The urothelium has an important role in sensing and communicating mechanical stimuli, that occur during the stretching of the urinary bladder filling. The key component to this are the mechanoreceptors, including the ion channels Piezo1 and Piezo2. In interstitial cystitis, where the urothelium is changed, the sensing of mechanical stimuli is interrupted. How the changes of the urothelium during cystitis affect the expression of Piezo1 and Piezo2 is not yet known. Cystitis was induced with a single peritoneal cyclophosphamide injection. The presence of Piezo mechanoreceptors in the urinary bladder of rats was checked with western blotting and immunofluorescence. We compared different protocols and antibodies for immunolocalizations of mechanoreceptors Piezo. We used two different antibodies for Piezo1 and an antibody for Piezo2 and different secondary antibodies. The presence of Piezo1 was demonstrated by a single antibody while western blotting of Piezo2 did not show marks on the correct size. On cryosections with immunofluorescence, Piezo1 showed a stronger reaction in samples injected with cyclophosphamide in comparison to sections of untreated rats. The reaction was mainly present on the apical plasmalemma of umbrella cells and also on basal and intermediate cells. In Piezo2 the reaction was weaker but was also seen in all three urothelium layers, the lamina propria, and the detrusor. With both Piezo mechanoreceptors a reaction was visible on the top and body of the urinary bladder and there were no differences between these two regions. The reaction was weaker in Piezo1 or non-existent in the case of Piezo2 in the basal region. With immunofluorescence we thus demonstrated a stronger reaction of Piezo protein in the urothelium after being injected with cyclophosphamide and showed their presence in all layers of the urothelium. We evaluated new protocols of sample preparation, thus enabling new studies of urinary bladder of rats and setting the stage for further studies of determining the role of Piezo mechanoreceptors during cystitis.
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