Pathological analysis of lesions in the exocrine pancreas of rats induced by Zinc Maltol

The pancreas plays an important role in the homeostasis of zinc (Zn), a nutritionally essential metal. In several previous studies, Zn ions induced inflammatory changes in the exocrine pancreas; however, little is known about Zn complexes. In this study, we microscopically, immunohistochemically, and ultrastructurally examined pancreatic lesions in Sprague-Dawley (SD) rats induced by a 4-week repeated oral dose toxicity study of Zinc Maltol (ZM), a zinc (II) complex. ZM induces acinar atrophy and increases the number of duct-like structures. Immunohistochemistry revealed a decrease in the number of trypsin-positive cells, and an increase in the number of SOX9-positive cells. Interstitial fibrosis and macrophage infiltration also correlated with the degree of acinar atrophy. Electron microscopic evaluation revealed that the acinar cells that lost granules were surrounded by fibroblasts and collagen fibers. In conclusion, we provided a detailed description of ZM-induced pancreatic lesions in SD rats.

Safety evaluation of zinc methionine in laying hens: Effects on laying performance, clinical blood parameters, organ development, and histopathology

The study was conducted to investigate whether high-dose zinc methionine (Zn-Met) affected the safety of laying hens, including laying performance, hematological parameters, serum chemical parameters, organ index, and histopathology. A total of 540 20-week-old Hy-Line White laying hens was randomly allocated to 6 groups with 6 replicates of 15 birds each. Birds were fed diets supplemented with 0 (control), 70, 140, 350, 700, or 1,400 mg Zn/kg diet as Zn-Met. The experiment lasted for 8 wk after a 2-week acclimation period. Results showed that dietary supplementation with 70 or 140 mg Zn/kg diet as Zn-Met significantly increased average daily egg mass (ADEM), laying rate (LR), and feed conversion ratio (FCR) (P < 0.05) and lowered broken and soft-shelled egg ratio (BSER) (P < 0.05) in comparison with the control group; no significant differences were detected among hens fed with 0, 350, or 700 mg Zn/kg as Zn-Met (P > 0.05); hens administered 1,400 mg Zn/kg showed a significant increase in BSER and remarkable decreases in ADEM, LR, and FCR (P < 0.001). There were no significant differences among hens receiving 0, 70, 140, 350, or 700 mg Zn/kg as Zn-Met in serum chemical parameters (P > 0.05); supplementation with 1,400 mg Zn/kg as Zn-Met remarkably elevated the concentrations of serum total bilirubin (TBILI), glucose (GLU), uric acid (UA), and creatinine (CRE) (P < 0.001), and enhanced activities of serum glutamic oxalacetic transaminase (GOP) and alkaline phosphatase (AKP) (P < 0.001) compared with the control group. No significant histopathological changes were found in hens administered 0, 70, 140, 350, or 700 mg Zn/kg as Zn-Met, while significant histological lesions were observed in the heart, liver, lung, and kidney tissues of hens receiving 1,400 mg Zn/kg as Zn-Met. No significant differences were detected in hematological parameters or organ index (P > 0.05). In conclusion, a nominal Zn concentration of 700 mg/kg as Zn-Met is considered to be no-observed-adverse-effect level following daily administration to hens for 56 days.

Zinc supplement modulates oxidative stress and antioxidant values in rats with severe acute pancreatitis

Oxidative stress is a main factor in the pathogenesis of severe acute pancreatitis (SAP). The ability of zinc (Zn) to retard oxidative processes has been recognized for many years. This study aims to examine the levels of free oxygen radicals and antioxidant enzyme in SAP rats and know the effect of Zn supplementation on free oxygen radicals and antioxidant system in rats with SAP. Forty-five male Wistar rats were divided into three groups-the SAP group (n=15), the Zn-treated group (n=15), and the controlled group (n=15). For the SAP group, sodium taurocholate is injected into the pancreatic duct to induce SAP; for the Zn-treated group, Zn (5 mg/kg) is subcutaneously injected immediately after injection of 5% sodium taurocholate. Firstly, the activity of erythrocyte glutathione peroxidase (GSH-Px), erythrocyte superoxide dismutase (SOD), and the content of plasma malondialdehyde (MDA), which are the toxic products of oxidative stress, is measured. Secondly, the levels of free oxygen radicals in the liver and kidney are detected. The result showed that the activity of GSH-Px and SOD was lower in the SAP group than that in the controlled group, although the content of plasma MDA increased. However, the activity of SOD and GSH-Px in the Zn-treated group was not significantly decreased after comparing with the controlled group; in the mean time, the content of MDA was not significantly increased either. Moreover, the content of free radical in liver and kidney was higher in the SAP group compared with the controlled group, but the content of free radical in the Zn-treated group was not higher than that in the controlled group (p>0.05). All of the above indicated that Zn may recover the activity of free radical-scavenging enzymes and decrease the content of free radical for the SAP group rats. In conclusion, the content of free radical increase may be one of the reasons that SAP rats are injured, and it is possible for Zn to be used to treat SAP through scavenging free radical and increasing the activity of SOD and GSH-Px of erythrocyte.

