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Title: Steroid secretory profile and steroidogenic acute regulatory (StAR) mRNA expression in cultured bovine adrenocortical cells
Author: Nicol, Moira Ruth
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2002
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ACTH is the principal factor stimulating the formation and release of cortisol from the adrenal cortex and is controlled, in part, by the negative feedback inhibition of cortisol. Investigation into the kinetics of cortisol production by cultured bovine adrenocortical cells in response to ACTH-treatment and the relationship between the cortisol secretion and the expression of the steroidogenic acute regulatory (StAR) mRNA was undertaken. ACTH (10nM) treatment of BAC cells on day 3 of culture displayed an increase in the rate of cortisol output over the initial 6 hours, P<0.05 at each time point compared with untreated cells, followed by a marked decline in the secretion rate thereafter. The decline in the cortisol secretion rate was not due to a decrease in the number of cells as the protein content of the culture wells did not vary by ore than 10% over the 12 hour period. Nor was the decrease in cortisol secretion a result of serum-deprived culture as a comparable response was seen in serum-replete conditions. HPLC analysis of the culture medium revealed the secretion of four main steroids; cortisol, corticosterone, cortisone and 11β-hydroxyandrostenedione. Cortisol was found to account for ~ 50% of the total steroid output by BAC cells at each of the time points studied. The total steroid output increased over the initial 6 hours (6.1nmol/106 cells at 6 hours) followed by a decline in levels to 4.4nmol/106 cells at 12 hours. Thus, the decline in cortisol secretion was not due to the production of another steroid in preference to cortisol. Various concentrations of ACTH also invoked a similar pattern of cortisol secretion as did treatment of BAC cells with angiotensin II. Interestingly, no decline in cortisol secretion was found when BAC cells were treated with forskolin or 8Br-cAMP. Receptor desensitisation was ruled out as the cells responded to a second ACTH-treatment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available