Pancreatic acinar cell function and morphology in rats fed zinc-deficient and marginal zinc-deficient diets

Subclinical zinc deficiency impairs pancreatic digestive enzyme activity and digestive capacity of weaned piglets

This study investigated the effects of short-term subclinical Zn deficiency on exocrine pancreatic activity and changes in digestive capacity. A total of forty-eight weaned piglets were fed ad libitum a basal diet (maize and soyabean meal) with adequate Zn supply (88 mg Zn/kg diet) during a 2-week acclimatisation phase. Animals were then assigned to eight dietary treatment groups (n 6) according to a complete randomised block design considering litter, live weight and sex. All pigs were fed restrictively (450 g diet/d) the basal diet but with varying ZnSO4.7H2O additions, resulting in 28·1, 33·6, 38·8, 42·7, 47·5, 58·2, 67·8 and 88·0 mg Zn/kg diet for a total experimental period of 8 d. Pancreatic Zn concentrations and pancreatic activities of trypsin, chymotrypsin, carboxypeptidase A and B, elastase and α-amylase exhibited a broken-line response to stepwise reduction in dietary Zn by declining beneath thresholds of 39·0, 58·0, 58·0, 41·2, 47·5, 57·7 and 58·0 mg Zn/kg diet, respectively. Furthermore, carboxypeptidase B and α-amylase activities were significantly lower in samples with reduced pancreatic Zn contents. Coefficients of faecal digestibility of DM, crude protein, total lipids and crude ash responded similarly to pancreatic enzyme activities by declining below dietary thresholds of 54·7, 45·0, 46·9 and 58·2 mg Zn/kg diet, respectively. In conclusion, (1) subclinical Zn deficiency impaired pancreatic exocrine enzymes, (2) this response was connected to pancreatic Zn metabolism and (3) the decline in catalytic activity impaired faecal digestibility already after 1 week of insufficient alimentary Zn supply and very early before clinical deficiency symptoms arise.

Zinc oxide-montmorillonite hybrid influences diarrhea, intestinal mucosal integrity, and digestive enzyme activity in weaned pigs

One hundred-eighty piglets (Duroc × Landrace × Yorkshire), with an average initial weight of 7.4 kg weaned at 27 ± 1 days of age, were used to evaluate the effects of dietary zinc oxide-montmorillonite hybrid (ZnO-MMT) on growth performance, diarrhea, intestinal mucosal integrity, and digestive enzyme activity. All pigs were allotted to five treatments and fed with the basal diets supplemented with 0, 250, 500, and 750 mg/kg of Zn as ZnO-MMT or 2,000 mg/kg of Zn as ZnO. The results showed that supplementation with 500 or 750 mg/kg of Zn from ZnO-MMT and 2,000 mg/kg of Zn from ZnO improved average daily gain, enhanced average daily feed intake, decreased fecal scores at 4, 8, and 14 days postweaning, reduced intestinal permeability which was evident from the reduced lactulose recovery and urinary lactulose/mannitol ratio, and improved the activities of protease, amylase, lipase, trypsin, and chymotrypsin both in pancreas and small intestinal contents of pigs as compared with the control. Supplemental 250 mg/kg of Zn from ZnO-MMT also decreased fecal scores at 8 and 14 days postweaning, decreased urinary lactulose/mannitol ratio, and improved chymotrypsin activity in pancreas and small intestinal contents as well as protease activity in small intestinal contents compared with control. Moreover, the above indexes of weanling pigs fed with 500 or 750 mg/kg of Zn as ZnO-MMT did not differ from those fed with 2,000 mg/kg of Zn as ZnO. The results demonstrated that supplementation with 500 or 750 mg/kg of Zn from ZnO-MMT was as efficacious as 2,000 mg/kg of Zn from ZnO in improving growth performance, alleviating postweaning diarrhea, and enhancing intestinal mucosal integrity and the digestive enzyme activities in pancreas and small intestinal contents of pigs. The results that feeding lower concentrations of ZnO-MMT to weanling pigs maintained performance will be beneficial for the environment and for sustaining swine production.

Effects of zinc levels on activities of gastrointestinal enzymes in growing rats

The present study investigated the effect of different zinc (Zn) levels on activities of gastrointestinal digestive enzymes of growing rats. Four diets including Zn-adequate (ZA; 46 mg/kg, control), Zn-deficient (ZD; 3 mg/kg), high Zn supply (ZH; 234 mg/kg) and pair-fed in which animals received the ZA diet at restricted amounts reflecting feed intake of the ZD group were fed to rats for 5 weeks. Dietary Zn was supplemented with ZnO. The results showed that Zn deficiency resulted in decreases in body weight, while ZH supply stimulated growth. The activities of sucrase, lactase and lipase were unaffected by dietary Zn levels. Maltase activity, however, was reduced in ZD group and elevated in ZH group. Amylase and protease activities were depressed by zinc deficiency. However, rats fed the Zn-repletion diet displayed higher activity of pepsin, pancreatic amylase and protease. In particular, ZH supply did have no effect on intestinal hydrolases activities. The present study suggested that zinc deficiency impaired the activities of digestive enzymes and growth of animals. However, ZH supply might improve the digestion of nutrients via increasing activities of gastrointestinal hydrolase and probably enhanced animal health.

