Effects of estrogens in environmentally relevant concentrations on kiss2 and kiss2rb expression in pejerrey fish brain, pituitary and testes.

OSWALDO TOVAR; ANGELA GÁRRIZ; RENATA MENÉNDEZ-HELMAN; PAMELA DEL FRESNO; LEANDRO A. MIRANDA; GUSTAVO M. SOMOZA

Buenos Aires

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

SETAC-LA

Environmental estrogenic compounds can interfere with the endocrine systemand adverse developmental and reproductive effects in animals. Estradiol (E2)and 17α-ethynylestradiol (EE2) contribute to the estrogenic activity in water bodies all over the world. During the last years, a more inclusive concept hasemerged: neuroendocrine disruption, in order to include the full breadth ofintegrative physiology. So, we aimed to study the neuropeptide kisspeptin(kiss), known to control reproductive function in vertebrates. For example, inDanio rerio and Carassius auratus kisspeptin mRNA expression in the brain isincreased after E2 treatments and putative binding sites for estrogen receptors(ERs) have been characterized in kisspeptin and kisspeptin (kissr) receptorpromoter regions. In most teleost species, the kisspeptin system is composed bytwo ligands (kiss1 and kiss2) and two receptors (kiss2rb and kiss3rb); and it isknown that kiss2/kiss2rb are related to gonadal maturation. In this context, themain of the present study was to evaluate the effects of E2, EE2 and theirmixture on kiss2/kiss2rb mRNA expression in the Brain-Pituitary-Testicularaxis of pejerrey. To accomplish this goal, five adult males were maintained in60 L tanks during 14 days, using a static exposure system (by duplicates). Fishwere exposed to 350 ng/L of E2 and 45 ng/L of EE2, and the mixture of bothestrogens at the same concentrations, and the steroids were added every twodays in order to keep their concentration constant. At the end of the exposure,fish were anesthetized and sacrificed. A brain section (from the optic tectum tothe inferior lobe of the hypothalamus), the pituitary gland and the testes weredissected, total RNA obtained and cDNA was synthetized by reversetranscription reaction. Kiss2 and kiss2rb expression was measured by RTqPCR,using ß-actin and elongation factor 1 as reference genes. The estrogensmixture induced a rise of kiss2 and kiss2rb mRNA expression in the brain,compared to the other treatments. No significant differences in kiss2 or kiss2rblevels were observed in the pituitary gland and testes. These results suggest that estrogenic compounds have a differential action on kiss2/kiss2rb expressiondepending on the tissue and show, that kisspeptin is a target of endocrinedisruption. Further studies must be done to clarify this action, probablymediated by ER response elements in pejerrey as it has already been reportedfor other teleost.