Stimulatory effect of lactate on testosterone production by rat Leydig cells.
Previously we found that the increased plasma testosterone levels in male rats during exercise partially resulted from a direct and luteinizing hormone (LH)-independent stimulatory effect of lactate on the secretion of testosterone. In the present study, the acute and direct effects of lactate on testosterone production by rat Leydig cells were investigated. Leydig cells from rats were purified by Percoll density gradient centrifugation subsequent to enzymatic isolation of testicular interstitial cells. Purified rat Leydig cells (1 x 10(5) cells/ml) were in vitro incubated with human chorionic gonadotropin (hCG, 0.05 IU/ml), forskolin (an adenylyl cyclase activator, 10(-5) M), or 8-bromo-adenosine-3':5'-cyclic monophosphate (8-Br-cAMP, 10(-4) M), SQ22536 (an adenylyl cyclase inhibitor, 10(-6)-10(-5) M), steroidogenic precursors (25-hydroxy-cholesterol, pregnenolone, progesterone, and androstenedione, 10(-5) M each), nifedipine (a L-type Ca(2+) channel blocker, 10(-5)-10(-4) M), or nimodipine (a potent L-type Ca(2+) channel antagonist, 10(-5)-10(-4) M) in the presence or absence of lactate at 34 degrees C for 1 h. The concentration of medium testosterone was measured by radioimmunoassay. Administration of lactate at 5-20 mM dose-dependently increased the basal testosterone production by 63-187% but did not alter forskolin- and 8-Br-cAMP-stimulated testosterone release in rat Leydig cells. Lactate at 10 mM enhanced the stimulation of testosterone production induced by 25-hydroxy-cholesterol in rat Leydig cells but not other steroidogenic precursors. Lactate (10 mM) affected neither 30- nor 60-min expressions of cytochrome P450 side chain cleavage enzyme (P450scc) and steroidogenic acute regulatory (StAR) protein. The lactate-stimulated testosterone production was decreased by administration of nifedipine or nimodipine. These results suggested that the physiological level of lactate stimulated testosterone production in rat Leydig cells through a mechanism involving the increased activities of adenylyl cyclase, cytochrome P450scc, and L-type Ca(2+) channel.
Lin
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Department of Physiology, Schools of Life Science and Medicine, National Yang-Ming University, Taipei 11221, Taiwan, Republic of China.
Wang
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SW
Wang
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RY
Wang
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PS
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002784:Cholesterol / Q000494:pharmacology; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D019344:Lactic Acid / Q000494:pharmacology*; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000032:analysis / Q000096:biosynthesis*; D000098682:Steroidogenic Acute Regulatory Protein
D002121:Calcium Channel Blockers; D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D019344:Lactic Acid; D013739:Testosterone; D002784:Cholesterol; D000242:Cyclic AMP; D002786:Cholesterol Side-Chain Cleavage Enzyme; D009543:Nifedipine