Relationship of 65Zn Absorption Kinetics to Intestinal Metallothionein in Rats: Effects of Zinc Depletion and Fasting

Hoadley, James E.; Leinart, A. S.; Cousins, Robert J.

doi:10.1093/jn/118.4.497

Cited by 44 publications

(15 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This was an unexpected finding since it has been shown that, as dietary Zn concentration increases intestinal MT, synthesis is stimulated 3-fold above control levels, 6 h after feeding diets containing up to 25 mg Zn/kg. 33 Thus, it was expected that the induction of MT may have further protected the small intestine from MTX-induced inflammation. 34 The lack of MT induction by high dietary Zn supplementation may have contributed to the lack of efficacy of Zn at preventing MTX-induced gut damage.…”

Section: Zinc Therapy and Methotrexate-induced Mucositismentioning

confidence: 99%

Dietary zinc supplementation and methotrexate-induced small intestinal mucositis in metallothionein-knockout and wild-type mice

Tran¹,

Sundar²,

Howarth³

2009

Cancer Biology & Therapy

View full text Add to dashboard Cite

show abstract

Section: Zinc Therapy and Methotrexate-induced Mucositismentioning

confidence: 99%

Dietary zinc supplementation and methotrexate-induced small intestinal mucositis in metallothionein-knockout and wild-type mice

Tran¹,

Sundar²,

Howarth³

2009

Cancer Biology & Therapy

View full text Add to dashboard Cite

show abstract

“…A role for metallothionein (MT) in cellular zinc uptake and metabolism has been proposed (Shears and Fletcher, 1979, and evidence from mammalian systems suggests that MT functions in nutritive uptake in zinc-deficient animals (Hoadley et al, 1988;Coyle et al, 2000). In addition, glutathione also has an important role in zinc uptake (Jiang et al, 1998), and the presence of zinc bound to low molecular mass ligands following dietary zinc exposure has been noted in freshwater rainbow trout (Spry et al, 1988).…”

Section: Intestinal Zinc Uptakementioning

confidence: 99%

Nutritive metal uptake in teleost fish

Bury

Walker

Glover

2003

Journal of Experimental Biology

424

227

View full text Add to dashboard Cite

Transition metals (i.e. copper, zinc, iron, cobalt, selenium, manganese) are essential for the health of most organisms, forming integral components of proteins involved in all aspects of biological function. Their ubiquity is governed by their ability to form a wide range of coordination geometries and redox states, which allows these elements to interact with many cellular entities, performing pivotal roles in cellular respiration, oxygen transport, protein stability, free radical scavenging, and the action of many cellular enzymes, as well as for DNA transcription. However, in excess they are toxic, binding to inappropriate biologically sensitive molecules or forming dangerous free radicals. Consequently, there is a fine balance between metal deficiency and surplus and it is vital for organisms to maintain metal homeostasis via balancing absorption and excretion.Fish are unique among the vertebrates, a consequence of having two routes of metal acquisition, from the diet and from the water. This review will focus on the uptake processes present in the gill and intestinal epithelium of teleost fish for the three most abundant nutritive metals: iron, copper and zinc. The majority of the available literature concerns metal uptake processes in freshwater teleosts, but where appropriate examples exist, information on seawater teleosts will be reviewed. Molecular evidence indicates that transporters for these metals identified in yeast, plants or mammals all show high sequence homology in key functional regions ), but to date, none of these transporters have been characterised in fish. However, due to the evolutionary conservation of these proteins between yeast, plants and mammals, it is envisaged that fish metal transporters will also belong to the large iron, copper or zinc metal transporter protein families already identified. This review will combine physiological and molecular data to provide an overview of metal uptake mechanisms in teleost fish. IronIron is an essential nutrient to almost all organisms. Iron positioning in the haem moiety of haemoglobin increases oxygen binding and carrying capacity, enabling oxygen transfer to all tissues in multicellular organisms. One of iron's key cellular functions is to confer redox activity to the cytochromes involved in respiration, due to its ability to exchange electrons in aerobic conditions. A negative consequence of iron's redox flexibility is that it produces oxygen free radicals that are toxic to the cell. Consequently, in excess, iron can be detrimental to health. In addition, excess waterborne iron may be toxic to fish, due to the formation of iron 'flocs' on the gills, resulting in gill clogging and respiratory perturbations (Peuranen et al., 1994;Dalzell and MacFarlane, 1999). Teleost fish iron homeostasisThe iron content of fish is, in general, considerably lower than that of other vertebrates (Van Dijk et al., 1975), but the precise daily iron requirements for fish are at present unknown. 11The Journal of Experimental Biology 206, 11-23 © 2003 The Compa...

