Glucocorticoid Metabolites Inhibit the Metabolism of Androstenedione in Red Blood Cells of Ruminants

• Published in: Journal of veterinary medicine. Series A 2003-03, Vol.50 (2), p.98-102
• Main Authors: El-Bahr, S. M., Möstl, E., Palme, R.
• Format: Article
• Language: English
• Subjects: Androstenedione - pharmacokinetics; Animals; Cattle; Chromatography, High Pressure Liquid; Erythrocytes - metabolism; Etiocholanolone - analogs & derivatives; Etiocholanolone - pharmacology; Female; Goats; Male; Sheep
• ISSN: 0931-184X; 1439-0442
• DOI: 10.1046/j.1439-0442.2003.00489.x

Summary The present work aimed to confirm that erythrocytes of ruminants, in general, are capable of converting 17‐oxo to 17‐hydroxysteroids. Special attention was given to 11‐oxoaetiocholanolone (a cortisol metabolite) and its possible interaction with androstenedione as substrates of 17‐hydroxysteroid dehydrogenases (17‐OH SDH). Blood samples were taken from cattle, sheep and goats (n = 3). Aliquots (100 or 300 μl) of washed red blood cell (RBC) suspensions were incubated in triplicates with Ringer's/glucose solution (1 ml) containing either androstenedione (10 ng) or 11‐oxoaetiocholanolone (100 ng) or a mixture of 10 ng of each. Incubations were performed on a shaker at 38°C for 10, 20, 40 or 80 min, respectively. After centrifugation the supernatants were stored at −24°C until analysis. Concentrations of added steroids were measured with enzyme‐immunoassays to monitor their decrease. The 17‐OH SDH activity of RBC was highest in cattle followed by goats and sheep, and 11‐oxoaetiocholanolone was a better substrate than androstenedione. Concentrations of the latter decreased more pronounced, if incubated alone. High performance liquid chromatography separations of the metabolites of 17‐oxosteroids revealed the presence of both, a 17β‐ and 17α‐hydroxylated product formed by erythrocytes of sheep and goats, but only the latter in cattle. The results demonstrated that 11‐oxoaetiocholanolone was also a substrate of RBC 17‐OH SDH and inhibited the metabolism of androstenedione. Therefore, in ruminants, there might be an interaction between cortisol metabolites and gonadal steroids on the level of peripheral steroid metabolism.