Appetite regulation

Question 1

Define Adiposity

Answer 1

Level of body fat

Question 2

What is an Adipostat?

Answer 2

Produced by adipose tissue; circulating levels are proportional to body fat

Question 3

Give 2 examples of an adipostat

Answer 3

Leptin

Insulin

Question 4

Name 3 areas of the hypothalamus related to hunger regulation

Answer 4

Ventromedial
Lateral
Arcuate nucleus

Question 5

Which area of the brain is responsible for appetite regulation?

Answer 5

Hypothalamus

Question 6

What is meant by the ‘set point’ of body weight?

Answer 6

With unlimited & free choice of food an animal’s body weight will be defended about a set point.
Starvation causes weight loss
Force feeding causes weight gain

Question 7

Which areas of the hypothalamus are affected directly by blood glucose levels?

Answer 7

Ventromedial

Lateral

Question 8

An increase in blood glucose;
Will turn on which area of hypothalamus?
To have what effect?

Answer 8

Ventromedial

Satiety

Question 9

A decrease in blood glucose;
Will turn on which area of hypothalamus?
To have what effect?

Answer 9

Lateral

Hunger

Question 10

A mouse with Ventromedial HT lesion.

What will happen to body weight and set point?

Answer 10

Weight gain

Increased set point

Question 11

A mouse with Lateral HT lesion.

What will happen to body weight and set point?

Answer 11

Weight loss

Decreased set point

Question 12

Leptin is encoded for by which gene?

Answer 12

Ob gene

Question 13

On which area of the hypothalamus does Leptin act primarily?

Answer 13

Arcuate nucleus

Question 14

What changes would be expected following a decrease in Leptin levels?
(after weight loss)

Answer 14

Increased food intake
Decreased temperature
Decreased energy expenditure
Decreased reproductive function
Increased parasympathetic activity (rest & digest)

Question 15

What changes would be expected following an increase in Leptin levels?
(after weight gain)

Answer 15

Lower food intake
Lower energy expenditure
Increased sympathetic activity

Question 16

What type of peptides are released from the Arcuate Nucleus in response to high Leptin levels?

Answer 16

Anorexigenic peptides

ee. CART, aMSH

Question 17

What is an anorexigenic?

Answer 17

Peptide that inhibits feeding behaviour

Question 18

Give 2 examples of anorexigenic peptides

Answer 18

aMSH
(alpha-melanocyte stimulating hormone), secreted by the POMC nuclei of the Arcuate nucleus.

CART
(Cocaine and amphetamine related transcript)

Question 19

What area of the HT do Orexigenic peptides act on?

Answer 19

Lateral hypothalamus

Question 20

Are Orexigenic peptide release a response to increased or decreased Leptin levels?

Answer 20

Decreased Leptin levels

Question 21

Name 2 Orexigenic peptides

Answer 21

NPY
(Neuropeptide Y)

AgRP
(Agouti-related peptide)

Question 22

What effect do Orexigenic peptides have on feeding behaviour?

Answer 22

They activate feeding behaviour

Question 23

What effects do aMSH and AgRP have on the Melanocortin Receptor?
MCR4

Answer 23

aMSH activates the receptor

AgRP blocks the receptor

Question 24

What is the most common cause of inherited obesity?

Answer 24

MCR4 mutation

Present in 1-2.5% of obese people

Question 25

What effect does leptin treatment have on a person with congenital leptin deficiency?

Answer 25

Effective form of treatment | Causes weight loss

Question 26

What effect does leptin treatment have on most overweight people?

Answer 26

No effect | Majority of obese people have normal leptin genes; they commonly have high circulating leptin levels

Question 27

What hormone signals hunger?

Answer 27

Ghrelin

Question 28

Where is Ghrelin produced, and how is it regulated?

Answer 28

Stomach | Regulated by calorie intake

Question 29

Where does Ghrelin act?

Answer 29

Arcuate nucleus of HT

Question 30

What happens to Ghrelin levels in obesity?

Answer 30

Ghrelin levels are reduced Targetting the Ghrelin pathway to treat obesity has been ineffective. Ghrelin levels are low at the appropriate times in obesity

Question 31

Which nerve signals satiety?

Answer 31

Vagus

Question 32

What activates the Vagus nerve to signal satiety?

Answer 32

Stomach distension | CCK; relesed by gut epithelia in response to fatty meal

Question 33

What area of the HT produces orexigenic and anorexigenic peptides?

Answer 33

Arcuate nucleus

Question 34

What area of the brain does the Vagus nerve stimulate in response to being full?

Answer 34

Nucleus of the solitary tract | Which comuunicates with the HT

Question 35

What happens to serotonin levels during appetite

Answer 35

Serotonin levels are increased in anticipation of a meal and peak during a meal, especially if carb rich

Question 36

Name a drug that promotes satiety

Answer 36

Sibutramine (reductil)

Question 37

How does Sibutramine work?

Answer 37

Serotonin and Noradrenaline reuptake inhibitor Increases satiety & reduces metabolic supression that occurs with weight loss Withdrawn, CV risks

Question 38

What is the reward hormone?

Answer 38

Dopamine

Question 39

From where is dopamine released?

Answer 39

VTA; ventral tegmental area

Question 40

How does the Dopaminergic reward system affect appetite?

Answer 40

Causes consumption of palatable foods.

Question 41

How do endocanabinoids cause hunger?

Answer 41

Released post-synaptically Block volt-gated Ca2+ channels Prevent neurotransmitter release