Intestinal metallothionein gene expression and zinc absorption in rats are zinc-responsive but refractory to dexamethasone and interleukin 1 alpha.
The effects of dexamethasone and interleukin 1 alpha on intestinal metallothionein gene expression and zinc absorption were studied. Rats given parenteral zinc served as positive controls. A single intraperitoneal or intravenous dose of dexamethasone, interleukin 1 alpha or zinc markedly increased liver metallothionein synthesis 3-9 h after injection. Intestinal metallothionein mRNA and metallothionein protein were not affected by dexamethasone or interleukin 1 alpha, but were markedly increased by parenteral zinc. Absorption of 65Zn from isolated duodenal segments was inversely related to intestinal metallothionein concentration in rats given zinc, but was not affected by dexamethasone or interleukin 1 alpha. Plasma zinc concentrations decreased in rats given dexamethasone or interleukin 1 alpha and increased in those given zinc, but they were not related to 65Zn absorption. Similarly, multiple intraperitoneal administration of either dexamethasone or interleukin 1 alpha, or oral administration of dexamethasone, for 7 d markedly increased liver metallothionein synthesis but did not affect intestinal metallothionein concentration or 65Zn absorption. These results suggest that intestinal metallothionein gene expression and 65Zn absorption are refractory to glucocorticoid hormone and interleukin 1 alpha.
Hempe
J M
JM
Food Science and Human Nutrition Department, University of Florida, Gainesville 32611.
Carlson
J M
JM
Cousins
R J
RJ
D000818:Animals; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D007375:Interleukin-1 / Q000008:administration & dosage / Q000494:pharmacology*; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis*; D051381:Rats; D014018:Tissue Distribution; D015032:Zinc / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*
D007375:Interleukin-1; D003907:Dexamethasone; D008668:Metallothionein; D015032:Zinc