Effects of estrogens in vitro and in vivo on cartilage growth in the tilapia (Oreochromis mossambicus).
To study the effects of estrogens on cartilage growth in the tilapia Oreochromis mossambicus, an epiceratobranchial cartilage radioisotope incorporation assay was employed to measure proteoglycan synthesis and prechondrocyte proliferation by incorporation of radiolabeled sulfate and thymidine, respectively. Cartilage explants were cultured with estrogens with or without recombinant bovine insulin-like growth factor-I (IGF-I). In vitro experiments using the natural teleost estrogen, 17beta-estradiol (E2), showed a trend toward inhibition of sulfate incorporation and an inhibition of thymidine incorporation at higher doses (10 micrograms/ml), but not at physiological levels. E2 also showed a trend toward inhibition of sulfate and thymidine incorporation in the presence of IGF-I. Similar results were found with other estrogenic compounds in vitro: ethinylestradiol, diethylstilbestrol (DES), genistein, and nonylphenol. Ethinylestradiol inhibited sulfate and thymidine incorporation at 1000 ng/ml in the presence of IGF-I. DES inhibited thymidine incorporation at 1000 ng/ml in untreated or IGF-I-exposed cartilage. Genistein inhibited sulfate incorporation at 100 micrograms/ml in IGF-I-exposed cartilage and inhibited thymidine uptake at 1, 10, and 100 micrograms/ml in untreated and IGF-I-exposed cartilage. Nonylphenol inhibited sulfate uptake at 100 microM in untreated and IGF-I-exposed cartilage. Nonylphenol alone at 10 and 100 microM inhibited thymidine uptake. In IGF-I-exposed cartilage nonylphenol inhibited thymidine uptake at 100 microM. Fish receiving estrogen injections (E2 or DES) in vivo at a concentration of 2 micrograms/g body weight showed increased sulfate incorporation by cartilage in vitro. Stimulation in vivo by estrogens, in contrast to the inhibition by high doses in vitro, may be a result of the influence of estrogen on pituitary growth hormone release.
Department of Integrative Biology, Group in Endocrinology and Cancer Research Laboratory, Berkeley, California 94720-3140, USA.
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Datuin
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Bern
D000818:Animals; D002356:Cartilage / Q000187:drug effects* / Q000254:growth & development*; D004054:Diethylstilbestrol / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D004997:Ethinyl Estradiol / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D013006:Growth Hormone / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D009924:Organ Culture Techniques; D010636:Phenols / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D017210:Tilapia / Q000254:growth & development*
D004967:Estrogens; D010636:Phenols; D011994:Recombinant Proteins; D004997:Ethinyl Estradiol; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D004054:Diethylstilbestrol; C025256:nonylphenol; D013006:Growth Hormone; D019833:Genistein