Leslie M. Rickey, Sara L. Sarkey, Lydia L. DonCarlos

Loyola University Medical Center, Maywood, IL

Introduction: Urinary incontinence affects approximately 1/3 of post-menopausal women. Circulating estrogen levels fall at menopause, but there is conflicting evidence whether voiding symptoms in these women are related to hypoestrogenism or aging itself. Although the innervation of the lower urinary tract and the spinal pathways to the pontine micturition center (PMC) in the brainstem are fairly well understood, the exact mechanisms by which higher brain centers modulate voluntary control of the micturition reflex have yet to be elucidated. The medial preoptic area (MPA) is a forebrain structure that has been identified by neuroanatomical and functional studies to be involved in micturition.

Objective: This neuroanatomical study was designed to determine whether specific central nervous system (CNS) pathways that project to the PMC (also known as “Barrington’s nucleus”) are estrogen sensitive in a rat model.

Methods: Using adult female Sprague-Dawley rats, stereotaxic procedures were used to accurately localize the PMC, using coordinates based on landmarks on the skull. A fluorescent retrograde neuroanatomical tracer was injected into the PMC to identify neurons in the MPA that project to the PMC. Immunohistochemistry was performed using antibodies directed against estrogen receptor-alpha (ERα) and estrogen receptor-beta (ERβ) to identify estrogen-sensitive neurons. The brain sections were examined using fluorescence microscopy to identify cells that project to the PMC (contain fluorescent tracer) and also express ER (are immunoreactive for ER).

Results: There are neurons in the MPA that are double labeled (contain fluorescent tracer and express ERα, but not ERβ), showing that subsets of neurons projecting from the MPA to the PMC are estrogen-sensitive.

UroToday.com Coverage of SUFU 2007

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