Appetite regulation

Question 1

What is the name of a substance which increases food intake (stimulates appetite)?

Answer 1

Orexigen

Question 2

What is cachexia disorder?

Answer 2

a “wasting” disorder that causes extreme weight loss and muscle wasting, and can include loss of body fat. This syndrome affects people who are in the late stages of serious diseases like cancer, HIV or AIDS, COPD, kidney disease, and congestive heart failure (CHF).

Question 3

What is the name of a substance which inhibits food intake?

Answer 3

Anorexigen

Question 4

Where in the brain are internal cues such as the levels of blood hormone detected?

Answer 4

The arcuate nucleus

Question 5

What is consequence of a lesion in the arcuate nucleus?

Answer 5

Personal unable to detect internal signals
- if food palatable- Will eat until it can eat no more, can not detect satiety

• If food unpalatable- will starve to death- can not detect hunger

Question 6

Which neurons in the hypothalamus stimulate hunger and which ones stimulate satiety

Answer 6

Hunger-
‘Agouti-related peptide*’ (AGRP) & ‘Neuropeptide Y’ neurones (NPY) neurones

Satiety-
Cocaine & amphetamine related transcript’ neurones (CART) & ‘Pro-opiomelanocortin (POMC)’ neurones

Question 7

What is the name of the main hunger signal and how does it stimulate hunger?

Answer 7

Ghrelin

It activates ‘Agouti-related peptide*’ (AGRP) & ‘Neuropeptide Y’ neurones (NPY) neurones in the arcuate nucleus in the hypothalamus

This inhibits ‘Cocaine & amphetamine related transcript’ neurones (CART) & ‘Pro-opiomelanocortin (POMC)’ neurones

This stimulates hunger

Question 8

What are the names of the 3 main satiety signals and how do they stimulate hunger?

Answer 8

CCK, GLP-1, insulin, leptin

They excite
‘Cocaine & amphetamine related transcript’ neurones (CART) & ‘Pro-opiomelanocortin (POMC)’ neurones in the arcuate nucleus in the hypothalamus

This inhibits
Agouti-related peptide*’ (AGRP) & ‘Neuropeptide Y’ neurones (NPY) neurones

Question 9

What is the name for the cells responsible for assessing the nutrient environment in the gut?

Answer 9

Enteroendocrine Cells

Question 10

What is the function of the vagus nerve in appetite regulation?

Answer 10

Chemoreceptors on the vagus nerve is activated by signals released by the Enteroendocrine Cells.

Mechanoreceptors on the vagus nerve is stimulated by stretch- gastric enlargement = satiety

The dorsal vagal complex is connected to the arcuate nucleus

Question 11

What is the name of the adipose tissue which produces leptin?

Answer 11

Adipokine

Question 12

How is leptin released?

Answer 12

Secretion diurnal- not related to food intake

Does not respond over short term but over longer term

Circulating levels are associated with body fat

Question 13

Which cell release PYY3-36 hormone, what are they released in response to and what effect do they have on satiety?

Answer 13

L cells

Released in response to high fat and protein

Directly inhibits NPY neurones and activates POMC neurones

Causes satiety and decreased food intake

Question 14

Which peptides/ hormones main satiety?

Answer 14

PYY
GLP-1- glucagon like peptide
PP- pancreatic polypeptide 
OXM- Oxontymodulin
 Melanocyte-stimulating hormones
Cocaine and amphetamine regulated transcript peptides
Leptin 
insulin 

Corticotropin-releasing hormone

Question 15

Which neurones does insulin inhibit and activate to induce satiety signals?

Answer 15

Insulin inhibits NPY/AgRP neurones

Insulin activates αMSH/CART

Question 16

What is the most powerful known incretin (mimics insulin)

Answer 16

Glucagon Like Peptide (GLP)-1

Question 17

How do GLP-1 levels change in obese individuals?

Answer 17

It decreases

Question 18

Where is Cholecystokinin (CCK) synthesised. What is it released in response to?

Answer 18

in duodenum; released in response to fat and protein

Question 19

What are the effects caused by too much CCK?

Answer 19

Nausea and taste aversion-

Question 20

What is Pancreatic polypeptide (PP)

released in response to?

Answer 20

Released in response to food intake, proportional to calories

Question 21

Which molecule is Oxontymodulin
a product of?
Which hormone does it decrease?

Answer 21

preproglucagon

Decreases Ghrelin hormone

Question 22

Will inhibiting ghrelin reduce food intake?

Answer 22

Probably not - In obese subjects, ghrelin is low

reducing it further may not have a large therapeutic effect

Question 23

Which peptides/ hormones main hunger?

Answer 23

Ghrelin
Neuropeptide Y
Agouti-related peptide
Melanin concentrating hormone 
Galanin

Question 24

Which hormone is a melanocortin receptor antagonist?

Answer 24

AGRP

Question 25

Which condition do people with a POMC-deficiency develop?

Answer 25

Hyperphagia and obesity

Question 26

What is released by POMC which reduces food intake?

Answer 26

melanocortins the main one being α-melanocyte-stimulating hormone (α-MSH)

Question 27

What effect does Malonyl CoA have on appetite?

Answer 27

Increased malonyl-coA supresses food intake

Decreased malonyl coA increases food intake

Question 28

The transfer of Fatty acids into the mitochondria is inhibited by what?

Answer 28

malonyl co-A

Question 29

What effect does serotonin have on the appetite? How does serotonin exert these effects?

Answer 29

it is an anorexigen

inhibits food intake

If depleted promotes weight gain

Serotonin receptors increase signalling (simulate) activity in the POMC neurones

They decrease signalling in the AgRP neurones

Question 30

Which serotonin receptor antagonist drug is Moderately effective as weight loss treatment?

Answer 30

Lorcaserin