Haemolytic anaemia and acute pancreatitis associated with zinc toxicosis in a dog

We describe a case of zinc toxicity in a 14-month-old, female, neutered, Cavalier King Charles spaniel with a 48-hour history of haematochezia, icterus and collapse. Regenerative anaemia with a packed-cell volume of 7 per cent was seen. Prior to referral, radiography had revealed a gastric, metallic foreign body which was removed at exploratory laparotomy. On presentation, the dog was comatose, hypothermic and bradycardic - resuscitation was performed successfully, but the dog then displayed marked abdominal pain. The dog died 12 hours after presentation. At postmortem examination, the animal showed severe icterus. Both kidneys were diffusely dark red; the pancreas was diffusely pale and nodular. Histopathological examination revealed evidence of intravascular haemolysis with blood vessel lumens containing haemoglobin. The renal tubules also contained large amounts of intraluminal haemoglobin with haemoglobin crystals scattered throughout the cortex and medulla. The pancreas exhibited multifocal coagulative necrosis, surrounded by a neutrophil-dominated inflammatory infiltrate. Zinc levels were markedly increased above the normal reference range in both liver and kidney. This report describes the clinical and pathological findings of a case of acute zinc toxicity in a dog following ingestion of a metallic object which resulted in marked haemolytic anaemia and acute pancreatitis.

The ubiquitous role of zinc in health and disease

OBJECTIVE

To review zinc physiology and pathophysiology and the importance of zinc toxicity and deficiency in veterinary patients.

DATA SOURCES

A review of human and veterinary medical literature.

HUMAN DATA SYNTHESIS

There is a significant amount of original research in humans and animals on the role of zinc in multiple organ systems. There is also significant data available on human patients with zinc abnormalities.

VETERINARY DATA SYNTHESIS

Zinc deficiency has been studied in dogs with genetic disease and dietary deficiency leading to dermatological disease and immune deficiency. Zinc toxicity has been described after ingestion of metallic foreign bodies containing zinc.

CONCLUSIONS

Historically, the role of zinc in health and disease has been studied through patients with toxicity or severe deficiency with obvious clinical signs. As the ubiquitous contribution of zinc to structure and function in biological systems was discovered, clinically significant but subtle deficiency states have been revealed. In human medicine, mild zinc deficiencies are currently thought to cause chronic metabolic derangement leading to or exacerbating immune deficiency, gastrointestinal problems, endocrine disorders, neurologic dysfunction, cancer, accelerated aging, degenerative disease, and more. Determining the causal relationships between mild zinc deficiency and concurrent disease is complicated by the lack of sensitive or specific tests for zinc deficiency. The prevalence of zinc deficiency and its contribution to disease in veterinary patients is not well known. Continued research is warranted to develop more sensitive and specific tests to assess zinc status, to determine which patients are at risk for deficiency, and to optimize supplementation in health and disease.

Attenuation of Zn-induced acute pancreatitis in Wistar rat fed on Cu- and Mg- enriched modified poultry egg Psi

Zinc (Zn) consumption has increased in many populations either due to the increased intake of Zn-fortified foods as in the USA or in agricultural food stuffs as in some Indian states during the last decade. Its excessive intake has been reported to induce acute pancreatitis (AP) in many studies due to increase in oxidative stress that was further reported to cause Cu and Mg deficiencies. This led us to design a modified poultry egg (ME(Psi)) enriched with Cu and Mg along with other antioxidants, and its efficacy on Zn-induced AP was studied in male Wistar rats. In one set, the rats were fed on equacaloric semi-synthetic basal diet containing 20 mg Zn/kg diet (control, group I), and Zn-induced AP-I diet and AP-II diet containing 40 and 80 mg Zn/kg diet (groups II and III) for 180 days, respectively. In another set, the rats were initially fed on Zn-induced AP-I and AP-II diets for 90 days and then shifted to ME(Psi)-mixed Zn-induced AP-I and AP-II diets in groups IIME and IIIME for another 90 days. At the end of the experiment, data displayed increased serum and urinary Zn, Cu, and Mg levels in groups II and III rats, which were reduced and approached closer to control group I after ME(Psi) feeding in groups IIME and IIIME rats. Transmission electron microscopic studies of acinar cells revealed progressive dilation, vesicularization, and degeneration of endoplasmic reticulum (ER), and decrease in zymogen granules (ZG) in groups II and III rats in contrast to their curvilinear or concentric long parallel running cisternal profile of ER in control group I. The treatment of ME(Psi) helped in the restoration of the ER profile and ZG number, approaching closer to the control group I. The degree of recovery was dependent upon the degree of toxicity caused by the amount of Zn given in the diet. The results of this study suggest that ME(Psi)-mixed diet can protect the acinar cells from the deleterious effects of Zn by decreasing the oxidative stress.