Week 8: Appetite regulation Flashcards
Why has obesity and diabetes become so prevalent?
Portion size has increased
We stopped moving
Generated a positive energy balance
Why is the decision to eat food so complex?
Psychological and environmental factors
Initiation/termination of meals, size, composition, frequency
Lifestyle habits, drive to seek tasty foods, enjoyment, social
Steps involved in the physiology of energy intake
1) Afferent peripheral hormone signalling
2) Central integration
3) Efferent signalling
4) Behavioural change
Episodic signals
Short term (meal-meal)
ex. gastrointestinal and exercise
Tonic signals
Long-term (days and weeks)
ex. body composition and exercise
2 different afferent peripheral hormone signals
- Appetite stimulating (orexigenic)
- Satiety stimulating (anorexigenic)
What organs are involved in energy intake?
Stomach
Intestine
Pancreas
Adipose tissue
Orexigenic neurohormone
Ghrelin
Anorexigenic neurohormones
PYY
GLP-1
Leptin
CCK
Insulin
What neurohromone is secreted by the stomach?
Ghrelin
(must be acylated)
What neurohormones are secreted from the intestine?
PYY (peptide YY)
GLP-1 (glucagon-like peptide)
CCK
What neurohormones are secreted from the pancreas?
PP (pancreatic polypeptide)
What neurohormone is secreted by adipose tissue?
Leptin
Orexigenic neuropeptides
NPY (neuropeptide Y)
AgRP (agouti-related peptide)
Anorexigenic neuropeptides
POMC (pro-opiomelanocortin) which is quickly converted to alpha-melanocyte stimulating hormone
CART (cocaine-amphetamine regulated transcript)
Arcuate nucleus
Integrates peripheral signals from neurohormones which generates a response that can eventually generate a behavioural action
*generates release of neuropeptides
Role of the vagus nerve in energy intake
Important source of indirect neuronal stimulation
Composed of efferent/afferent sensory fibres
May be directly involved with CNS or indirectly involved with peripheral peptides
Low intensity continuous exercise
<50% VO2 max
Moderate intensity continuous exercise (MICT)
50-70% VO2 max
High intensity continuous exercise (HICT)
> 70% of VO2 max
Study 1 results IL-6 and lactate
Exercise generates an increase in IL-6, especially at higher intensities
SIT results in the largest increase in lactate
Study 1 results ghrelin and hunger
More ghrelin 90 min after MICT session compared to control
SIT resulted in ghrelin being at the same level as it was prior to exercise
VICT and SIT not as hungry immediately following exercise
Study 1 results- energy intake
On day of exercise intervention the SIT group ate less
Day after exercise intervention VICT and SIT ate less
Study 2 results
Bicarbonate group had more lactate and a reduction in ghrelin and a lower appetite
Study 3- results
Obese individuals have higher IL-6 and less ghrelin, PYY and GLP-1 than lean individuals
Study 4- results
After exercise in the follicular phase there is a greater reduction in ghrelin
What is adipose tissue a depot for?
Energetic errors- more energy we consume goes to fat tissue
- but the type of exercise you do can help
What is the role of tryptophan in hunger regulation?
Essential amino acid, precursor for serotonin production
Increases dopamine
What is the role of endocannabinoids in hunger regulation?
Activates PYY and GLP-1
What is the role of short chain fatty acids in hunger regulation?
Activates GLP-1
Activates AgRP/NPY
