Effect of a Soybean Diet on Enzyme Content and Ultrastructure of the Rat Exocrine Pancreas

Fölsch, U.R.; Winckler, K.; Wormsley, K. G.

doi:10.1159/000197580

Cited by 73 publications

(17 citation statements)

References 9 publications

(9 reference statements)

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“…It seems that nodule formation can be reversed and, indeed, the development of pancreatic cancer prevented since even continuing azaserine does not result in pancreatic cancer in animals in which raw soya flour is discontinued after 12 weeks (10). Administration of raw soya flour for longer than 6 months results in irreversible nodule formation and progression to pancreatic carcinoma, despite change to non-soya flour-containing diets (unpublished observations).…”

Section: Reversibility Of Morphological Changesmentioning

confidence: 89%

“…Subsequently, overt nodules appear and increase in size (6). These changes correlate with the growth of the gland and with the increased secretory response to stimulants of the pancreas of these animals (7).…”

Section: Morphological Aspects Macroscopic Featuresmentioning

confidence: 99%

“…Similarly, rats receiving heated soya flour do not show abnormal increase in pancreatic weight during feeding for 2 years (4). Although a few microscopic and macroscopic nodules developed after feeding heated soya flour for 60 weeks or more, no animal fed heated soya flour developed pancreatic cancer (4 (6). These changes correlate with the growth of the gland and with the increased secretory response to stimulants of the pancreas of these animals (7).…”

Section: Morphological Aspects Macroscopic Featuresmentioning

confidence: 99%

“…It appears, therefore, that at least some of the new cells produced as a result of feeding raw soya flour are derived from apparently mature acinar cells, but the relative contribution from SPECIFIC ACTIVrTY EXPRESSED AS A RATIO OP CONTROL 6 7 WEEKS FIGURE 1. Specific activity of pancreatic DNA after 30 min of in vitro incubation with 3H-thymidine.…”

Section: Indices Of Cellular Replicationmentioning

confidence: 99%

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Effects of soybean flour on the pancreas of rats.

McGuinness¹,

Morgan²,

Wormsley³

1984

Environ Health Perspect

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We have reviewed the growth-promoting and carcinogenic effects of feeding raw soya flour to rats. If the raw soya flour-containing diets are fed for more than a year, about 10% of the animals develop pancreatic cancer. In addition, feeding raw soya flour markedly potentiates the action of even subthreshold amounts of pancreatic carcinogens. The raw soya flour therefore acts as a potent promoter, as well as a weak carcinogen. In view of this promotion, the rat fed raw soya flour is a sensitive model for screening pancreatic carcinogens.It is not known whether the human pancreas responds to dietary trypsin inhibitors in a manner similar to the rat. However, in view of the use of soya-based products in human nutrition-especially in infant foods-we urge that the effect of all soya-based products intended for human use be tested on the rat pancreas in long-term feeding studies, combined with subthreshold doses of azaserine to highlight any promoting activity of the product. It seems probable that if a product exerts no effect on the rat pancreas, the human pancreas will also be spared from noxious effects. Morphological Aspects Macroscopic FeaturesRaw soya flour-containing diets have been shown to produce enlargement of the rat pancreas after administration for as little as 10 to 20 days (1). The pancreatic enlargement has been shown to reflect both hypertrophy (defined as increase in cellular size and amount of protein per unit of DNA) (2) and also hyperplasia (increase in the amount of DNA and number of cells in the gland) (3). We have shown that the pancreatic growth-promoting effects continue, ifthe administration of raw soya flour is maintained, but becomes progressively more marked in an exponential manner at some time between 30 and 60 weeks of feeding raw soya flour-containing diets (4).During the period of pancreatic enlargement, the gland changes color to become dark red, reflecting increased vascularity and blood flow, as demonstrated by use of microspheres (unpublished results).Some time between 24 and 30 weeks after the start of raw soya flour-containing diets, small greyish patches become visible on the surface of the gland. Subsequently, overt nodules appear and increase in size (6). These changes correlate with the growth of the gland and with the increased secretory response to stimulants of the pancreas of these animals (7).After feeding raw soya flour-containing diets for 16 to 24 weeks, a few microscopic foci can be found scattered throughout the pancreas. The number and size of the nodules increases with the duration of feeding (4) Reversibility of Morphological ChangesThe pancreatic weights, protein content and morphological appearances revert to normal when rats are fed raw soya flour for 5 days (8), 4 weeks (9) and 6 months (unpublished observations) and then receive non-soyacontaining diets.If rats are fed raw soya flour for as long as 6 months and the diet is then changed to non-soya-containing chow, nodules are not found at death a year or more later, so that histologically the pancreas o...

