Levels of 17β estradiol, vitellogenin, and prostaglandins during the reproductive cycle of Oreochromis niloticus

Abstract

ABSTRACT. Circulating levels of estradiol, vitellogenin and prostaglandins could be references of oocytes quality in the aquaculture industry. This study evaluated the performance of 17β-estradiol (E2) and vitellogenin (Vtg) levels in plasma and prostaglandins in oocytes (PGE 2) during the reproductive period of Oreochromis niloticus in a commercial farm in Ecuador. Adults fish females were treated with estradiol-synthetic (ES) and tilapia pituitary extracts (TP) during 25 days. For quantification of E2 and PGE 2, an enzyme-linked immunosorbent assay (ELISA) was used, while for Vtg relative quantification a Western blot analysis was performed. Circulating E2 concentrations were different during the first week of follow-up (P < 0.05) resulting in different levels of Vtg per treatment (P < 0.05) affecting on gonadal growth. The ovaries had an asynchronous development, where the mature oocytes proportions were higher with ES and TP than control. Relative fecundity was different between treatments (P < 0.05), where TP generated 15.7 ± 5.8 oocytes per g of spawning female. Furthermore, concentrations of PGE 2 were different between treatments (P < 0.05). The information reported in this study will be useful to improve the reproduction methods and have some biological signals before ovulation in tilapia commercial culture.

Gonadosomatic-hepatosomatic index and sex ratio of beardless barb (Cyclocheilichthys apogon) from Lebak Kalong Floodplain, Ogan Komering Ilir, South Sumatra, Indonesia

“…The HSI is related to the GSI because of the vitellogenesis process that synthesizes vitelogenin (Hismayasari et al, 2015). In fish, vitelogenin is a yolk precursor synthesized in the liver and indicated by estradiol 17β (Fernandes, 1994;Hara et al, 2016;Ortiz-Tirado et al, 2017). Vitelogenin is secreted in the blood and transported to oocytes, causing yolk accumulation.…”

Transcriptomes of testis and pituitary from male Nile tilapia (O. niloticus L.) in the context of social status

“…Data from a recent study in O . niloticus further suggests that PGE2 levels are sensitive to estrogenic compounds and pituitary extract [ 204 ]. Systematic research into the role of PGE and its receptors in male reproduction of fish is still scarce but given the circumstantial evidence provided above, we could speculate that in the context of social dominance, PGE2 receptor expression is stimulated by sex steroids and gonadotropins and in turn modulate steroidogenesis and stress response.…”

Steroid Profiles of Wild Terror Green (Andinoacara rivulatus) Associated with Gonadal Histology in the Baba River, Ecuador

“…In this sense, it can be speculated that the response generated in follicular cells of ovary does not depend only on the availability of circulating peptide hormones, but also on the nearby factors such as light and temperature. In addition, it would affect the seasonality and concentration of E2, and thus the concentrations of Vitellogenin (Vtg) in plasma, prolongation of gonadal development during this period [10]. Consequently, these aspects are related to the low concentrations detected in A. rivulatus.…”

“…However, many relevant questions about reproductive biology, especially about the cycle of sexual maturation and reproductive endocrinology, remain undisclosed [6]. The hypothalamicpituitary-gonad (HPG) axis is the central paradigm in the study of the reproduction biology, which can be affected by environmental, endocrine, paracrine, autocrine, and intracrine factors [8]- [10].…”

“…They can affect the quality of oocytes due to different structures of the glycosidic residues in the heterodimers that constitute follicle-stimulating hormone (FSH), especially in the β subunit, which alters the response of the steroidogenic signal for binding to its specific membrane receptor. In farming green terrors, an alternative for reproductive management is the use of tilapia pituitary, which has a homology and provides interesting results in in vitro and in vivo cultures in tilapia [10]. Another is the use of fortified foods to achieve high productivity and controlled spawning of captive wild breeders [6].…”