15 - Appetite Regulation

Question 1

Arcuate nucleus

Answer 1

Main centre for appetite regulation (in the hypothalamus)

Question 2

NPY/Agouti related peptide

Answer 2

Laterally

Appetite stimulating

Question 3

Cocaine related transcript (CART) and pro opiomelanocortin (POMC)

Answer 3

Medially

Appetite inhibiting

Question 4

Where is agouti found

Answer 4

Controls hair colour

AgRP found in the hypothalamus hypothalamus co-current with cells producing NPY

Question 5

Function of agouti

Answer 5

Acts as a melanocortin receptor antagonist

Question 6

What drops AgRP levels

Answer 6

Leptin

Insulin

Question 7

Orexigenic (Appetite stimulating) factors

Answer 7

Peripheral - Ghrelin

Central - MHC, AgRP, NPY

Question 8

Anorexigenic (Appetite inhibiting) factors

Answer 8

Central - POMC, CART, 5-HT

Peripheral - PYY, GLP-1, Leptin, Insulin, CCK

Question 9

POMC control

Answer 9

POMC –> Melanocortin –> Binds to melanocortin receptor (MCR-4) –> Controls energy balance

Question 10

POMC deficient

Answer 10

Develop hyperphagia and obesity

Question 11

Deletion of MC4R

Answer 11

Hyperphagia
Mutation in 4-5% of obese
5% cause of childhood obesity

Question 12

Effect of serotonin on appetite

Answer 12

5-HT is anorexigenic

Question 13

What receptors does 5-HT act on in appetite regulation and the function

Answer 13

Htr1b and Htr2c

• increase signalling from POMC neurons (Htr2c)
• decrease AgRP neuron signalling (Htr1b)

Question 14

What does ghrelin stimulate + where is it released

Answer 14

NPY neurons to increase appetite

Stomach

Question 15

Where are ghrelin receptors

Answer 15

Vagus nerve

stomach

Question 16

What type of release is ghrelin released n

Answer 16

Circadian release

Question 17

Where is GLP-1 released and what secretes it

Answer 17

L cells secrete in the ileum

Question 18

Function of GLP-1

Answer 18

Decreases appetite by stimulating insulin and POMC and inhibits NPY

Question 19

Function of PYY 3-36

Answer 19

Inhibits NPY and stimulates POMC
Like glp-1
Antagonises ghrelin

Question 20

Pathway of PYY 3-36

Answer 20

PYY 3-36 synthesised in the gut
reaches hypothalamus via blood
PYY inhibits NPY neurons via Y2 receptor and stimulates POMC neurons
Food intake declines

Question 21

Where is cholecystokinin released

Answer 21

CCK is secreted from I-type enteroendocrine cells in the duodenum/jejunum in the presence of fat

Question 22

Function of CCK

Answer 22

Acts to supress appetite
Reduce gastric emptying
Stimulate production of bile + contraction of GB + stimulate enzymes to digest fat

Question 23

What mutation do the Otsuka Long-Evans Tokushima Fatty rats hae

Answer 23

Mutations in CCK-A (cck receptor)

obese and t2d

Question 24

Where is leptin secreted from

Answer 24

Adipose tissue (fat cells)

Question 25

What is leptin release

Answer 25

Circadian release

Question 26

Function of leptin

Answer 26

Inhibits NPY and AgRP

Question 27

Genetic defects of leptin

Answer 27

Defective leptin - ob | Defective leptin receptor - db or zucker rat

Question 28

Phenotype of ob/ob and db/db mice

Answer 28

``` Obese Increased appetite Diabetes Overexpression of NPY, AGRP Decreased expression of POMC ```

Question 29

What can leptin injections treat

Answer 29

Leptin deficient children | reduces body weight and fat mass

Question 30

Leptin resistance

Answer 30

Caused by loss of function mutations in the leptin receptor | therefore leptin administration has little effect

Question 31

What is lipodystrophy

Answer 31

Selective loss of body fat | low leptin levels

Question 32

What forms malonyl coa

Answer 32

from excess acetyl-coA to synthesis FA

Question 33

What controls levels of Malonyl coA

Answer 33

AMPK (Phosphorylation of synthesise enzymes) | + calcium regulated with ghrelin?

Question 34

What does malonyl COa INHIBIT

Answer 34

the carnitine shuttle | so no breakdown of fat/triglycerides

Question 35

Cannabinoids on appetite

Answer 35

Increase appetite | CB1 receptors in hypothalamus increases palatability of food