Effects of the insecticide bromophos-ethyl and -methyl on the expression of oestrogen receptor α and β in the anal fins of thai medaka, oryzias minutillus (Beloniformes: Adrianichthyidae)

Abstract

Bromophos-ethyl and bromophos-methyl are agricultural insecticides that occur in natural environment. The Oryzias fish is the genus of tiny fish that is known to be one of model organism in the biological fields such as endocrinology. The anal fins exhibit a secondary sex character controlled by sex steroid hormones and assume a sensitive indicator. Therefore, the aim of this study was to investigate the effects of the insecticide bromophos-ethyl and methyl on the expression levels of the Estrogen Receptors (ER) α and β in the anal fins of Thai medaka (O. minutillus). Adult fish which were exposed to 0.01, 0.1 and 1 μg mL-1 of each insecticide were measured the ER levels by using a semi-quantitative PCR analysis. In males, the ER α and β expression levels in the anal fins were increased in response to treatment with both insecticides. In females, the ER α levels were also increased in response to bromophos-methyl. In contrast, the ER β levels in females were unaffected by exposure to bromophos-ethyl. Based on these results, it suggests that the effects of xenoestrogenic bromophos-ethyl and -methyl may alter in the patterns of gene expression mediated by ER α and β and depending on the sex-specific characteristics of the anal fin in Thai medaka. © 2014 Academic Journals Inc.