Changes in awake cystometry and expression of bladder β-adrenoceptors after partial bladder outlet obstruction in male rats

Abstract

Purpose: To explore possible changes in awake cystometry and expression of beta-adrenoceptors (ARs) as a cause for bladder dysfunction in a male rat model of partial bladder outlet obstruction (pBOO). Materials and Methods: Awake cystometry was performed in rats with pBOO (16) and sham-operated rats (16), 8 weeks after the operation. The expression of mRNA and protein of β-ARs was assessed by real-time PCR and western blot. Results: The bladders with pBOO (1030mg) were increased compared to those in control rats (230mg). In the cystometric studies, the maximum intravesical pressure significantly increased in the pBOO group compared to control group rats (p=0.001). The time to reach maximal intravesical pressure during micturition in the pBOO group was significantly longer than the sham group (p=0.003). The frequency of non-void contraction in the pBOO group was significantly more than the sham group (p=0.006). The mRNA expressions of β2- and 3-ARs were increased insignificantly in pBOO group compared to sham group. The data of pBOO group expressed as folds of corresponding expression in sham group were 1.28 and 1.46 respectively in β2- and 3-ARs. Compared to the sham groups, the density of 60Kda protein band recognized by β2-AR antibodies and the density of 45Kda protein band recognized by β3-AR antibodies were higher in the bladder from pBOO group rats. Conclusion: PBOO of male rats increase the maximal intravesical pressure and contraction time during micturition and the frequency of non-void contraction as well as weight of bladder. The expression of β2-and 3-ARs subtypes was increased insignificantly compared to sham operated group. This study demonstrates that the changes of cystometric or non-void contraction parameters in pBOO is one of the pathophysiologic processes potentially associated with the alterations of bladder β-ARs.