- Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences
Larsson, Pia; Tjälve, Hans
Whole-body autoradiography of H-3-labeled aflatoxin B-1 in young pigs shoved a localization of bound label in the nasal olfactory and respiratory mucosa, in the tracheo-laryngeal mucosa, and in the conjunctiva, in addition to the liver. Whole-body and microautoradiography also showed a labeling of pigmented tissues, which can be ascribed to a melanin binding of AFB(1), In vitro experiments with microsomal preparations of various tissues from sows revealed that the nasal respiratory and olfactory mucosa had the highest capacity to form DNA-bound aflatoxin B-1-metabolites. The tracheal mucosa and the liver, in order, had lesser binding capacity. The lung was found to be devoid of aflatoxin B-1-bioactivating capacity. In vitro microautoradiography revealed bound label in specific cell types in; the nose and trachea and in some cells of the conjunctiva. A drastic decrease in the aflatoxin B-1-DNA binding was observed when microsomal preparations of the nasal respiratory and olfactory mucosa were incubated in the presence of reduced glutathione, but without any addition of cytosolic glutathione-S-transferases. In incubations of liver microsomes under these conditions a somewhat lower inhibition of the aflatoxin B-1-DNA binding was seen. Our results demonstrate that the nasal olfactory and respiratory mucosa and the tracheal mucosa have a higher capacity than the liver to bioactivate aflatoxin B-1 in swine. Our data further show that microsomal-associated glutathione-S-transferases with a high capacity to catalyze the conjugation of the reactive aflatoxin B-1-epoxide to reduced glutathione are present in the nasal olfactory and respiratory mucosa of swine.
aflatoxins; pigs; conjunctiva; melanins; glutathione transferase
Journal of Animal Science
1996, Volume: 74, number: 7, pages: 1672-1680
Publisher: AMER SOC ANIMAL SCIENCE