associated with better hormonal regulation than exogenous steroid hormones (Miyata & Kubo, 2000;Olmstead et al, 2009;Shen et al, 2013;Singh et al, 2015). Given the state of research on aromatase inhibitors and the potential effects of steroids on anuran larval growth and development, an investigation of the interactive effects of temperature and aromatase inhibitors on growth and sex development is warranted.…”