In vitro Metabolic Changes in the Corticosteroidal Hormones in Faeces

Objective: The present study aimed to investigate the extent of stability of corticosteroid hormones against the bacterial actions and their enzymatic activities that are naturally occurring in faeces. Materials and Methods: Faecal samples were freshly collected from each of 10 cattle and 10 sheep. Each sample was immediately incubated in a water bath at 38°C with either 1 μg of cortisol or corticosterone. The incubations were then run at time interval of 4, 8 and 24 h (in cattle) and at 1, 2, 4, 8 and 24 h (in sheep). The samples were extracted with methanol and the aliquots were taken after centrifugation from their supernatants and analyzed for measurement of cortisol and corticosterone by Enzyme Immunoassays (EIAs). Results: A dramatically decline in the concentrations of the added cortisol and corticosterone was observed in cattle faeces. Only about 20% of the starting levels of both hormones after 4 h in contrast to almost no cortisol with about 10% of corticosterone after 8 h and about 5% of corticosterone after 24 h was detected. Prolonged incubation of faecal samples of sheep decreased the immunoreactive substances measured by the 3-hydroxy, 11-oxoandrogens EIA (11-oxo-A-EIA), whereas with the 11, 17 dioxoandrostanes EIA (11, 17 DOA-EIA), the values were increased. Conclusion: Cortisol was heavily metabolized by faecal flora being quicker in its metabolism than corticosterone in the faeces of ruminants. In addition, the present study provides a powerful evidence to the absence of native cortisol in the faeces of ruminants.