Dietary soy isoflavone replacement improves detrusor overactivity of ovariectomized rats with altered connexin-43 expression in the urinary bladder

Abstract

To evaluate the effects of dietary soy isoflavone on detrusor overactivity (DO) in ovariectomized (Ovx) rats and the association between these effects and expression of the gap junction protein, connexin-43, in the urinary bladder, and to discuss the usefulness of soy isoflavones for overactive bladder (OAB).

Materials and methods: In all, 24 (8-week-old) virgin female Sprague-Dawley rats were divided equally into four groups: sham operation with control diet (with no dietary soy isoflavones; Sham-CD), bilateral Ovx with CD (Ovx-CD), sham operation with soy isoflavone diet (Sham-ID), bilateral Ovx with soy ID (Ovx-ID). Cystometry was performed after the 4-week CD or ID in each group while awake. Quantitative reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemical and Western blot analyses were also performed to examine the expression of connexin-43 in each group.

Results: In Ovx-CD rats, there were some significant changes in cystometry variables, including shortening of the intercontraction interval and an increased number of non-voiding contractions compared with Sham-CD rats (P < 0.05). These changes were significantly improved by 4-week soy isoflavone administration (Ovx-ID; P < 0.05). Quantitative RT-PCR, immunohistochemical and Western blot analyses showed that the expression level of connexin-43 mRNA and protein was significantly greater in the urinary bladder of Ovx-CD rats compared with Sham-CD rats. Soy isoflavone administration significantly reduced this increased expression (Ovx-ID).

Conclusions: Soy isoflavone replacement improved DO with alteration of the connexin-43 expression pattern in the urinary bladder of Ovx rats. Routine consumption of diet soy isoflavones may be a useful treatment to prevent and improve OAB.