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Section: Reversibility Of Morphological Changesmentioning

confidence: 89%

Section: Morphological Aspects Macroscopic Featuresmentioning

confidence: 99%

Section: Morphological Aspects Macroscopic Featuresmentioning

confidence: 99%

Section: Indices Of Cellular Replicationmentioning

confidence: 99%

See 2 more Smart Citations

Effects of soybean flour on the pancreas of rats.

McGuinness¹,

Morgan²,

Wormsley³

1984

Environ Health Perspect

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“…The long-term administration of STI in either the puri fied or naturally occurring forms or CCK to the adult rat has been known to cause a weight increase in the pancreas [5][6][7][8][9][10][11][12][13][14], This weight change was due to hyperplasia and hypertrophy of both secretory cells and other tissue con stituents of the pancreas [7,11]. Biochemical analyses of the enlarged pancreas showed elevations of DN A. protein and enzyme contents [5,6,[8][9][10][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Morphometry and Elemental Analysis of Rat Exocrine Pancreas following Administration of Trypsin Inhibitor

Sato¹,

Herman²

1990

Cells Tissues Organs

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The morphological responses of the exocrine pancreas of the adult male rat to soybean trypsin inhibitor (STI) were studied by ultrastructural morphometry and electron probe X-ray microanalysis. STI administered orally in drinking water for 14 days resulted in a 72% increase in the wet weight of the pancreas. This enlargement was due, largely, to an increase in acinar cell mass. Volume increases in the acinar cell mass and extra-acinar cell compartment were 72 and 30% respectively. The estimated total number of acinar cells in the mean exocrine pancreas was 500 million in the control and 630 million in the experimental group, representing an increase of 27%. Acinar cell volume was 1,790 µm³ for the control and 2,457 µm³ for the STI group. The pronounced morphometric changes of the organelles in the STI group were: the mean nucleolar volume increased by 56%; the volume of zymogen granular mass per cell increased by 93%; the volume of the Golgi complex and the condensing vacuoles per cell increased by 52 and 100% respectively, whereas the membrane area of the Golgi complex and the condensing vacuoles increased by 98 and 47% respectively. Spectral analysis of seven elements (Na, Mg, P, S, Cl, K and Ca) showed significant changes for nuclei, zymogen granules and mitochondria following STI: nuclei showed Na, P, K increased; zymogen granules showed Na, P, S, K increased, Cl decreased; mitochondrial particles showed Mg, P, Cl, Ca increased, and the mitochondrial matrix showed S decreased. The persistent uptake of STI probably resulted in a continual release of a trophic hormone acting on pancreatic tissue components consequently causing hyperplasia and hypertrophy of the exocrine pancreas to accommodate a heightened demand for synthesis of exportable proteins.

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Changes in numbers of pancreatic acinar cell nuclei and in DNA content during raw soya flour feeding in mice

Morgan

1990

Am. J. Anat.

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Nuclei of pancreatic cells were isolated by trypsin-detergent digestion of fresh tissue and stained with propidium iodide, and nuclear DNA was measured by flow cytometry. Samples were isolated from mice fed either chow or raw soya flour (RSF) for periods ranging from 1 day to 48 weeks, beginning at 4 weeks of age. In chow-fed mice, the pancreas contained about 80% diploid (2N) and 20% tetraploid (4N) cells at the start of the study, but tetraploidy gradually increased to about 40% 2 weeks later (6 weeks of age) and remained at this level from that time onwards. Low levels of octaploid nuclei (8N) were also present in some animals after 2 weeks. In RSF-fed mice, about 20% tetraploid nuclei were also present for 1 and 2 days after starting RSF, but by 4 days tetraploidy had increased significantly to 40% and by 14 days had further increased to 50%. This level was significantly higher than that seen in chow-fed animals and was maintained for up to 48 weeks. Significantly higher numbers of octaploid nuclei were also present in the RSF-fed animals. In both chow- and RSF-fed mice, most cells were mononuclear, averaging 70% in chow-fed and 64% in RSF-fed animals. This difference was significant. This study shows that the mouse pancreas differs from the rat pancreas in the absence of a large population of binucleate acinar cells and the presence of considerable nuclear tetraploidy. Raw soya flour feeding leads to significant changes in these features, but in this species these changes do not appear to predispose to neoplasia.

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Effect of a Soybean Diet on Enzyme Content and Ultrastructure of the Rat Exocrine Pancreas

Cited by 73 publications

References 9 publications

Effects of soybean flour on the pancreas of rats.

Effects of soybean flour on the pancreas of rats.

Morphometry and Elemental Analysis of Rat Exocrine Pancreas following Administration of Trypsin Inhibitor

Changes in numbers of pancreatic acinar cell nuclei and in DNA content during raw soya flour feeding in mice

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