Increased α1D adrenergic receptor activity and protein expression in the urinary bladder of aged rats
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Abstract
Objectives
A possibility that aging affects (a) expression of the α1D-adrenergic receptor (AR1D), (b) AR1D-mediated contractions and (c) sympathetic innervation in the urinary bladder in rats was studied.
Materials and methods
Contraction produced by phenylephrine and inhibition of these contractions by a non-selective α1-adrenergic antagonist prazosin and a selective AR1D antagonist BMY7378 were compared between 6- and 24-month-old Fisher rats. Expressions of VMAT and AR1D in the bladder were assessed by immunofluorescence and Western blot.
Results
Phenylephrine-induced contractions were larger and inhibition of these contractions by BMY7378 was significantly greater in 24-month-old rats. Aging increased expression of AR1D in the bladder. Density of VMAT-immunoreactive neurites was decreased in smooth muscle but elevated in the suburothelial region of 24-month-old rats.
Conclusions
The results suggest that influence of adrenergic activity on bladder contractility increases with aging is due to overexpression of the AR1D. Influence of adrenergic activity on the urothelial function may also be enhanced with aging.
Keywords
Ovarian hormone depletion Urothelium Suburothelium Sympathetic nerve NoradrenalinNotes
Acknowledgments
Many thanks to Stacy McAllister, Kristina McGinty, Paul Hendrick and Chris Croicu for technical support, and Dr Karen Berkley (R01 NS11892). The research is supported by NIH grants RO3 AG025736 and R01 NS11892
Conflict of interest statement
There is no conflict of interest.
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