Large doses of zinc oxide increases the activity of hydrolases in rats

The effect of pharmacological doses of zinc oxide (1000; 2500; 5000 mg per kg diet) and two levels of dietary protein on pancreatic and intestinal hydrolase activity in rats were studied. It was hypothesized that ZnO would increase intestinal and pancreatic hydrolase enzyme activity. Male Wistar rats, averaging 64 g body weight, were randomly allocated to dietary treatments (chow diets- meeting all NRC requirements) containing 10% or 15% protein supplemented with additional ZnO (above 100 mg/kg ZnSO(4)) as follows: 0.0; 0.1; 0.25; 0.5% w/w. Water and food were provided ad libitum. Animals were fed the diets for 10 days and body weights were recorded; after decapitation blood and organ samples were collected. Amylase, lipase, trypsin, and total protease activity of pancreatic homogenates and small intestinal contents were determined. ZnO supplementation dose dependently increased the plasma Zn concentration and significantly increased amylase, lipase, trypsin and total protease activity in pancreatic homogenates and small intestinal contents. The statistical analysis showed significant protein and ZnO interaction on the activity of amylase in the pancreas, and amylase, trypsin and total-protease in the small intestinal content. Therefore ZnO at high dietary concentration may influence the digestion of nutrients via increased hydrolase activity.

Filamentous inclusions in nonneoplastic and neoplastic pancreas: an ultrastructural and immunogold labeling study

Filamentous inclusions (FI) are unusual, irregularly shaped cytoplasmic inclusions, which are mostly found in acinar cell carcinomas of the pancreas and are consequently thought to be an abnormal zymogen granule type. This study describes identical inclusions in acinar, centroacinar, and small duct epithelial cells from nonneoplastic pancreas, as well as those found in tumor cells from a mixed acinar-endocrine pancreatic carcinoma. An ultrastructural and immunogold labeling demonstration indicates that these inclusions are aggregates of intermediate filaments immunoreacting with the anti-cytokeratin AE1/AE3 mixture and with V9 clone anti-vimentin monoclonal antibodies. Their pleomorphic appearance, variable immunoreactivity, and frequent association with lipid droplets and secondary lysosomes, mostly of the angulate type, led to the hypothesis that the FI undergo a degenerative remodeling pathway similar to that proposed for hepatic Mallory bodies. A survey of the literature on FI and human tumors suggests that they are a variably expressed ultrastructural feature of tumor cells originating from exocrine cell-containing tissues, namely the pancreas and gastrointestinal tract.

Analysis of zinc and other elements in rat pancreas, with studies in acute pancreatitis

Determination of the concentration of certain elements makes it possible to investigate the physiology of the pancreas. We used X-ray fluorescence to determine the concentrations of zinc and other elements in the pancreas of normal (control) rats and those with cerulein-induced pancreatitis. Ten elements (Zn, Ni, Fe, P, Ca, Cl, S, K, Ti, and Mn) were detected in controls. In the early stage of acute pancreatitis, the pancreatic concentrations of Zn, Ni, Fe, and P were significantly decreased (P < 0.05) and those of Ca and Cl were significantly increased (P < 0.05), compared with control levels. However, levels of S, K, and Ti did not differ significantly from the control values. Mn was detected in only some samples. The serum levels of Zn and Fe were significantly elevated (P < 0.05) in acute pancreatitis. These observations indicate that Zn and these other nine elements could play an important role in acute pancreatitis.

Zinc deficient diet consequences for pregnancy and offsprings of Wistar rats

Adult female Wistar rats (90 days old; weight 180 to 220 grams) were submitted to different zinc deficient diets (Zn; severe = 2.6 ppm; mild = 9.0 ppm and normal diet = 81.6 ppm), during 6 weeks. After this time they were coupled with normal male Wistar rats. No differences regarding fecundity and sterility were observed between the groups. During pregnancy, part of the animals from severe and mild Zn deficient groups received the same diet and the others received normal diet. The animals from the group receiving normal diet, were divided into other 3: the first received severe, the second mild Zn deficient diet and the third normal diet. During the study we observed that animals submitted to a Zn deficient diet (acute or chronic) had tendency to lower weight gain, lower weight of the offspring, lower serum levels of Zn in maternal and newborn (pool) blood. A significant reduction in the number of alive newborns was observed in the group of animals submitted to severe Zn deficiency. These data reinforces that Zn is a very important trace element overall during pregnancy.

