Enhanced Hypoxia-Associated Genes in Impaired Contractility From Bladder Outlet Obstruction

Abstract

BACKGROUND: Hypoxia damages the bladder wall and contributes to the initiation of bladder dysfunction. The change of hypoxia is not well known in impaired bladder contractility caused by long-term bladder outlet obstruction (BOO). We aimed to find out whether hypoxia of bladder tissue is present and what signaling mechanisms are involved in the decompensated bladder in BOO. METHODS: Twenty 6-week-old female Sprague-Dawley rats were divided into 2 groups, 10 rats each: group 1, sham operation; group 2, BOO for 8 weeks. Eight weeks after the onset of BOO, we did cystometric evaluation and processed polymerase chain reaction (PCR) array for hypoxia pathway using bladder tissues. The PCR array consists of 84 genes known to be involved in the hypoxic response, cell differentiation, and metabolism. We did quantitative PCR (qPCR) and immunohistochemical staining of bladder tissue for hypoxia. RESULTS: Eight genes were at least 2-fold upregulated and 3 genes were at least 2-fold downregulated in BOO group, compared with the sham operation group. The up-regulated genes (fold change) belonging to the hypoxia-inducible factor (HIF) 1 interactor included Cdkn2a (11.0), and the down-regulated genes belonging to HIF and co-transcription factors included Hif3a (-39.6) and Per1 (-5.1) by BOO. Genes influenced each other by means of TGFβ1, TNF, and TP53. CONCLUSION: Hypoxia genes were increased in impaired contractility because of long-term BOO. The gene expression profiles could explain the molecular mechanisms of hypoxia in impaired contractility because of long-term BOO.