Incretin hormones Flashcards
what is the incretin effect
there is an enhanced insulin secretion in response to oral glucose compared to IV glucose
what are incretins
small peptide hormones released from the GI tract
when are incretins released
in response to food intake
what does incretin release do
enhance the effect of insulin secretion in reponse to glucose
where re incretins released from
GI tract
two main incretins
GIP = glucose-dependent insulinotropic polypeptide GLP-1 = glucagon-like peptide
what is GIP
glucose-dependent insulinotropic polypeptide
42 AA peptide
what is GIP synthesised from and where
proGIP from K cells in the proximal GI tract
what is the proximal GI tract
upper part; duodenum and proximal jejunum
where does GIP go
from GI tract to islet cells, carried in the circulation
what is GLP-1
glucagon-like peptide
30 AA peptide
what is GLP1 synthesised from and where
proglucagon in the L cells in the distall GI tract
what is the distal GI tract
Colon & ileum
where are K cells
proximal GI tract
where are L cells
distal GI tract
what do K cells produce
GIP
what do L cells produce
GLP-1
what is proglucagon a precursor of
in alpha cells = glucagon
in L cells = GLP-1, glicentin & GLP-2
5 beneficial effects of GLP-1
- stimuates insulin secretion
- decreases glucagon secretion
- delays gastric emptying
- decreases appetite
- increases beta cella mass via increased proliferation and reduced apoptosis
when is the incretin effect reduced
T2D
how is the incretin effect changed in T2D
people with T2D will have a lower than expected insuliin respose to oral glucose. There is not a big difference seen between IV and Oral glucose as there is with the incretin effect
What area GIP levels like in T2D compared to normal?
relatively the same but has reduced effect to stimuate insulin secretion
What area GLP-1 levels like in T2D compared to normal?
may be decreased
what degrades GLP 1 and GIP
DPP-E depeptidyl peptidase 4
