Simultaneous immunostaining method for localization of bromodeoxyuridine and calcitonin gene-related peptide

A new simultaneous double immunostaining method has been optimized to localize the DNA synthesis marker bromodeoxyuridine (BrdU) and calcitonin gene-related peptide (CGRP) in endocrine cells of Bouin's-fixed, paraffin-embedded rat lung. Nuclease pre-treatment before immunostaining is compatible with optimal tissue morphology and CGRP antigenicity preservation. Nickel-enhanced development of avidin-biotin-peroxidase staining is used to show CGRP immunoreactivity in black and alkaline phosphatase-anti-alkaline phosphatase is applied to demonstrate incorporated BrdU in red. The present methodology could be useful for studies requiring detection of incorporated BrdU in cells producing regulatory peptides or other labile antigens.