Role of the Gastrointestinal Tract in Obesity Flashcards
In what part of the brain is weight controlled?
in the hypothalamus
What are the two types of neurons in the arcuate nucleus involved in controlling food intake?
NPY neurons and POMC neurons
What peptides are produced by the NPY neurons and what is their impact on food intake?
NPY and AGRP - stimulate food intake
What peptides are produced by the POMC neurons and what is their impact on food intake?
alphaMSH and CART - inhibit food intake
What hormones act on the hypothalamus to stimulate food intake?
ghrelin and ILP-5
What hormones act on the hypothalamus to inhibit food intake?
leptin, CCK, PYY, GLP-1, oxyntomodulin, insulin, amylin, pancreatic polypeptide, uroguanlylin
Where is ghrelin released from?
the stomach
What is the action of ghrelin?
stimulates release of NPY and AGRP to stimulate food intake and also increases synthesis of NPY
What is the diurnal variation of ghrelin?
peaks at meal times
Where is ILP-5 released from?
the colon
What is the action of ILP-5?
stimulates food intake
Where is CCK released from?
the I cells of the upper small intestine
What is the action of CCK?
inhibits food intake and also stimulates emptying of the gall bladder and release of digestive enzymes
How does CCK have an effect on the brain?
via the CCK1R on the vagus nerve
Why wouldn’t CCK be an appropriate treatment for obesity?
because although it would decrease the meal size it would increase the frequency of meals
Where is PYY released from?
L cells of the ileum
Which enzyme converts PYY to its active form?
DPP-4
What is the action of PYY?
reduces food intake via the Y2 receptor
Where is oxyntomodulin released from?
L cells in the intestine
What is the action of oxyntomodulin?
inhibit food intake and increases energy expenditure
What receptor does oxyntomodulin act on?
the GLP-1 receptor
What enzyme inactivates oxyntomodulin?
DPP-4
Where is GIP released from?
duodenal and jejunal K cells
What is the action of GIP?
activates lipoprotein lipase, stimulates insulin secretion
What is the action of GLP-1?
stimulates insulin secretion, increases period of post prandial satiety, slows gastric emptying
What is liraglutide?
a GLP-1 analogue
What is the action of uroguanylin?
decreases food intake and increases fluid absorption from the gut
How do gut hormones defend body weight?
because even 1 year after weight loss their levels are either increased or decreased to promote food intake
