Zinc selenite

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Effects of Chemical Form and Dosage on the Incorporation of Selenium into Tissue Proteins in Rats

Author:

Behne, Dietrich, et al.

Year:

1991

Bibliographic source:

American Institute of Nutrition

Materials and methods

Objective of study:

toxicokinetics

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Selenium

EC Number:

231-957-4

EC Name:

Selenium

Cas Number:

7782-49-2

Molecular formula:

Se

IUPAC Name:

selenium

Constituent 2

Reference substance name:

ambient Se

IUPAC Name:

ambient Se

Details on test material:

Elemental selenium measured, source unknown.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

Extremely Se-depleted male Wistar rats (Mus Rattus, Brunnthal, Germany) that were fed a diet with a Se content of only 2 ug/kg for six generations were used for the study

Applicant's summary and conclusion

Conclusions:

This study was used to support the hypothesis that internal concentration levels are generally higher for doses delivered as an organic form of selenium (e.g. selenomethionine) than for the same dose delivered as an inorganic form.

Executive summary:

The publication investigated the incorporation of Se into the proteins of liver and muscle, the two main Se pools, during replenishment of Se-deficient rats with normal or large doses of 75Se-labeled selenite and selenomethionine, doses equivalent to the amounts ingested from a diet with 0.2 or 2 mg Se/kg. With the higher intake, Se levels were elevated. More Se was retained from selenomethionine than from selenite. After separation of the labeled proteins, it was apparent that the higher tissue Se contents were mainly due to nonspecific incorporation into a large number of proteins. The autors observed no differences between the two chemical forms with regard to the formation of the specific selenoproteins. The 10-fold increase in the Se supply led to a relatively small rise in the levels of these com pounds. The results indicate that after ingestion of normal amounts of selenite nearly all of the element is present in the specific selenoproteins. With increasing doses a part is also incorporated nonspecificalry into numerous other proteins. In the case of selenomethio nine, a part of the element follows the same metabolic pathways, but a percentage is also deposited directly and nonspecificalry into proteins in place of methionine.