Abstract
5 alpha-dihydrotestosterone specific binding in prepubertal rabbit cartilage cells and variation of 5αreductase activity with the age of the donor animals.
Recently, we reported that prepubertal male rabbit cartilage tissue and cells are able to convert Testosterone (T) into its major active metabolite 5αdihydroT (DHT) (Takahashi et al. Mol. Cell Endocr. 35:15,1984).The purpose of the present work was 1)to determine wether such cartilage cells contain specific binding sites for DHT 2)to study the variation of the 5αreductase activity at different ages from birth to post puberty.The 3H-DHT and 3H-R1881 binding studies were performed in total cartilage cell proteins prepared in 0.4 M KCl Tris buffer.After two hours incubation at 15° bound and free binding sites were separated by charcoal or PEG adsorption and analyzed by Scatchard plots.The binding capacity was 2-7 pmoles/mg protein with low affinity (KD=0.2-5×10−15M).The cartilage 5αreductase activity was studied by incubating AR cartilage slices in the presence of 3H-T (90 nM).Radiolabelled steroids were then extracted from tissue and incubation medium, analysed by celite chromatography and the amount of newly formed 3H-DHT was quantified.During the first 10 days after birth, AR cartilage 5α reductase activity was 3.55±1.05 pmoles/mg tissue.It increased pro gressively to reach 51.5±2.5 pmoles/mg tissue in 20 to 50 day old animals and then came down to the starting levels. The maximum activity thus observed at puberty when androgen plasmatic concentration rises in male rabbits could be related to variations in andro gen receptors.
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Corvol, M., Dayani, N. & Bok, S. 5 alpha-dihydrotestosterone specific binding in prepu bertal rabbit cartilage cells and variation of 5αreduc tase activity with the age of the donor animals. Pediatr Res 18, 1213 (1984). https://doi.org/10.1203/00006450-198411000-00075
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DOI: https://doi.org/10.1203/00006450-198411000-00075