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The pathogenesis and prevention of chronic copper, heliotrope and hepatogenous chronic copper poisoning in sheep

Noordin, Mohamed-Mustapha (1992) The pathogenesis and prevention of chronic copper, heliotrope and hepatogenous chronic copper poisoning in sheep. PhD thesis, Murdoch University.

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Abstract

This thesis describes a study undertaken to determine the efficacy and mechanism of zinc (Zn) administration in alleviating clinical signs, tissue damage and copper (Cu) accumulation in sheep fed excessive Cu and the plant Heliotropium europaeum (heliotrope) separately or in combination.

Copper and Zn were given orally in gelatine capsules on 5 days of the week. Sheep were maintained on either a diet containing a low concentration of Cu or the same diet to which heliotrope had been added to give a pyrrolizidine alkaloid content of 0.13%. Animals were observed for clinical signs of jaundice and haemoglobinuria. Tissues were collected by biopsy or after death for biochemical and morphological studies.

Sheep fed Cu and heliotrope separately developed changes in the liver which were typical of their respective treatments, but when Cu and heliotrope were fed in combination, much more severe clinical signs and pathological changes developed. Copper accumulation occurred in all sheep receiving Cu supplementation, however this was greater in those sheep given Cu and heliotrope together. Tissues of sheep fed heliotrope alone or in combination with Cu contained less Zn, molybdenum and metallothionein (MT), while Zn supplementation produce increased concentrations of Zn and MT in the tissues, decreased the accumulation of Cu and alleviated liver damage associated with Cu overload and the toxic effects of pyrrolizidine alkaloids. A small number of sheep given Zn developed pancreatic damage.

The role Zn in biomembrane stabilisation and MT induction is discussed in relation to its protective role against Cu overload and pyrrolizidine toxicity.

Item Type: Thesis (PhD)
Murdoch Affiliation: School of Veterinary Studies
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Howell, John McC. and Dorling, Peter
URI: http://researchrepository.murdoch.edu.au/id/eprint/53589
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