Induction of lauric acid hydroxylase activity in catfish and bluegill by peroxisome proliferating agents

In mammals, sensitivity to peroxisome proliferation by peroxisome prolifera ting agents (PPAs) appears to be correlated with inducibility of lauric aci d hydroxylase activity. Bluegill and catfish have been shown to respond to PPAs by induction of lauric acid hydroxylase immunoreactive proteins (Haasc h, 1996). In this investigation, induction of lauric acid hydroxylase activ ity was confirmed by HPLC and mass spectral analysis of specific hydroxylat ion products and possible species-specific differences in metabolism were i nvestigated. Male bluegill, channel catfish and rat, were administered the model PPAs, clofibrate (200 mg kg(-1), i.p.), ciprofibrate (100 mg kg(-1), i.p.), or olive oil as vehicle control (both sexes of catfish), 48 h prior to hepatic, trunk kidney (catfish only) or kidney (rat) microsome preparati on. In general, total metabolism of lauric acid was similar in all species, but female catfish metabolize lauric acid to a greater extent than males. Ciprofibrate treatment produced significant induction of omega-and omega-6 hydroxylation in male catfish kidney. In male bluegill liver, omega-, omega -4 and omega-5 hydroxylations were significantly induced by clofibrate trea tment. The data indicate that induction of lauric acid hydroxylase cytochro me(s) P450 occurs in PPA-exposed fish which may be a consideration for envi ronmentally-exposed responsive species. (C) 1998 Elsevier Science Inc. All rights reserved.