show abstract

“…It binds zinc on the brush-border surface for its movement through the cell to the basolateral membrane, acting as an intracellular zinc ferry, which is analogous to the action of calbindin-D in intestinal calcium absorption [42]. Thus, dietary zinc absorption is inversely related to the concentration of mucosal MT [41, 43]. In the present study, we found that the CRF rats had a low absorption rate in intestinal zinc absorption and had a higher concentration of mucosal MT as compared with sham-operated rats.…”

Section: Discussionmentioning

confidence: 99%

Intestinal Absorption and Biliary Secretion of Zinc in Rats with Chronic Renal Failure

Chen

Liao²,

Kuo

et al. 2004

Nephron Physiol

View full text Add to dashboard Cite

Background/Aims: In chronic renal failure (CRF), zinc deficiency is partially attributed to decreased intestinal zinc absorption, but the mechanism of this decrease in intestinal zinc absorption is obscure. Therefore, the objective of this study was to investigate the cause of decreased intestinal zinc absorption in a uremic rat model using an in vivo perfusion technique as well as to evaluate the effect of intestinal zinc perfusion on the secretion of biliary zinc in normal and CRF rats. Methods: CRF was induced by five-sixths nephrectomy (Nx). During zinc sulfate perfusion, absorption of zinc in the small intestine and the response of plasma zinc level were measured. After intestinal zinc perfusion for 80 min, the concentrations of zinc and metallothionein (MT) in the intestinal mucosal and liver tissue were assayed. The secretion of biliary zinc and the excretion of urinary zinc were also determined before and after zinc sulfate perfusion. The results were compared with those obtained from 10 sham-operated normal rats. Results: The CRF rats showed a significant decrease in the rate of intestinal zinc absorption and in the response of plasma zinc levels during intestinal zinc perfusion. They also had significantly higher levels of mucosal zinc and MT than sham-operated normal rats, but their contents of liver zinc were significantly lower than those of sham-operated normal rats after zinc sulfate perfusion. CRF rats showed a low plasma zinc level and a high urinary zinc excretion in baseline levels, but had similar output of basal biliary zinc as compared with sham-operated normal rats. Zinc sulfate perfusion in the small intestinal was not found to increase the secretion of biliary zinc and the excretion of urinary zinc, either in normal or CRF rats. Conclusion: In the CRF rat, the reduction of intestinal zinc absorption may result from reduced mucosal zinc efflux from the basolateral membrane into plasma. These data also suggest that the absorbed zinc from the gastrointestinal tract is mostly taken up by the liver or other tissues, and is less excreted in bile juice and urine.

show abstract

Relationship of 65Zn Absorption Kinetics to Intestinal Metallothionein in Rats: Effects of Zinc Depletion and Fasting

Cited by 44 publications

References 17 publications

Dietary zinc supplementation and methotrexate-induced small intestinal mucositis in metallothionein-knockout and wild-type mice

Dietary zinc supplementation and methotrexate-induced small intestinal mucositis in metallothionein-knockout and wild-type mice

Nutritive metal uptake in teleost fish

Intestinal Absorption and Biliary Secretion of Zinc in Rats with Chronic Renal Failure

Contact Info

Product

Resources

About