Eating disorders 2

Question 1

POMC & nicotine

Answer 1

Nicotine activates POMC leading to a decrease in food intake

Question 2

MC4R

Answer 2

Heterozygous mutations in MC4R are the most common cause of obesity in humans.
It causes hyperphagia and decreased satiety

Question 3

Food intake through hormones

Answer 3

AgRP/NPY neurons increase hunger and activate pathways that stimulate food intake
POMC neurons decrease hunger and help promote feelings of fullness
MC4R is involved in the final response of these signals. = When AgRP is active MC4R is inhibited increasing hunger. When POMC neurons are active they activate MC4R, contributing to feelings of satiety or fullness

Question 4

Constitutive Activity

Answer 4

This means that that the MC4R is active even without POMC to activate it. This means that MC4R is constantly active leading to obesity or metabolic disorders

Question 5

Polygenic

Answer 5

Environmental influence

Question 6

Monogenic

Answer 6

Leptin
Melanocortin (MC4R)

Question 7

Reward Circuitry

Answer 7

Anticipatory phase of feeding - dopamine - wanting

Hedonic aspects of the consummatory act - opioids - liking

The change in dopamine is capable of being reversed if the diet is changed

Question 8

Opioids and food

Answer 8

• The striatum contains the (endogenous) opioid peptides enkephalin and β-endorphin and
  is rich in opioid receptors
• Blocking these opioid receptors decreases food intake and in humans it is reported that it
  reduces the pleasantness of food

Question 9

long term signals

Answer 9

White adipose tissue - are informative about energy stores

Question 10

Short term signals

Answer 10

Stomach/intestine - informative about current energy uptake

Question 11

Hormones that influence eating

Answer 11

• Ghrelin
• Cholecystokinin (CCK)
• Glucagon-like peptide (GLP1)
• Peptide YY (PYY)
• Insulin
• Leptin

Question 12

Homeostatic system

Answer 12

Brain stem and the hypothalamus
Integrates peripheral metabolic
markers to affect subjective states
of hunger, satiety, autonomic
nervous activity

Question 13

Reward system

Answer 13

Mesolimbic circuit
Striatum

Registers the reward value associated with food and is involved in the motivation to eat

Question 14

Self-regulation system

Answer 14

Prefrontal and associated cortices

Contextualises appetite with life-goals, values and meaning

Question 15

Hypothalamus

Answer 15

Maintains homeostasis and controls feeding behaviour and metabolism
* Within the ARC two neuronal populations are located with NPY/AgRP neurons
that when stimulated increase feeding, and POMC neurons when stimulated
reduce feeding. These neurons have leptin receptors mediating leptin’s effect
on feeding behaviour
* The ARC densely projects to the PVN and LHA
* The VMH is also important for feeding behaviour, although more for
anticipating food and it senses glucose to direct behaviour

Question 16

Striatum

Answer 16

• The striatum is important for the motivational and rewarding aspect of food
• Dopamine drives the ‘wanting’ and opioids drive the ‘liking’
• Extracellular dopamine increases upon rewarding substances (also sucrose)
• Dopamine 2 receptor binding is decreased in people with obesity
• Blocking opioid receptors decreases food intake and the liking of food

Question 17

Obesity prevention

Answer 17

Nutrition, exercise, diet, drugs, bariatric surgery

Question 18

Bariatric surgery

Answer 18

+ body weight regulation, altered food preference, glycemic control

• Mechanisms not fully understood
  Loss of bone mass density
  Calcium deficiency
  Vitamin D deficiency
  Expensive
  Risk of surgery

Question 19

Pharmacological treatments

Answer 19

Semaglutide - GLP1-agonist = helps with the release of insulin
Naltrexon - mu-opioid-antagonist
Bupropion - noradrenalin and dopamine reuptake inhibitor
Orlistat - Reduces the absorption of dietary fat