Chronic pancreatitis in farmed pigs fed excessive zinc oxide.

Most of the pigs on a farm in Aichi Prefecture, Japan had chronic diarrhea and severe wasting. The pigs had consumed 8,000 ppm zinc oxide (ZnO) as a feed additive. The pancreas of each of 4 autopsied pigs was less than half the normal size. Acinar cells were considerably decreased. Epithelial duct-like cells were increased and tested positive for cytokeratin AE1/AE3, Ki67, PGP9.5, and Sox9. Pancreatic islet cells were decreased and shrunken. The α and δ cells were relatively decreased, and their distribution was abnormal. Islet cells were positive for PGP9.5. The livers and kidneys had high accumulations of zinc (Zn; 788 µg/g and 613 µg/g, respectively). Copper was deficient in the liver, likely as a result of Zn poisoning. Our immunohistologic examination suggested that the high dose of ZnO could influence the function of islet cells in addition to that of acinar cells. Given that colistin sulfate has been banned as a feed additive in order to reduce antimicrobial use in Japan, the use of ZnO in the livestock industry is expected to increase. Zn supplementation of pig feed must be monitored to prevent Zn poisoning and contamination of soil and water.

Morphological and histochemical changes occurring in the brain of rats fed large doses of zinc oxide.

An experimental study on the effect of feeding large doses of ZnO on the morphological and histoenzymatic pattern of the brain was conducted. 12 Wistar rats were given daily 100 mg of ZnO via a gastric tube. The poison was fed over a period of 10 days. The experimental rats developed minor morphological changes mainly in the hippocampal cortex and in the basal ganglia. A generalisation decrease of acP, ATPase, AChE and BuTJ activities along with an appreciable increase of TPPase and NsE activity was found in the brains of the intoxicated animals. An attempt was made to elucidate the pathogenesis of some of the findings.