TRANSFER OF DEUTERIUM FROM [1,1-H-2(2)]ETHANOL TO STEROIDS AND ORGANIC-ACIDS IN THE RAT TESTIS

Rats were given [1,1-H-2(2)]ethanol in a single dose, and the H-2 content was determined in testicular steroids and in organic acids of low molecular mass in the testis, liver and blood. The acids were quantified by capillary gas chromatography/mass spectrometry of t-butyldimethylsilyl derivatives with [H-2(4)]lactate as internal standard. In addition to lactate, pyruvate, 3-hydroxybutyrate and acids of the tricarboxylic acid cycle, the testis was shown to contain 2-hydroxybutyrate, 2-hydroxy-2-methylbutyrate, 2-hydroxyisohexanoate and glycerate. No H-2 was found in pregnenolone, 5-androstcne-3-beta,17-beta-diol or testosterone, whereas the abundance of monodeuterated molecules of 5-alpha-androstane-3-alpha,17-beta-diol and its 3-beta-isomer were 7.6 % and 11.2 % respectively. The abundance of monodeuterated lactate was 7.0 % in the testis and 5.3 % in the blood. The other acids were less labelled but 3-hydroxybutyrate had a higher H-2 content in the testis (3.1 %) than in the liver. These results support the contention that ethanol is oxidized in an alcohol dehydrogenase-catalysed reaction in testis in vivo and that the acute inhibition of the testosterone production is due at least partly to a redox effect. The labelling and increased concentration of 3-hydroxybutyrate in the testis indicate that a change in the mitochondrial redox state might be involved.