The long term goal of this research is to elucidate the mechanisms by which the adrenal steroid dehydroepiandrosterone (DHEA) mediates its pleitropic effects in extrahepatic tissues. DHEA treatment is purported to have numerous beneficial effects in humans, such as lowering risk of cardiovascular disease and lowering body fat. In rodents, low doses of DHEA are chemopreventive, whereas high doses of DHEA lead to peroxisome proliferation and eventually hepatocarcinogenesis. The effects of DHEA are thought to be related to its ability to modulate gene expression. High doses of DHEA increase expression of several hepatic genes including those of the cytochrome P450 monooxygenase 2C and 4A families. The effects of DHEA on expression of these genes in the kidney is not known. Since renal cytochrome P450 monooxygenases of the 4A and 2C families are important in metabolism of arachidonic acid to various vasoactive eicosanoids, modulation of P450s by DHEA may affect basic renal physiological processes, such as maintenance of blood pressure.
The specific aims of the research proposed here are to l) assess the effects of low and high doses of DHEA on renal gene expression, 2) assess the effects of DHEA treatment in a salt-sensitive rat model for hypertension, and 3) assess the effects of low and high doses of DHEA on hepatic and renal expression of a broad range of genes using cDNA array technology. Completion of these aims will help determine how DHEA mediates its pleiotropic effects and allow better determination of benefits and risks of DHEA treatment in humans.
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