Lecture 31 - Feeding and Weight Control Flashcards Preview

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

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

A

1) CCK
2) Leptin
3) Ghrelin

2
Q

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

A

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

3
Q

Adiposity signals

A

Leptin
Insulin
Act long-term

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

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

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

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

6
Q

Peptides that increase food intake that act in the periphery

A

Ghrelin

7
Q
Peptides that decrease food intake 
1)
2)
3)
4)
A

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

8
Q

Peptides that increase food intake that act on the brain

A

Alpha-melanocyte stimulating hormone

9
Q

Peptides that increase food intake that act in the periphery

A

CART
Leptin
Cholecystokinin

10
Q

Where is CCK produced, and in response to what?

A

Produced by gut

Released in response to digestion of certain nutrients, particularly fat

11
Q

What does CCK act on?

A

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
Q

How does CCK stimulation of vagus nerve affect the brain?

A

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

13
Q

Where is ghrelin secreted?

A

By stomach

14
Q

When do ghrelin levels rise?

A

Pre-prandially

15
Q

What are ghrelin plasma levels inversely-proportional to?

A

BMI

16
Q

Effect of increased ghrelin on appetite

A

Increases appetite

17
Q

Ghrelin receptor name and locaiton

A

GHSR-1a, located in hypothalamus

18
Q

Effect of increasing CCK level in rats

A

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

19
Q

Does ghrelin quickly or slowly modulate hunger?

A

Quickly

20
Q

What secretes leptin?

A

Adipocytes

21
Q

What are plasma leptin levels inversely proportional to?

A

BMI, adiposity

22
Q

Effect of increased leptin on hunger

A

Decreases hunger

23
Q

How does leptin enter the brain?

A

Via transporter across the blood brain barrier

24
Q

Parts of hypothalamus that are involved in hunger

A

Arcurate nucleus

Paraventricular nucleus

25
Q

Arcurate nucleus role in hunger

A

Contains cell bodies of neurons that project to paraventricular nucleus

26
Q

Hunger-related neurons in arcurate nucleus
1)
2)

A

1) POMC/CART neurons. When stimulated, reduce food intake

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

27
Q

Neurons that release factors that increase food intake

A

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

28
Q

Neurons that release factors that decrease food intake

A

POMC/CART neurons in the arcurate nucleus of the hypothalamus

29
Q

Effect of leptin on the arcurate nucleus

A

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

30
Q

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

A

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

31
Q

Highly-conserved neuropeptide involved in food intake regulation

A

Neuropeptide Y

32
Q

NPY effects

A

1) Potent stimulator of appetite

2) Reduces energy expenditure

33
Q

Where does NPY act?

A

On the hypothalamus (paraventricular nucleus)

34
Q

NPY receptors
1)
2)
3)

A

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

35
Q

What regulates release of NPY?

A

Leptin

36
Q

POMC

A

Pro-opiomelanocortin

A precursor protein to several neurotransmitters

37
Q

Important cleavage product of POMC in hunger regulation

A

Alpha-melanocortin stimulated hormone

38
Q

Release pattern of a-MSH

A

Tonically-released, therefore tonically inhibits food intake

39
Q

POMC localisation in CNS

A

Limited to arcurate nucleus and nucleus tractus solitarius.

Colocalised with other neuropeptides in arcurate nucleus

40
Q

What cleaves aMSH from POMC?

A

Prohormone convertases (PC1 and PC2)

41
Q

POMC receptor

A

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

GPCR

42
Q

aMSH receptor

A

MC4R.

43
Q

From where is aMSH released?

A

Paraventricular nucleus

44
Q

Effect of aMSH

A

Increases energy expenditure

45
Q

What regulates aMSH?

A

Leptin, feeding status

46
Q

Agouti-related peptide location in CNS

A

Synthesised in arcurate nucleus.

Co-localised with NPY

47
Q

What does AGRP bind to?

A

It is an endogenous antagonist of MC4R

48
Q

Endogenous agonist of MC4R

A

aMSH

49
Q

Endogenous antagonist of MC4R

A

AGRP

50
Q

Effect of AGRP

A

Inhibits aMSH by binding to MC4R.

Increases food intake, reduces energy expenditure

51
Q
Effect of decreased leptin expression 
1)
2)
3)
4)
A

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
Q

Effect on hypothalamus of ghrelin

A

Stimulates AGRP/NPY neurons in arcurate nucleus

53
Q

Adoption studies of BMI

A

BMI of adopted child closer to biological parents than adoptive parents

54
Q

Major contributing factor to obesity epidemic

A

Hedonic systems involved in eating palatable food

55
Q

Pathway activated in response to palatable food

A

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

56
Q

Areas involved in hedonic mesolimbic dopaminergic system

A

Ventral tegmental area and nucleus accumbens

57
Q

Effect of leptin on mesolimbic system

A

Inhibits activity of VTA dopaminergic neurons, which express leptin receptors

58
Q

Effect of ghrelin on mesolimbic system

A

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