LAUSR

The pituitary gland is a central regulator of reproduction, producing two gonadotropins, follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh), which regulate gonadal development, sex steroid synthesis and gamete maturation. This study sought to optimize an in vitro test system using pituitary cells isolated from previtellogenic female coho salmon and rainbow trout, focusing on fshb and lhb subunit gene expression. Initially, we optimize culture conditions for duration and benefits of culturing with and without addition of endogenous sex steroids (17β-estradiol [E2] or 11-ketotestoerone) or gonadotropin releasing hormone (GnRH). Results suggested culturing with and without E2 was valuable as it could mimic the (+) feedback effects on LH that is observed from in vivo studies. After optimizing assay conditions, a suite of 12 contaminants and other hormones was evaluated for their effects on fshb and lhb gene expression. Each chemical was tested at 4-5 different concentrations up to solubility limitations in cell culture media. Results indicated more chemicals altered lhb synthesis than fshb. The more potent chemicals were estrogens (E2 and 17α-ethynylestradiol) and the aromatizable androgen testosterone, which induced lhb. The estrogen antagonists 4-OH-tamoxifen and prochloraz decreased the E2-stimulated expression of lhb. Among several selective serotonin reuptake inhibitors tested, the sertraline metabolite norsertraline was notable for both increasing fshb synthesis and decreasing the E2 stimulation of lhb. These results indicate that diverse types of chemicals can alter gonadotropin production in fish. Further, we have shown that pituitary cell culture is useful for screening chemicals with potential endocrine disrupting activity and can support development of quantitative adverse outcome pathways in fish.