Fibrillary cytoplasmic inclusions in neoplastic Paneth cells

Paneth cell differentiation was investigated in two colorectal carcinomas. Ultrastructural study showed a range of granules and, in one case, fibrillary cytoplasmic inclusions. Similar inclusions in normal Paneth cells have been associated with zinc deficiency. However, there was no clinical evidence of abnormal zinc metabolism in this patient, nor were inclusions seen in adjacent non-neoplastic Paneth cells. It is speculated that these fibrillary inclusions might reflect an intrinsic zinc-related metabolic defect in the tumour cells.

Role of zinc in treatment of experimental acute pancreatitis in mice

A study on the effect of zinc feeding on the survival rate as well as the levels of trypsinogen, alpha 2-macroglobulin, zinc, calcium, and magnesium in the plasma, pancreata, and livers of BALB/c mice fed a choline-deficient diet supplemented with 0.5% DL-ethionine (CDE diet) was undertaken. Feeding them a zinc-excess diet significantly increased the survival rate of mice with pancreatitis induced by CDE diet feeding. Trypsinogen concentrations in plasma and pancreas increased in mice fed a CDE diet and further increased in mice fed a zinc-deficient diet. The plasma alpha 2-macroglobulin levels in mice fed a zinc-deficient diet decreased compared to those fed a zinc-adequate or a zinc-excess diet. In mice with pancreatitis, zinc and calcium concentrations of pancreata increased and magnesium concentrations decreased compared to those of normal controls. The calcium concentrations in both livers and pancreata increased, but magnesium concentrations in these tissues decreased. These results suggest that altered mineral metabolism in the pancreas may have contributed to the pathophysiology of the mice with acute pancreatitis and that zinc supplementation in the diet may be therapeutic for pancreatitis.

Alcoholic pancreatitis in rats fed ethanol in a nutritionally adequate liquid diet

In an effort to develop a model of chronic alcoholic pancreatitis in Sprague-Dawley rats fed a nutritionally adequate diet, 3 groups of 15 animals each were fed Wayne Rodent-Blox ad libitum, Lieber-DeCarli diet with 40% of carbohydrate calories replaced by ethanol ad libitum and isocaloric amounts of Lieber-DeCarli diet respectively for a period of 18 months. Rats were anesthetized and basal and secretin-stimulated pancreatic juice was obtained. Pancreatic glands were isolated and divided into portions for histology, biochemical analyses, and cell fractionation. The homogenate, zymogen granule fraction, mitochondrial-lysosomal fraction, microsomal fraction and postmicrosomal supernatant as well as aliquots of pancreatic juice were analyzed for cathepsin B, acid phosphatase, beta-D-glucoronidase, arylsulphatase and leucine naphthylamidase. All of the ethanol-fed animals developed morphological changes akin to human chronic pancreatitis. There were focal areas of parenchymal degeneration with fibrosis, protein plug formation and tubular complexes. In the pancreatic tissue of animals fed ethanol, total protein, trypsinogen (and free trypsin) were increased and amylase was decreased. While acid phosphatase was increased in all of the particulate fractions, cathepsin B was increased in the zymogen granule and mitochondrial-lysosomal fractions. Basal and post-secretin pancreatic juice did not show a significant increase in digestive or lysosomal enzymes. It is suggested that focal degenerative changes may be due to trypsin generated by intracellular activation of digestive enzymes by lysosomal enzyme cathepsin B.

Effect of chronic feeding of ethanol diet of "average" fat content on rat pancreas

The present study was done to determine the influence of dietary fat on the effect of ethanol on pancreatic macromolecular content and secretion. Weight-matched groups of Sprague-Dawley rats were divided into controls fed Rodent-Blox ad libitum; American Institute of Nutrition-76 (AIN-76) diet containing 12% calories as fat with 36% of carbohydrate calories replaced with 5% (weight/volume) concentration of ethanol fed ad libitum pair fed with animals given isocaloric amounts of AIN-76 diet for three to six months. Compared with Rodent-Blox fed controls, tissue content of trypsinogen, chymotrypsinogen, amylase, and lipase; specific activity and concentration of trypsinogen, chymotrypsinogen; and concentration of amylase were decreased at six months in AIN-76 fed controls. These changes did not result from diminished food intake, but were due to adaptation to the liquid diet. Animals fed AIN-76 diet plus ethanol did not show significant difference in the total content, specific activity, concentration, and secretion of digestive enzymes compared with those animals pair fed isocaloric amounts of AIN-76 diet. Activation of trypsinogen by exogenous trypsin was lower in rats fed AIN-76 diet and a similar change was observed in animals fed AIN-76 diet with ethanol for six months. These findings are in contrast to increased secretion of proteases and decreased trypsin inhibitor observed previously in animals fed ethanol in a diet containing "high" fat. These data indicate that ethanol effect on the pancreas is modified by dietary intake of fat and/or carbohydrates.