title: Effect of dietary retinoic acid on circulatory vitamin A homeostasis in polybrominated biphenyl-treated rats.
abstract: Retinoic acid (RA) supplementation is known to lower the amount of retinol in circulation. In contrast, the feeding of polyhalogenated aromatic hydrocarbons results in an elevated level of circulatory retinol. We investigated the effect of short-term dietary exposure to RA on the amount of serum retinol in female Sprague-Dawley rats fed either a basal diet (control rats) or the basal diet containing 100 mg of polybrominated biphenyls (PBBs)/kg diet (PBB-treated rats). After feeding of the above diets for 137 d, RA (12 mg/kg diet) was included in both the control and PBB-containing diets. The rats were fed the RA-containing diet for 3 d and then killed (d 140). Blood samples were obtained before and after RA treatment. Chronic PBB treatment of rats resulted in lower hepatic vitamin A and higher kidney vitamin A than in control rats. Serum retinol concentration was significantly higher in rats treated with PBB for 137 d than in controls; the subsequent treatment with RA lowered serum retinol to a level that was not different from that of control rats treated with RA. Our observations agree with earlier findings that 1) PBB treatment alters vitamin A homeostasis, and 2) dietary RA lowers the amount of circulatory retinol. An important new observation is that serum retinol homeostasis in PBB-treated rats appears to be regulated by a mechanism similar to that of normal rats. Polyhalogenated aromatic hydrocarbons may thus be useful tools to study the control mechanisms of vitamin A homeostasis.
authors.affiliation: Department of Pathology, Michigan State University, East Lansing 48824.
authors.forename: R K
authors.initials: RK
authors.lastname: Jensen
authors.forename: M H
authors.initials: MH
authors.lastname: Zile
mesh_terms: D000818:Animals; D004032:Diet; D005260:Female; D006706:Homeostasis / Q000187:drug effects*; D007668:Kidney / Q000032:analysis; D008099:Liver / Q000032:analysis; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D014212:Tretinoin / Q000494:pharmacology*; D014801:Vitamin A / Q000032:analysis / Q000097:blood*
chemical_list: D011075:Polybrominated Biphenyls; D014801:Vitamin A; D014212:Tretinoin