Abstract

Cortisol and dehydroepiandrosterone (DHEA) are steroids produced by the zona fasciculata (ZF) and reticularis (ZR), respectively, of the adrenal cortex. Both steroids are upregulated in response to adrenocorticotropic hormone (ACTH). Cortisol is a glucorticoid that is important in the regulation of inflammation and metabolism. DHEA is an adrenal androgen important in fetal growth and puberty but tends to decrease gradually after puberty in both men and women. DHEA has various effects on metabolism and immune function including inhibiting the effects of cortisol on some tissues. During the acute phase of stress, cortisol and DHEA rise due to an increase in ACTH released from the anterior pituitary. In contrast, during chronic stress, cortisol remains elevated but DHEA and ACTH levels decrease. Likewise, stress causes serum levels of IL-6 to increase. IL-6 increases cortisol release from the human and bovine adrenal cortex. IL-6 also decreases DHEA release from zona reticularis of the bovine adrenal gland. In humans the effect of IL-6 on DHEA production is still uncertain. To determine a possible mechanism of IL-6 on the zona fasciculata and reticularis, human H294R cells and bovine adrenal tissue were incubated in serum free medium containing IL-6, at various concentrations and incubation intervals. At the end of the incubation interval, mRNA or protein was extracted from the cells or tissue. Standard PCR, real time PCR, and western blot assays were used to determine the effects of IL-6 on the enzymes involved in cortisol and DHEA synthesis, steroidogenic factor-1 (SF-1), steroidogenic acute regulatory protein (StAR), and dosage sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX-1). In human H295R cells and bovine zona fasciculata cells IL-6 caused an increase in SF-1, StAR, P450scc, 17α hydroxylase, 3β-hydroxysteroid dehydrogenase type 2 (3β HSD2), 21 hydroxylase, and 11β hydroxylase mRNA and protein. IL-6 caused DAX-1 mRNA and protein to decrease. These effects were manifest in a time dependent manner. Dose response treatments incubated for 60 min increased SF-1, StAR, P450scc, 17α hydroxylase, 3β HSD2, 21 hydroxylase, and 11β hydroxylase but there was not significant change between the different treatments of IL-6. The bovine zona reticularis stimulated with IL-6 showed a decrease in SF-1, StAR, P450scc, 17α hydroxylase, and 3β HSD2 with an increase in DAX-1 mRNA and protein. This response was manifest in a time dependent manner for both mRNA and protein, and the effect was dose-dependent for mRNA but not protein levels within the 60 min time period. These data provide a mechanism by which increased stress, physical or emotional, which increases IL-6 serum level, could increase cortisol and decrease DHEA. This would account for decreased immune function, increased blood pressure, and changes in metabolism.

Degree

MS

College and Department

Life Sciences; Physiology and Developmental Biology

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2007-07-13

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd1976

Keywords

Adrenal, Cortisol, Dehydroepiandrostendione, interleukin-6, steroidogenesis, zona fasciculata, zona reticularis, Steroidogenic factor-1, DAX-1

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