Studies on zinc-induced pancreatic exocrine insufficiency and its consequences in the chick
Experiments were conducted to investigate the nature of zinc (Zn)-induced pancreatic exocrine damage, some of its consequences and its interaction with other nutrients, especially selenium (Se) and vitamin E (VE) in the chick. When fed excess Zn, the chick pancreas accumulated as much as an order of magnitude more Zn than the liver on a unit weight basis. The levels of activities of pancreatic secretory enzymes were significantly reduced by excess dietary Zn and distortion of the acinar pancreas structure, losses of zymogen granules and varying degree of fibrotic infiltration were observed histologically. The reduction of the level of pancreatic secretory enzyme activities was accompanied by a reduction of the quantity of enzyme proteins rather than a modification of enzyme activity. The rate of synthesis of pancreatic amylase, as assessed by the incorporation of {sup 3}H-leucine, was significantly decreased by excess dietary Zn. As consequences of Zn-induced pancreatic damage, the digestibility of dietary starch and tissue VE status were decreased, the latter effect being caused primarily by an impaired utilization of dietary source of the vitamin as determined by the appearance of {sup 3}H-{alpha}-tocopherol in the blood after an oral dose. Excess dietary Zn increased the Se status of the pancreas, but not those of the plasma and the liver. Supranutritional levels of Se and/or VE did not protect the pancreas against Zn-induced damage, nor did Se-deficiency exacerbate this damage. An in vitro inhibitory effect of Zn and some heavy metal ions on {alpha}-amylase activity was discovered and characterized by a non-competitive mechanism. This inhibitory effect could become an important modular of utilization of dietary starch under conditions of Zn toxicosis.
- Research Organization:
- Cornell Univ., Ithaca, NY (USA)
- OSTI ID:
- 7149729
- Resource Relation:
- Other Information: Thesis (Ph.D)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
PANCREAS
ENZYME ACTIVITY
ZINC
TOXICITY
AMYLASE
CHICKENS
DIET
EXPERIMENTAL DATA
INHIBITION
LEUCINE
SELENIUM
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VITAMIN E
AMINO ACIDS
ANIMALS
BIRDS
BODY
CARBOXYLIC ACIDS
DATA
DIGESTIVE SYSTEM
ELEMENTS
ENDOCRINE GLANDS
ENZYMES
FOWL
GLANDS
GLYCOSYL HYDROLASES
HYDROGEN COMPOUNDS
HYDROLASES
INFORMATION
ISOTOPE APPLICATIONS
METALS
NUMERICAL DATA
O-GLYCOSYL HYDROLASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
SEMIMETALS
VERTEBRATES
VITAMINS
560300* - Chemicals Metabolism & Toxicology
550201 - Biochemistry- Tracer Techniques