Comparison of three histological fixatives on the immunoreactivity of mammalian P-glycoprotein antibodies in the sheepshead minnow,Cyprinodon variegatus

Abstract

Mammalian P-glycoprotein is a highly conserved integral membrane protein functioning as an energy-dependent efflux pump which decreases the concentration of certain lipophilic aromatic compounds entering the cell by diffusion. Expression of such a transporter in teleost species could play a significant role in conferring resistance to fish populations exposed to xenobiotic stressors and may serve as a potential indicator of species at risk for certain environmental contaminants. In previous studies we demonstrated that a strong correlation existed between corresponding mammalian and teleost tissues showing immunoreactivity to specific mammalian P-glycoprotein antibodies. In the present study, comparisons of staining pattern, intensity, and tissue specificity between tissues treated in Bouin's, Dietrich's and Lillie's histological fixatives were determined in the sheepshead minnow, Cyprinodon variegatus, using monoclonal antibodies C219, C494, JSB-1 and polyclonal antiserum MDR(Ab-1). Immunoreactivity of these antibodies was found to be fixative-dependent. Results are presented illustrating the differential staining patterns and tissue specificity observed for each tissue type, fixative, and antibody combination. Our data indicate tissue fixation has a significant impact on P-glycoprotein antibody immuno-reactivity in teleost tissues and must be considered in the comparison and interpretation of results.