Distribution and inducibility of P-glycoprotein in the catfish: immunohistochemical detection using the mammalian C-219 monoclonal

Mounting evidence suggests that the P-glycoprotein (pgp) efflux pump may be a modulator of bioavailability and a mode of excretion for xenobiotics. Im munohistochemistry was utilized to examine the distribution and inducibilit y of a pgp like protein in catfish. Immunoreactivity to the MDR C-219 monoc lonal antibody was noted primarily in bile canaliculi or bile preductules o f the liver, discrete areas of the extratubular region of the kidney and th e columnar epithelia of the intestine. Regional differences in pgp content were noted in the intestine with the distal region containing greater pgp l evels than the proximal intestine. Dietary administration of vincristine, a prototypic pgp inducer and beta -naphthoflavone an Ah agonist resulted in induction of the C-219 immunoreactivity in the liver and the distal intesti ne. These results are consistent in location and inducibility with pgp like proteins and support a possible relationship to xenobiotic absorption and/ or excretion in the catfish. (C) 2000 Elsevier Science Ltd. All rights rese rved.