Rat β₃-adrenoceptor protein expression: antibody validation and distribution in rat gastrointestinal and urogenital tissues.

β3-Adrenoceptors play important roles in the regulation of urogenital and probably gastrointestinal function. However, despite recent progress, their detection at the protein level has remained difficult due to a lack of sufficiently validated selective antibodies. Therefore, we have explored the selectivity of two antibodies for the detection of rodent β3-adrenoceptors in immunoblots and immunohistochemistry. Of two reportedly promising candidates, antibody AB15688 did not exhibit subtype selectivity in immunoblots. In contrast, the antibody Sc1473 exhibited at least some selectivity in immunoblots and more promising results in immunocytochemical and immunohistochemical stains in cells transfected with cloned β-adrenoceptor subtypes and in rat and mouse tissues. In a systematic screening of rat gastrointestinal and urogenital tissues, Sc1473 produced selective staining in the epithelial cell lining of the stomach and the urothelium of ureter and bladder. We conclude that the two tested antibodies are inappropriate or at least insufficient for immunoblotting applications, but Sc1473 appears to be useful for immunohistochemical detection of β3-adrenoceptor protein in rodent tissues. The β3-adrenoceptor protein exhibits a distinct expression pattern in the rat gastrointestinal and urogenital tract, which is at least partly in line with previously reported functional data.