Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glucagon is structurally related to secretin but inhibits the effects of secretin and cholecystokinin (CCK) on pancreatic secretion in vivo. Because secretin is a weak stimulant of pancreatic growth and potentiates the trophic effects of CCK, we hypothesized that glucagon might inhibit CCK-induced pancreatic growth. Four groups of 10 rats were injected with saline, glucagon (30 micrograms/kg, equimolar to a known trophic dose of secretin), cerulein (0.67 microgram/kg), or glucagon plus cerulein every 8 h for 5 days. The pancreas was excised, weighed, and assayed for total content of DNA, protein, amylase, chymotrypsinogen, and lipase. In control and glucagon-alone groups, the small intestine was also removed, weighed, and assayed for DNA, protein, and disaccharidase content. Glucagon alone decreased pancreatic DNA and increased lipase content. Compared with cerulein-treated animals, animals treated with glucagon and cerulein showed significant decreases in pancreatic weight and content of protein, amylase, and chymotrypsinogen. Although glucagon had significant effects on intestinal protein, maltase, and sucrase contents in certain segments, there was no clear pattern of response. The data suggest that glucagon may be an inhibitory regulator of pancreatic growth, acting to block the effects of CCK on pancreatic hypertrophy.
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PMID:Glucagon inhibition of cerulein-induced hypertrophy of the exocrine pancreas. 336 38

Certain effects of glucagon administration on newborn rat hepatocytes were studied using biochemical assays, electron microscopy and quantitative morphometry. Glucagon accelerated the normal postnatal hyaloplasmic glycogen breakdown and the lysosomal glycogen breakdown. The glucagon-treated animals showed an increased activity of the enzyme, acid a 1,4 glucosidase (maltase). The results suggest that the catabolism of lysosomal glycogen is controlled by those agents that regulate the catabolism of hyaloplasmic glycogen and that this control is mediated through changes in the activity of the lysosomal acid a 1,4 glucosidases.
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PMID:An electron microscopic and biochemical study of the effects of glucagon on newborn rat hepatocytes. 639 4

Glucagon is avidly degraded by the kidney, but the relative contribution of the luminal and basolateral tubular membranes to this process is unknown. We studied 125I-glucagon degradation by purified luminal (L) and basolateral (BL) tubular membranes prepared from rabbit kidney cortex, which showed enrichment vs. homogenate of marker enzyme activities (Na-K-ATPase for BL and maltase for L) of 10- and 14-fold, respectively. Renal homogenates and both tubular membrane fractions degraded glucagon avidly without reaching saturation even at pharmacologic concentration (10(-5) M) of the hormone. At physiologic concentration (3 x 10(-11) M) BL membranes degraded substantial amounts of glucagon (8.1 +/- 0.9 pg . micrograms protein-1 . h-1) even though at lesser rates (P less than 0.001) than the luminal fraction (33.3 +/- 1.9 pg . micrograms protein-1 . h-1). Competition experiments suggested that glucagon-degrading activity in both fractions includes both specific and nonspecific components, and the potency of different enzyme inhibitors to decelerate glucagon degradation was strikingly similar in the two membrane preparations. Glucagon degradation differed in several important aspects from the manner in which tubular membranes catabolize insulin, including absolute degradation rates and relative degrading capacity of the membranes vs. homogenates, both being substantially higher for glucagon. These results provide direct evidence that the renal metabolism of glucagon also involves its degradation by peritubular cell membranes.
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PMID:Glucagon degradation by luminal and basolateral rabbit tubular membranes. 682 62

