Binding of Thyroid Hormone to Freshwater Perch Leydig Cell Nuclei-rich Preparation and its Functional Relevance

概要

論文の詳細を見る
Leydig cells were isolated from the testis of a freshwater perch, Anabas testudineus, belonging to the prespawning stage of reproductive cycle. Cells were sonicated and a pure nuclei preparation was obtained for binding assay. Under optimum assay conditions of pH 7.4 at 30℃ and 90 min incubation binding of [^<125>I] 3,5,3'-triiodothyronine (T_3) to Leydig cell nuclei was saturable at 1.7 nmol/l concentration. A Scatchard analysis of T_3-binding exhibited a Kd of 26.8×10<-9>mol/l and a maximum binding capacity (B_max) as 1.66 pmol/mg DNA. Competitive inhibition studies demonstrated that binding of T_3 to Leydig cell nuclei is analogue specific. Biological relevance of T_3 binding to perch Leydig cell was evaluated by adding varied concentrations of T_3 to Leydig cell incubation (1×10^6 cells/incubation). Twenty five ng to 100 ng of T_3 resulted in a dose dependent increase in androgen release while 200 ng of T_3 had no additional effect over 100 ng under present incubation system. Stimulation of androgen release by T_3 was significantly inhibited (p<0.01) by cycloheximide. T_3 (100 ng/ml) increased protein synthesis in Leydig cell (70% as compared to control) which was significantly inhibited (p<0.01) by cycloheximide. Results indicate that binding of T_3 to Leydig cell of perch testis triggers the synthesis of a protein (or proteins) which in turn stimulates androgen release.
社団法人日本動物学会の論文
1993-06-15