Exploring the Glucocorticoid Actions of 1α-Hydroxycorticosterone (1α-OH-B) in the Elasmobranch Fishes

<p>The corticosteroid 1α-hydroxycorticosterone (1α-OH-B) is unique to the elasmobranch fishes. It is thought that 1α-OH-B acts as both the primary glucocorticoid (GC) and mineralocorticoid (MC) in these fishes, a dual role analogous to that of cortisol in the teleost fishes. The MC characteristics of 1α-OH-B are well supported, but data supporting its GC functions are lacking. In this study, the putative GC actions of 1α-OH-B were examined. The first experiment characterized the physiological stress response of the Atlantic stingray (<em>Dasyatis sabina</em>) to air exposure, with particular regards to the roles of corticosteroids and metabolic fuels. Results demonstrate that corticosteroids increase in a corresponding manner to glucose, supporting a GC role for 1α-OH-B. Also, to determine the ability of 1α-OH-B to regulate the transcription of genes classically regulated by GCs, I isolated and sequenced the mRNA encoding serum- and glucocorticoid- inducible kinase 1 (SGK1). <em>SGK1 </em>mRNA abundance was upregulated in red blood cells incubated with 1α-OH-B. The results of these studies support the putative GC actions of 1α-OH-B, including the correlation of 1α-OH-B with basal glucose <em>in vivo </em>and the first report of direct mRNA regulation by this unique corticosteroid. Future studies should focus on the characterization of transcriptional regulation by 1α-OH-B, including the identification of GC response elements in the promoter of <em>SGK1 </em>and other genes, and also the development of a specific antibody for the quantification of 1α-OH-B.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Discipline thesis:degree_discipline

Coastal Sciences, Gulf Coast Research Laboratory

Year dc:date.available

2014

Author dc:creator

• Lambert, Faith Nichole

Contributors dc:contributor

• Andrew Evans
• Joe Griffitt
• Jodie Jawor

• SGK
• 1α-OH-B
• Atlantic stingray
• stress response
• corticosteroids
• elasmobranch
• Cellular and Molecular Physiology
• Endocrinology

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/68

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1066