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Metabolism CC > Appetite Regulation > Flashcards

Appetite Regulation Flashcards

1
Q

Orexigen

A

Substance that increases food intake
–> appetite stimulant
Activates specific neurological pathways to increase hunger/food intake

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2
Q

Orexigen forms

A

Hormones (neuropeptide)
Drugs
Unwanted side effect of medication (increased weight gain)
Desirable outcome of medical therapy (Cachexia treatment, AIDS/cancer)

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3
Q

Anorexigen

A

Substance that inhibits food intake

–> appetite inhibiting

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4
Q

How food broken down in GI

A 
Mastication
Stomach acid
Proteases
Rhythmic gastric contractions
Ingested nutrients pass into duodenum - bile acids, pancreatic enzymes
Nutrients sensed by receptors in GI
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5
Q

Mechanical breakdown location

A

Chewing (mouth)
Churning (stomach)
Segmentation (SI)

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6
Q

Propulsion location

A

Swallowing (oropharynx)

Peristalsis (oesophagus, stomach, SI, LI)

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7
Q

Digestion locations

A

Stomach (end)

SI

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8
Q

Absorption location

A

SI
LI
Into blood vessels + lymph vessels

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9
Q

Enteroendocrine cells

A 
Sense luminal environment
Microvilli "taste" nutrient environment
Vesicles for endocrine hormone release
Specialized cells of the GI tract and pancreas with endocrine function
Release peptides + GI hormones
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10
Q

Enteroendocrine cell activation

A

Nutrients activate GPCR receptors
Release signalling molecules
Vagal Afferent excitation

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11
Q

Vagus nerve appetite regulation

A

Chemoreceptors on vagus nerve activated by mediator released by EEC
Mechanoreceptors stimulated by stretch- gastric distension causes satiety, meal size
Involved in short term (homeostatic) control of appetite

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12
Q

Arcuate nucleus

A

Has reciprocal connections with dorsal vagal complex

Nucleus of tractus solitarius, dorsal motor nucleus of vagus, area postrema

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13
Q

Leptin

A

Satiety factor
Hormone made by adipose tissue- adipokine
Diurnal secretion- not related to food intake

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14
Q

Leptin MOA

A 
Affects organs throughout body
Satiety signal
--> inhibits NPY/AgRP neurones
--> activates POMC/CART neurones
Doesn't respond over short term but long term
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15
Q

Leptin functions throughout body

A 
Helps regulate thyroid hormone synthesis
Decreases glucose-stimulated insulin secretion
Increases HR
Regulates bone mass
Regulates menstrual cycle
Regulates appetite
Activation of immune cells
Increases BP
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16
Q

Leptin + obesity

A

Not treatment for obesity
Circulating leptin levels correlated with body fat- adipose tissue produces leptin at constant rate
Obese individuals have high leptin signals –> said to have leptin resistance
Can be due to loss of function mutations in severe obesity

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17
Q

Leptin as treatment

A

Congenitally leptin deficient children–> leptin injections

Not in diet induced obesity

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18
Q

Defective leptin

A

ob gene

can’t produce effective leptin

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19
Q

Defective receptor

A

db gene

can’t detect leptin

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20
Q

Cholecystokinin (CCK)

A

Anorexigenic
Synthesised in duodenum
Released in response to fat + protein
Slows gastric emptying, releases bile + pancreatic enzymes
Feelings of satiety –> activates vagus nerve

21
Q

PYY 3-36

A 
Anorexigenic
Released from L cells in GI tract
Released in response to high fat/protein
Inhibits NPY neurones
Activates POMC neurones
Decrease food intake
22
Q

Insulin

A

Acute satiety signal
Inhibits NPY/AgRP neurones
Activates alpha MSH/CART

23
Q

GLP1

A

Most powerful incretin
Released in response to food intake
–>decreases blood glucose + food intake
Levels reduced in obese subjects

24
Q

Pancreatic polypeptide

A

Released in response to food intake
Proportional to calories
Decreased appetite
Long term energy balance

25
Q

Oxontymodulin

A

Anorectic peptide product of preproglucagon

Decreases ghrelin levels in plasma

26
Q

Ghrelin

A

Major orexigenic
Predominantly synthesised in stomach
Inhibited by food intake

27
Q

Ghrelin MOA

A

Glucose homeostasis, gut motility, pancreas function, inflammation
Act directly in hypothalamus via vagus

28
Q

Ghrelin receptors

A

Present in brainstem + mesolimbic dopaminergic system

29
Q

Ghrelin short + long term

A

Meal initiator
Chronic administration –> hyperphagia
Obesity- malignant ghrelinoma

30
Q

Ghrelin in obese subjects

A

Low

Reducing it further may not help

31
Q

Hypothalamus

A

Below thalamus

Links NS to endocrine system through pituitary gland

32
Q

Hypothalamus neuroendocrine function

A

Direct neuronal connection to anterior pituitary

Hypophyseal portal system

33
Q

Food intake control

A

Lateral part of ventromedial nucleus of hypothalamus

–> arcuate nucleus

34
Q

Neuropeptide Y (NPY) and Agouti related peptide (agRP)

A

Orexigens

Neuroendocrine neurones

35
Q

Cocaine and Amphetamine related transcript (CART) and pro-opiomelanocortin (POMC)

A

Anorexigens

Neuroendocrine neurones

36
Q

Central orexigenic pathway

A

AGRP/NPY neurones in arcuate nucleus of hypothalamus
Activated by ghrelin
Inhibited by insulin + leptin
Releases NPY –> activates Y1 receptors (increase food intake by activating 2nd order neurones, inhibit POMC/CART neurones)

37
Q

AgRP

A

Melanocortin receptor antagonist

38
Q

Central Anorexigenic pathway

A

POMC/CART neurones in arcuate nucleus of hypothalamus
Activated by insulin + leptin
Decrease food intake by releasing melanocortins

39
Q

Main melanocortin

A

Alpha-melanocyte-stimulating hormone

  • -> Activating second order neurones (MCR4 receptors)
  • -> inhibits NYY/AgRP neurones (MCR3 receptors)
40
Q

Malonyl CoA in hypothalamus

A

Increased malonyl-CoA –> suppresses food intake

Decreased malonyl-CoA –> increases food intake

41
Q

Malonyl-CoA hypothalamus determined by

A

AMP/ATP ratio (energy levels)

AMPK CPT1c relays the signal

42
Q

Serotonin (5HT)

A

Anorexigenic
Increase inhibits food intake
Depletion promotes weight gain

43
Q

5HT2cR receptor

A

Increase signalling activity in POMC neurones

44
Q

5HT1bR receptor

A

Decrease signalling in AgRP neurones

45
Q

Lorcaserin (Belviq)

A

5HT2c receptor agonist

Moderately effective as weight loss treatment

46
Q

Antidepressants

A

can cause weight gain and loss

47
Q

GLP1 agonists

A

Type 2 diabetes

no clear effect on weight loss

48
Q

Regulating appetite strategies

A

PYY synthetic analogue
Vagal nerve stimulation
Enhanced release of GLP1 and PYY

Metabolism CC (29 decks)

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