Induction of hepatic metallothionein by feeding zinc to rats of depleted zinc status.
Induction of hepatic metallothionein was investigated in zinc-depleted rats after a single feeding (via stomach tube) of a complete diet with or without supplemental zinc. Subsequent to a maximum elevation in serum zinc (3.25 micrograms/ml) at 3 h, the rate of metallothionein synthesis increased 4.5-fold by 10 h after feeding. Changes in the rate of metallothionein synthesis coincided with similar changes in the level of translatable mRNA coding for metallothionein. Accumulation in liver of Zn2+ as metallothionein rose to a maximum by 12 h after diet administration and thereafter remained constant. Radioactive zinc (65Zn) included in the diet rapidly associated with newly formed metallothionein. Unlike Zn2+, 65Zn exhibited marked fluctuations within the 24-h period following feeding, indicating that zinc associated with metallothionein may be capable of exchange and/or dissociation. Changes in total liver 65Zn were accompanied by concomitant changes in metallothionein-bound 65Zn. This study has related (temporally) the metabolism of dietary zinc to the induction, apparently via transcription of mRNA, of hepatic metallothionein.
D000818:Animals; D004032:Diet; D007408:Intestinal Absorption; D008099:Liver / Q000378:metabolism*; D008297:Male; D008667:Metalloproteins / Q000378:metabolism*; D008668:Metallothionein / Q000096:biosynthesis / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D015032:Zinc / Q000008:administration & dosage / Q000172:deficiency* / Q000378:metabolism*
D008667:Metalloproteins; D012333:RNA, Messenger; D008668:Metallothionein; D015032:Zinc