Peroxidases induced in rat uterus by estrogen administration. II. Cytochemical and biochemical heterogeneity

In estrogen and diethylstilbestrol-treated rats, uterine peroxidases originate from two sources, the infiltrating eosinophils (exogenous) and the uterine tissue itself (endogenous). The study reported here distinguished the exogenous peroxidases by biochemical means and by cytochemistry. Eosinophil peroxidases are confined to the stromal and myometrial regions and appear simultaneously with endogenous peroxidases. At 48 h after estrogen-administration, the clear uterine luminal washings contain five peroxidase isoforms; this increases to 7-15 isozymes by 72 h. Uterine fluid peroxidase isozymes are acidic proteins with pI values ranging from pH 4.0 - 7.2, while the principal eosinophil peroxidase is a basic protein with a pI value ranging from pH 8.0-8.9. Eosinophil peroxidase is electrophoretically demonstrable only in the presence of the cationic detergent cetyltrimethyl ammonium bromide (CTAB) and has a spectrophotometric optimum of pH 4.4. In contrast, uterine fluid peroxidases have a pH optimum of 7.2. and no requirement for CTAB. Uterine tissue peroxidase extracted in the presence of Ca2+, showed a minor electrophoretic peroxidase band in the acidic pH range; however, a CTAB-activated peroxidase similar to the principal eosinophil peroxidase appeared as a basic protein. The data strongly suggest that uterine fluid peroxidases are estrogen-induced peroxidases (EIP) distinct from the eosinophil peroxidases that are largely restricted to the stromal compartment. This conclusion is supported by cytochemical studies that show two eosinophilperoxidases. The one shown by DAB was resistant to cyanide whereas the one shown by PPD/PC was inhibited by cyanide. A uterine tissue peroxidase, which was demonstrated only in stromal cells by the DAB medium, was more sensitive to cyanide than the eosinophil peroxidase shown by DAB.(ABSTRACT TRUNCATED AT 250 WORDS)