Soybean lectin stimulates pancreatic exocrine secretion via
cholecystokinin-a receptors in rats.
Jordinson, Mark, Pierre H. Deprez, Raymond J. Playford, Sharon Heal,
Thomas C. Freeman, Malcolm Alison, John Calam.
Departments of Medicine, *Haematology and Histopathology, Royal
Postgraduate Medical School, Hammersmith Hospital, Du Cane Road,
London W12 ONN, UK
APStracts 2:0186G, 1995.
Rats fed raw soya flour show pancreatic growth due to excessive
cholecystokinin(CCK) release. Soybean trypsin inhibitors are
implicated, but rats fed soybean lectin also showed pancreatic
growth. Therefore we studied the effect of soybean lectin on
pancreatic protein secretion in anaesthetised rats. Intraduodenal
administration of 30 mg of raw soybean flour stimulated a 1-hour
integrated rise in pancreatic protein output of 2.2 + 1.1 mg/h (mean
+ SEM) in rats with bile pancreatic(BP) juice returned to the
duodenum. Selective removal of the lectin by affinity to N-acetyl-D
-galactosamine-agarose abolished the response; -0.1 + 0.2 mg/h. Adding
back the 84 [mu]g of lectin restored the output to 2.2 + 0.9 mg/h.
With BP juice returned to the duodenum 84 [mu]g of lectin required
the co-presence of protein and protease inhibitors to have this
effect. However when BP juice was not returned, 84 [mu]g of lectin
given alone produced a pancreatic response of 3.2 + 1.3 mg/h. Plasma
CCK concentrations rose significantly from 6.6 + 1.9 to 14.3 + 2.9
pmol/l, and the pancreatic response was abolished by CCK-A receptor
blockade; 0.0 + 0.1 mg/h. Conclusions: Soybean lectin plays a major
role in the acute stimulation of pancreatic protein secretion by raw
soya flour. The lectin releases CCK and the effect is mediated by
CCK-A receptors.
Received 28 July 1994; accepted in final form 31 July 1995.
APS Manuscript Number G281-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.