Lecture 31 - Feeding and Weight Control Flashcards Preview

Frontiers in Biomedicine > Lecture 31 - Feeding and Weight Control > Flashcards

Flashcards in Lecture 31 - Feeding and Weight Control Deck (58):
1

Peripheral signals involved in weight control
1)
2)
3)

1) CCK
2) Leptin
3) Ghrelin

2

Hypothalamic chemicals involved in weight control
1)
2)
3)

1) Neuropeptide Y
2) POMC
3) Agouti-related peptide

3

Adiposity signals

Leptin
Insulin
Act long-term

4

Peptides that increase food intake
1)
2)
3)
4)
5)
6)

1) Neuropeptide Y
2) Melanin concentrating hormone
3) Agouti-related peptide
4) Orexin A and B
5) Endocannabinoids
6) Ghrelin

5

Peptides that increase food intake that act in the brain
1)
2)
3)
4)
5)

1) Neuropeptide Y
2) Melanin concentrating hormone
3) Agouti-related hormone
4) Orexin A and B
5) Endocannabinoids

6

Peptides that increase food intake that act in the periphery

Ghrelin

7

Peptides that decrease food intake
1)
2)
3)
4)

1) a-melanocyte stimulating hormone
2) CART
3) Leptin
4) Cholecystokinin

8

Peptides that increase food intake that act on the brain

Alpha-melanocyte stimulating hormone

9

Peptides that increase food intake that act in the periphery

CART
Leptin
Cholecystokinin

10

Where is CCK produced, and in response to what?

Produced by gut
Released in response to digestion of certain nutrients, particularly fat

11

What does CCK act on?

Binds to CCKa receptor on vagus nerve.
This transmits information to nucleus tractus solitarius in medulla.
This transmits to hypothalamus to terminate a meal.

12

How does CCK stimulation of vagus nerve affect the brain?

Ascending signal passes through nucleus tractus solitarius to hypothalamus.
Acts on hypothalamus to terminate a meal.

13

Where is ghrelin secreted?

By stomach

14

When do ghrelin levels rise?

Pre-prandially

15

What are ghrelin plasma levels inversely-proportional to?

BMI

16

Effect of increased ghrelin on appetite

Increases appetite

17

Ghrelin receptor name and locaiton

GHSR-1a, located in hypothalamus

18

Effect of increasing CCK level in rats

More frequent, smaller meals. Not much effect on weight.

19

Does ghrelin quickly or slowly modulate hunger?

Quickly

20

What secretes leptin?

Adipocytes

21

What are plasma leptin levels inversely proportional to?

BMI, adiposity

22

Effect of increased leptin on hunger

Decreases hunger

23

How does leptin enter the brain?

Via transporter across the blood brain barrier

24

Parts of hypothalamus that are involved in hunger

Arcurate nucleus
Paraventricular nucleus

25

Arcurate nucleus role in hunger

Contains cell bodies of neurons that project to paraventricular nucleus

26

Hunger-related neurons in arcurate nucleus
1)
2)

1) POMC/CART neurons. When stimulated, reduce food intake
2) Neuropeptide Y/Agouti-related peptide neurons. When stimulated, increase food intake.

27

Neurons that release factors that increase food intake

Neuropeptide Y/Agouti-related peptide neurons in the arcurate nucleus of the hypothalamus

28

Neurons that release factors that decrease food intake

POMC/CART neurons in the arcurate nucleus of the hypothalamus

29

Effect of leptin on the arcurate nucleus

Stimulates POMC/CART neurons, inhibits NPY/AGRP neurons. This results in reduction of food intake.

30

Members of the pancreatic polypeptide family
1)
2)
3)

1) Neuropeptide Y (synthesised in CNS)
2) Peptide YY (GIT)
3) Pancreatic polypeptide (pancreatic islets)

31

Highly-conserved neuropeptide involved in food intake regulation

Neuropeptide Y

32

NPY effects

1) Potent stimulator of appetite
2) Reduces energy expenditure

33

Where does NPY act?

On the hypothalamus (paraventricular nucleus)

34

NPY receptors
1)
2)
3)

1) All GPCR
2) Y1, Y5 involved in appetite stimulation. Located post-synaptically
3) Y2 is an autoreceptor. Located presynaptically, regulates NPY release

35

What regulates release of NPY?

Leptin

36

POMC

Pro-opiomelanocortin
A precursor protein to several neurotransmitters

37

Important cleavage product of POMC in hunger regulation

Alpha-melanocortin stimulated hormone

38

Release pattern of a-MSH

Tonically-released, therefore tonically inhibits food intake

39

POMC localisation in CNS

Limited to arcurate nucleus and nucleus tractus solitarius.
Colocalised with other neuropeptides in arcurate nucleus

40

What cleaves aMSH from POMC?

Prohormone convertases (PC1 and PC2)

41

POMC receptor

Melanocortin receptors 1 to 5 (MC1-5R).
GPCR

42

aMSH receptor

MC4R.

43

From where is aMSH released?

Paraventricular nucleus

44

Effect of aMSH

Increases energy expenditure

45

What regulates aMSH?

Leptin, feeding status

46

Agouti-related peptide location in CNS

Synthesised in arcurate nucleus.
Co-localised with NPY

47

What does AGRP bind to?

It is an endogenous antagonist of MC4R

48

Endogenous agonist of MC4R

aMSH

49

Endogenous antagonist of MC4R

AGRP

50

Effect of AGRP

Inhibits aMSH by binding to MC4R.
Increases food intake, reduces energy expenditure

51

Effect of decreased leptin expression
1)
2)
3)
4)

1) Decreased leptin action in the hypothalamus
2) Inhibition of POMC neurons, which results in less aMSH
3) Activation of NPY/AGRP neurons in arcurate nucleus. Increased NPY/AGRP release to PVN. AGRP blocks aMSH action.
4) Increased food intake, decreased energy expenditure

52

Effect on hypothalamus of ghrelin

Stimulates AGRP/NPY neurons in arcurate nucleus

53

Adoption studies of BMI

BMI of adopted child closer to biological parents than adoptive parents

54

Major contributing factor to obesity epidemic

Hedonic systems involved in eating palatable food

55

Pathway activated in response to palatable food

Mesolimbic dopaminergic system (the same one that is involved in addiction)

56

Areas involved in hedonic mesolimbic dopaminergic system

Ventral tegmental area and nucleus accumbens

57

Effect of leptin on mesolimbic system

Inhibits activity of VTA dopaminergic neurons, which express leptin receptors

58

Effect of ghrelin on mesolimbic system

VTA neurons have ghrelin receptors.
Stimulates activity of VTA neurons.
Increases reward for eating food.