Control of appetite

Question 1

Define satiation and satiety. Define hunger and appetite

Answer 1

satiation - feeling full and terminates meal

satiety - feeling of repletion that inhibits further meals

Question 2

What part of the brain controls food intake?

Answer 2

hypothalamus

Question 3

What part of the hypothalamus integrates appetite signals? With respect to the BBB, why can gut hormones get to it?

Answer 3

arcuate nucleus (ARC) 
it isn't protected by the BBB

Question 4

What does orexigenic and anorexigenic mean?

Answer 4

orexigenic - stimulate food intake

anorexigenic - inhibit food intake

Question 5

Release of what 2 compounds stimulates food intake? Where do they come from and where do they go?

Answer 5

food intake - stimulated by AgRP and NPY

from the arcuate nucleus (ARC) to the orexigenic neurons

Question 6

What 2 compounds inhibit food intake? Where do they come from and where do they go?

Answer 6

POMC and CART

from the arcuate nucleus (ARC) to anorexigenic neurones

Question 7

POMC is modified to make what? What compound is an antagonist to the receptor?

Answer 7

generate melanocortins to act on melanocortin receptors

AgRP is the antagonist of the melanocortin receptor

Question 8

What cells secrete leptin? Insulin? Ghrelin? CCK?

Answer 8

leptin - adipose tissue
insulin - pancreas
ghrelin and CCK- GIT

Question 9

Where does CCK act?

Answer 9

vagus nerve

Question 10

What hormones inhibit and what hormones promote appetite?

Answer 10

inhibit - leptin, insulin, CCK

promote - ghrelin

Question 11

List some of the hormones that inhibit appetite. 6

Answer 11

CCK
GLP-1
oxyntomodulin
PYY3-36
apolipoprotein A-IV
enterostatin

Question 12

If food intake drops, what happens to leptin and why?

Answer 12

decrease in leptin so you’d remove the inhibitory effects of leptin

Question 13

What is Leptin’s effects on the brain?

Answer 13

inhibits NPY AgRP release
activates the PMC/CART neurons
from appetite stimulation to appetite suppression

Question 14

Where does insulin act on in the brain to inhibit appetite?

Answer 14

actions on the arcuate nucleus (ARC)

Question 15

What does Ghrelin do in the brain?

Answer 15

Acts on arcuate nucleus or brain stem to stimulate food intake through NPY and AgRP

Question 16

Where is PYY secreted from and under what conditions? Explain the physiological mechanism of PYY’s actions on the brain.

Answer 16

secreted from distal GIT dependent on nutrient intake or stimulated by CCK, gastric acid, bile
cleaved at acts at NPY Y2 receptor

decreases food intake

Question 17

Where is CCK secreted from and under what conditions?

Answer 17

released from duodenum and jejunum

response to FAs

Question 18

What neurotransmitter is involved when palatable food is eaten?

Answer 18

dopamine

Question 19

Where is dopamine involved upon food consumption

Answer 19

dopamine release in dorsal striatum

Question 20

What drug helps in weight loss involving dopamine?

Answer 20

bupropion is a dopamine reuptake inhibitor - more reward with less pleasurable food

Question 21

What receptor is involved in food reward

What drug is the antagonist for it?

Answer 21

cannabinoid receptor (CB1)

rimonabant - CB1 receptor antagonist

Question 22

What does orlistat do?

What is a big side effect of orlistat?

Answer 22

inhibits gastric and pancreatic lipase - minimal absorption

side effect - steatorrhea

Question 23

what does orlistat need to be combined with? Under what conditions should it be combined with?

Answer 23

low fat diet, take one immediately before each main meal

if meal contains no fat then miss dose

Question 24

What does saxenda do?

Answer 24

GLP-1 receptor agonist
appetite suppression - increases POMC/CART
GLP-1 supresses dopamine - reward pathway

Question 25

What does GLP-1 do?

Answer 25

can reduce high fat food intake by suppressing dopamine signalling - effect on reward pathways