Introduction Stereospecific hydroxylation of testosterone has been related to the activity of specific isoforms of P450 (1) and, in cattle, CYP3A has been reported to be involved in the production of 2beta-hydroxytestosterone (2beta-OHT), 6beta hydroxytestosterone (6beta-OHT) and androstenedione (2,3). The aim of this study was to evaluate the pattern of hydroxylation of testosterone in calves treated with hormones at dosages schedules usually adopted in illegal treatment. Material and methods Calves were randomly organised in 6 groups as follow, control (C), and treated with estradiol (E, 25 mg), testosterone (T, 100 mg), nortestosterone (NT, 100 mg), E+T (25 mg + 100 mg), E+NT (25 mg + 100 mg). Single or combined hormones im administrations were at day 0 and after 14, 28 and 42 days. All the animals were slaughtered 14 days after the last treatment (day 58) and liver lobes collected for microsome preparations. Microsomes (0.2 mg/ml) were incubated for 10 min, at 37°C with 250 µM TST. Metabolites were extracted with methylene chloride and hydroxy-TST metabolites (OHT) were separated according to Purdon (1) with a Jasco HPLC using a C18column and ternary (water, acetonitrile, methanol) gradient elution. Elution times were compared with those of pure standards (Steraloids). Conclusions Liver microsomes from NT treated calves produced significantly (*P<0.001) lower amount of 6beta-OHT, 16beta-OHT, and 2beta-OHT, and detectable quantities of two other metabolites: 11alfa-OHT and 7alfa-OHT, never found in the incubation extracts obtained with the other groups of treatment. The lacking of significant effects on OHT metabolites production in animal treated with E, T, E+NT and E+T it is likely due to the too long interval time (14 days) between the last hormone administration and the animal slaughtering. Nevertheless at that time the inhibitory effect related to the NT treatment was still evident.

In vivo hormone treatments in calves: effects on in vitro hydroxylation of testosterone

CAPOLONGO, FRANCESCA;MERLANTI, ROBERTA;DE LIGUORO, MARCO;MONTESISSA, CLARA
2003

Abstract

Introduction Stereospecific hydroxylation of testosterone has been related to the activity of specific isoforms of P450 (1) and, in cattle, CYP3A has been reported to be involved in the production of 2beta-hydroxytestosterone (2beta-OHT), 6beta hydroxytestosterone (6beta-OHT) and androstenedione (2,3). The aim of this study was to evaluate the pattern of hydroxylation of testosterone in calves treated with hormones at dosages schedules usually adopted in illegal treatment. Material and methods Calves were randomly organised in 6 groups as follow, control (C), and treated with estradiol (E, 25 mg), testosterone (T, 100 mg), nortestosterone (NT, 100 mg), E+T (25 mg + 100 mg), E+NT (25 mg + 100 mg). Single or combined hormones im administrations were at day 0 and after 14, 28 and 42 days. All the animals were slaughtered 14 days after the last treatment (day 58) and liver lobes collected for microsome preparations. Microsomes (0.2 mg/ml) were incubated for 10 min, at 37°C with 250 µM TST. Metabolites were extracted with methylene chloride and hydroxy-TST metabolites (OHT) were separated according to Purdon (1) with a Jasco HPLC using a C18column and ternary (water, acetonitrile, methanol) gradient elution. Elution times were compared with those of pure standards (Steraloids). Conclusions Liver microsomes from NT treated calves produced significantly (*P<0.001) lower amount of 6beta-OHT, 16beta-OHT, and 2beta-OHT, and detectable quantities of two other metabolites: 11alfa-OHT and 7alfa-OHT, never found in the incubation extracts obtained with the other groups of treatment. The lacking of significant effects on OHT metabolites production in animal treated with E, T, E+NT and E+T it is likely due to the too long interval time (14 days) between the last hormone administration and the animal slaughtering. Nevertheless at that time the inhibitory effect related to the NT treatment was still evident.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2457156
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