Short-term effects of genistein on gamete quality, steroidogenesis and histological changes in gonads in gibel carp, Carassius auratus gibelio

Authors: NEZAFATIANA, ELHAM - Kurdistan University Of Medical Sciences; ZADMAJID, VAHID - Kurdistan University Of Medical Sciences; Cleveland, Beth

Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2016
Publication Date: 1/5/2017
Citation: Nezafatiana, E., Zadmajid, V., Cleveland, B.M. 2017. Short-term effects of genistein on gamete quality, steroidogenesis and histological changes in gonads in gibel carp, Carassius auratus gibelio. Journal of the World Aquaculture Society. doi:10.1111/jwas.12399.

Interpretive Summary: Aquafeeds now contain high levels of plant-based proteins, particularly from soybeans. However, soy contains high levels of genistein, a phytoestrogen that is biologically active in mammals and fish. Genistein can mimic estrogen in fish, negatively affecting processes associated with sexual maturation and potentially inhibit reproductive capacity. In this study, sexually maturing male and female gibel carp were injected with genistein during sexual maturation and effects on reproductive capacity and offspring viability were determined. Genistein reduced sperm quality in males but did not affect gonad development in females, with the exception of reducing gonad weight. Genistein also reduced fertilization rates and reduced offspring viability 6 days post hatch. These results suggest that the genistein content of broodstock aquafeeds should be considered, particularly for the gibel carp, when reproductive success is a production goal. Therefore, development of aquafeeds with low concentrations of endocrine disruptors may be valuable to optimize reproductive success in the gibel carp and other fish species.

Technical Abstract: The objective of the present investigation was to determine effects of genistein or 17ß-estradiol (E2) on reproductive physiology in gibel carp, Carassius auratus gibelio, during prespawning phase. Maturing gibel carp of both sexes received intraperitoneal injections of E2 (10 µg/g body weight), one of two genistein doses (5 µg/g body weight, G5, or 50 µg/g body weight, G50), or the injection vehicle every other day for 10 days prior to spawning. Disruptions in reproductive capacity were determined by measuring indices of oocyte and sperm quality, histological analyses of gonad tissue, offspring viability, plasma metabolites and sex steroids. In males, E2 and genistein treatment reduced GSI and milt volume, while decreases in spermatozoa concentration and spermatocrit occurred only in E2 and G50-treated males. In females, genistein reduced GSI but did not affect fecundity and oocyte diameter. Histological examination of the testes indicate that E2 and genistein inhibited reproductive capacity via disruption of the spermatogenesis process in males, while there were no significant differences in histological endpoints in females. Genistein reduced fertilization rate and offspring viability at 6 days post hatch (dph). Plasma testosterone (T) and E2 decreased and increased, respectively, with E2 and G50 treatment in both sexes. Plasma T was reduced in G5-treated females. E2 and G50 treatment altered plasma metabolites phosphorous, calcium, cholesterol, and triglycerides. These findings indicate that genistein can negatively affect reproductive success in gibel carp, particularly males, suggesting that high dietary genistein may impair gonad development.