Glucagon-like peptide-2 (GLP-2) stimulates small intestinal growth through induction of intestinal epithelial proliferation. To examine the physiology of GLP-2-induced bowel, mice were treated with GLP-2 (2.5 micrograms) or vehicle for 10 days. Small intestinal weight increased to 136 +/- 2% of controls in GLP-2-treated mice, in parallel with 1.4 +/- 0.1- and 1.9 +/- 0.5-fold increments in duodenal RNA and protein content, respectively (P < 0.05-0.001). Similarly, the activities of duodenal maltase, sucrase, lactase, glutamyl transpeptidase, and dipeptidyl-peptidase IV (215 +/- 28% of controls; P < 0.001) were increased by GLP-2. Oral or duodenal administration of glucose or maltose did not reveal any differences in the ability of GLP-2-treated mice to absorb these nutrients, possibly because of decreases in expression of the glucose transporters sodium-dependent glucose transporter-1 (SGLT-1) and GLUT-2. In contrast, absorption of leucine plus triolein was increased after duodenal administration in GLP-2-treated mice (P < 0.01-0.001). Finally, GLP-2 did not alter other markers of intestinal or pancreatic gene expression, including levels of mRNA transcripts for ornithine decarboxylase, multidrug resistance gene, amylase, proglucagon, proinsulin, and prosomatostatin. Thus induction of intestinal growth by GLP-2 in wild-type mice results in a normal-to-increased capacity for nutrient digestion and absorption in vivo.
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PMID:Intestinal function in mice with small bowel growth induced by glucagon-like peptide-2. 922 51

GLP-1, an incretin hormone of the enteroinsular axis with insulinotropic and glucagonostatic activity, is secreted after nutrient ingestion. GLP-1 is mainly produced by intestinal L-cells in the lower gastrointestinal tract (GIT); simple carbohydrates are absorbed in the upper GIT and alpha-glucosidase inhibition leads to augmented and prolonged GLP-1 release in normal subjects. In a cross-over study, 100 mg acarbose or placebo was administered simultaneously with 100 g sucrose to 11 hyperglycaemic Type 2 diabetic patients poorly controlled with diet and sulphonylureas. Plasma levels of GLP-1, insulin, C-peptide, glugacon, GIP, glucose and H2-exhalation were measured over 6 h. Differences in the integrated responses over the observation period were evaluated by repeated measurement analysis of variance with fasting values used as covariates. With acarbose, sucrose reached the colon 60-90 min after ingestion as indicated by a significant increment in breath hydrogen exhalation (p = 0.005). After an early GLP-1 increment 15 min after sucrose under both conditions, GLP-1 release was prolonged in the acarbose group (p = 0.001; significant from 210 to 360 min.). Initially (0-150 min), glucose (p = 0.001), insulin (p = 0.001), and GIP (p < 0.001) were suppressed by acarbose, whereas later there were no significant differences. Glucagon levels were higher with acarbose in the last 3 h of the 6 h observation period (p = 0.02). We conclude that in hyperglycaemic Type 2 diabetic patients, ingestion of acarbose with a sucrose load leads to elevated and prolonged GLP-1 release.
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PMID:Prolonged and enhanced secretion of glucagon-like peptide 1 (7-36 amide) after oral sucrose due to alpha-glucosidase inhibition (acarbose) in Type 2 diabetic patients. 963 23

Glucagon-like peptide-2 (GLP-2) is a potent intestinotropic factor in neonatal and adult animals. However, the GLP-2 responsiveness of the fetal intestine has not been established. To determine how stage of development affects the responsiveness to GLP-2, we examined GLP-2 receptor (GLP-2R) expression, gut morphology, and brush-border enzyme mRNA and activities in late-gestation fetal (n = 7) and parenterally fed neonatal (n = 7) piglets given GLP-2 (12.5 nmol/kg) twice daily for 6 days. The GLP-2R was expressed in the fetal and neonatal gastrointestinal tract. The biologically active GLP-2-(1-33) was undetectable (<5 pmol/l) in plasma of 98-day-gestation fetuses but increased significantly toward full term (115 days, 11 +/- 1 pmol/l) and in neonates fed by total parenteral nutrition (23 +/- 5 pmol/l). Exogenous GLP-2 had no effect on gut growth in fetuses but increased intestinal weight and villus height in neonates (P < 0.05). Crypt cell proliferation and the enzymes sucrase-isomaltase, lactase-phloridzin hydrolase, aminopeptidase A, and dipeptidyl peptidase IV were unchanged by GLP-2 in both groups. Aminopeptidase N mRNA and activity were increased in fetuses, while maltase mRNA and activity were increased in neonates. In conclusion, exogenous GLP-2 had different effects on small intestine growth and function in fetuses and neonates. This may be related to the normal developmental changes in intestine growth and function and to a maturation of the GLP-2R signaling pathways around the time of birth.
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PMID:GLP-2 has differential effects on small intestine growth and function in fetal and neonatal pigs. 1170 85