Insulin Regulation of Secretion

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1. Regulation of Insulin Secretion Dr. Rajendran. S www.medicinemcq.com 1

2. Insulin secretion by pancreas Blood glucose regulates insulin secretion Insulin regulates blood glucose www.medicinemcq.com 2

3. Plasma glucose Direct feedback effect on pancreatic beta cells When plasma glucose ↑ Insulin secretion ↑ When plasma glucose ↓ Insulin secretion ↓ G reat precision www.medicinemcq.com 3

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5. Insulin and Glucose Insulin regulates blood glucose Glucose production by the liver Uptake and utilization in peripheral tissues Muscle Adipose tissue Liver www.medicinemcq.com 5

6. Normal FBS 80 to 90 mg/100 ml Rate of insulin secretion is low Plasma glucose < 75 mg / dl Insulin secretion inhibited www.medicinemcq.com 6

7. Plasma glucose > 75 mg/ dL Stimulate insulin synthesis and insulin secretion Blood glucose > 100 mg/100 ml Insulin secretion rises rapidly www.medicinemcq.com 7

8. Maximal insulin secretion Glucose between 300 and 500 mg / dl www.medicinemcq.com 8

9. GLUT 2 Glucose enters B cells via GLUT 2 Pancreas Beta cell glucose sensor Insulin independent www.medicinemcq.com 9

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14. Glucokinase (Hexokinase IV) Controls glucose-regulated insulin secretion Phosphorylation Rate-limiting step in glucose metabolism in the   beta cell and insulin release www.medicinemcq.com 14

15. Enteroinsular axis Incretins GI hormones that potentiate insulin secretion Cause 50% of the insulin released after a meal www.medicinemcq.com 15

16. Major incretins Glucagon Like Peptide-1 (GLP-1) Gastric Inhibitory Peptide (GIP) www.medicinemcq.com 16

17. Gastrointestinal peptide hormones Released from small-intestinal endocrine cells postprandially Reach the beta cells through the bloodstream Increase the sensitivity of islet cells to glucose www.medicinemcq.com 17

18. Incretin effect Insulin secretion greater after oral than after intravenous glucose administration www.medicinemcq.com 18

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23. GLP-1 Stimulates insulin secretion Increases beta cell mass Inhibits glucagon secretion Delays gastric emptying www.medicinemcq.com 23

24. GLP-1 Raises levels of cAMP Activates cAMP-dependent protein kinase A Amplify the Ca 2+  signal by decreasing Ca 2+  uptake by cellular stores www.medicinemcq.com 24

25. GIP Stimulates insulin secretion when glucose levels are elevated Decreases glucagon-stimulated hepatic glucose production www.medicinemcq.com 25

26. Amino acids Amplify the glucose-induced release of insulin from the beta-cell Stimulate insulin release in the absence of glucose Most potent Arginine Lysine Leucine www.medicinemcq.com 26

27. Amino acids Amino acid metabolism and ATP generation Elevated beta-cell Ca 2+  concentrations www.medicinemcq.com 27

28. Lipids Only minor effects on insulin release www.medicinemcq.com 28

29. Ketone bodies Promote the secretion of insulin www.medicinemcq.com 29

30. Stimulation of adrenergic receptors  Beta 2   Enhance insulin secretion Alpha 2   Inhibits insulin release www.medicinemcq.com 30

31. Stimulation of ANS Suppresses the secretion of insulin Stimulation of alpha 2  adrenergic receptors and inhibition of insulin secretion Hypoxia Hypoglycemia Exercise Hypothermia Surgery Severe burns www.medicinemcq.com 31

32. Adrenergic receptor antagonists Alpha 2 Increase basal concentrations of insulin Beta 2 Decrease basal concentrations of insulin www.medicinemcq.com 32

33. Somatostatin Inhibit insulin secretion www.medicinemcq.com 33

34. Catecholamines and somatostatin Inhibit insulin secretion Through G protein–coupled receptor ( GPCR ) mechanisms Inhibit adenylate cyclase Modify Ca 2+  and K +  channel gating. www.medicinemcq.com 34

35. Glucagon Stimulates insulin secretion Insulin inhibits glucagon secretion www.medicinemcq.com 35