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(735) REGULATORY MECHANISM OF TOONA SINENSIS ON MOUSE LEYDIG CELL STEROIDOGENESIS. Poon, Song Ling1, Leu, Sew-Fen2, Sheu, San-Goun3, Huang, Bu-Miin1, 1 Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan2 National Laboratory Animal Breeding and Research Center, National Science Council, Taipei, Taiwan3 Department of Physiology, Kaoshiung Medical University, Kaoshiung, Taiwan ABSTRACT- Toona sinensis (TS), a kind of arbor, widely distributes nowadays in Asia. The leaves of TS have been used as an effective nutritious food in Chinese society for a long time. It was reported that TS can induce apoptosis of cancer cells, reduce plasma glucose in diabetic rats, and improve lipolysis of differentiated 3T3-L1 adipocyte and its uptake of glucose. It has also been shown that TS may increase dynamic activity of human sperm. Thus, we are interested to investigate whether Toona sinensis has any effect on mouse Leydig cell testosterone production, which correlates to sperm activity. Primary mouse Leydig cells were purified to conduct the in vitro experiments. Different concentrations of crude TS were added to primary mouse Leydig cells and the testosterone production was determined. The results showed that crude TS significantly inhibited both basal and hCG-stimulated testosterone productions in dose dependent manner, respectively (P<0.05). Crude TS also reduced the forskolin- and dbcAMP-stimulated testosterone production (P<0.05), which indicated that crude TS might affect protein kinase A (PKA) signal transduction pathway at the site after the formation of cyclic AMP. Moreover, TS inhibited Leydig cell steroidogenesis by suppressing the activity of steroidogenic enzymes including P450 side chain cleavage (P450scc) enzyme, 3 KEY WORDS: Leydig cell, Steroidogenesis, Toona sinensis, Testosterone |
-hydroxysteroid dehydrogenase (3
-HSD), 17
-hydroxylase, 20