Water sparing in chronic ethanol exposure is associated with elevated renal estrogen receptor beta and vasopressin V2 receptor mRNA in the female rat

Huckstep, Odaro J.
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Fluid handling is known to differ between males and females. Interactions between sex steroids such as estrogen with fluid regulating hormones like vasopressin (VP) are likely key to establishing these differences. Research has identified estrogen receptor (ER) α and β in renal tissue which may affect renal fluid handling. Thus, this study hypothesized that chronic ethanol exposure would elicit different alterations to water load excretion between male and female Sprague Dawley (SD) rats due to changes in renal VP V2 receptor (V2R) or ER mRNA expression. Therefore, in this study we compared 120 minute excretion of a 2% Body Weight (BW) water load between male control (n=6) and ethanol-fed (n=14) rats, and female control (n=26) and ethanol-fed (n=26) rats. Additionally renal papilla mRNA expression of V2R, ERα, and ERβ was compared between male control (n=5) and ethanol-fed (n=15) rats, and female control (n=12) and ethanol-fed (n=17) rats. Female ethanol fed rats showed a 16% reduction in water load excretion (p<0.05) compared to controls. RT-PCR analysis revealed that the decreased water excretion in ethanol-fed females was accompanied by a 40% increase in V2R mRNA (p<0.05) and a 146% increase in ERβ mRNA (p<0.05) in renal papilla tissue compared to controls. In contrast, ethanol treatment in male rats resulted in no difference in water excretion, and yielded no change to V2R or ERβ mRNA expression in the renal papilla. ERα expression was not different between males and females, nor affected by ethanol treatment. Overall, these results suggest that females can better compensate for the dehydrating effects of ethanol exposure by increasing renal responsiveness to VP via upregulating renal V2R. Also, ethanol specifically upregulates the ERβ subtype in the female kidney which may modulate renaI sensitivity to VP.
Thesis (M.S.)--University of Hawaii at Manoa, 2007.
Includes bibliographical references (leaves 29-31).
v, 31 leaves, bound 29 cm
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