Evidence for nitrite reductase activity in intact mouse Leydig tumor cells
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摘要Nitric oxide (NO) supposedly derived via L-arginine-NO synthase (NOS) pathway has been implicated in inhibiting steroidogenesis by binding the heme moiety of steroidogenic enzymes. Previously, nitrite, and to a lesser extent nitrate ions inhibited steroidogenesis via NO by hitherto unknown reduction mechanism. Recently, a putative mammalian nitrite reductase activity ascribed to complex III of mitochondrial respiratory chain complexes (MRCC) has been reported, where MRCC inhibitors reduced NO production from nitrite variably. We thus studied the effects of MRCC inhibitors on testosterone production in mouse Leydig tumor cells (MLTC-1) without (basal) or with human chorionic gonadotropin (hCG) stimulation. In stimulated MLTC-1, MRCC inhibitors decreased testosterone production, order being: complex III (antimycin A and myxothiazol) > complex I (rotenone) > complex II (thenoyltrifluoroacetone), while cAMP production increased inversely. In unstimulated MLTC-1, MRCC inhibitors in same order, increased basal testosterone production, which correlated inversely with the percentage inhibition of NO production, with one exception; while antimycin A did not inhibit NO production in the nitrite reductase study mentioned above, it increased basal testosterone production in the present study. While MLTC-1 expressed mRNA for endothelial and neuronal, but not inducible NOS, various stimulators and inhibitors of L-arginine-NOS pathway had no effect on basal testosterone production in MLTC-1 or fresh Balb/c Leydig cells. Moreover, hCG increased nitrate uptake into MLTC1, which suggests the gonadotropin aids nitrite and nitrate ions in their steroidogenesis inhibitory activity. In conclusion, this study supports the existence of a surrogate mammalian nitrite reductase and the dormancy of L-arginine-NOS pathway in MLTC-1.
著者Panesar NS, Chan KW
期刊名稱Steroids
出版年份2006
月份11
日期1
卷號71
期次11-12
出版社ELSEVIER SCIENCE INC
頁次984 - 992
國際標準期刊號0039-128X
電子國際標準期刊號1878-5867
語言英式英語
關鍵詞chloride channel; gonadotropins; nitrate uptake; nitric oxide; SPQ fluorescence; steroidogenesis
Web of Science 學科類別Biochemistry & Molecular Biology; BIOCHEMISTRY & MOLECULAR BIOLOGY; Endocrinology & Metabolism; ENDOCRINOLOGY & METABOLISM

上次更新時間 2021-11-05 於 01:15