In teleosts, steroid synthesis is mainly controlled by hypothalamus-pituitary-gonadal (HPG) axis. A number of compounds released into aquatic environment that have potential to interfere with fish endocrine system. These endocrine disturbing chemicals (EDCs) can disturb piscine endocrine system at every level by interference with HPG axis. Bisphenol-A (BPA) is an estrogenic endocrine disrupting chemical used in production of polycarbonate plastic and epoxy resins. The present study was aimed to investigate the effects of BPA on level of steroid and thyroid hormones in a fresh water cyprinid, Catla catla. Virgin female C. catla, two years of age, were exposed to graded concentration of BPA (10,100 and 1000µg/l) for 14 days, after stipulated time fish were bled and hormone titers were estimated. Plasma level of estradiol significantly increased in response to 100 and 1000µg/l BPA exposure. A significant decrease in plasma testosterone, triiodothyroxin (T3), thyroxin (T4) was recorded after 14 days BPA exposure.  Plasma follicle-stimulating hormone (FSH) levels showed significant increase only at 10μg/l BPA exposure. Significant increase in plasma luteinizing hormone (LH) was observed in fish exposed to 1000µg/l of BPA. Change in plasma sex hormone and gonadotropin levels may cause subsequent reproductive dysfunction by interfering with the feedback regulatory mechanisms of the HPG-axis.

Key words: Bisphenol-A (BPA), Catla catla, Endocrine disruption, Gonadotropins, Sex steroids, Thyroid hormones