An immunohistochemical study on the localization and distribution of epoxide hydrolase within livers of untreated rats

Antiserum produced against epoxide hydrolase (EC 3.32.3) which had been purified to apparent homogeneity from rat hepatic microsomes was employed in unlabeled antibody peroxidase-antiperoxidase and indirect fluorescent antibody staining techniques to inves-tigate the localization and distribution of the enzyme within livers of untreated rats. Using both immunohistochemical procedures, staining for epoxide hydrolase was detected within hepatocytes throughout the liver. However, differences were noted in the intensity of immunohistochemical staining of hepatocytes within the liver lobule. Microfluoro-metric determinations of the relative extents of binding of the anti-epoxide hydrolase to hepatocytes within the three regions of the liver lobule revealed that, although midzonal and periportal hepatocytes bound the antibody to similar extents, centrilobular hepato-cytes bound significantly more anti-epoxide hydrolase. Similar patterns of intralobular distribution for the anti-epoxide hydrolase were determined within livers of untreated male and female rats. Furthermore, similar intralobular patterns of immunohistochemical staining were observed within the right, median, left, and caudate lobes of the liver