Appetite Regulation Flashcards
Orexigen
Substance that increases food intake
Anorexigen
Substance that inhibits food intake
What cell types sense nutrients in the gut lumen
Enteroendocrine cells
What structures do Enteroendocrine cells use to sense nutrients in the gut lumen
Microvilli
What feature of Enteroendocrine cells allows them to communicate with neurones and blood vessels
Contain vesicles for hormone release
What causes receptor activation on Enteroendocrine cells
Nutrients
What do mediators released by enteroendocrine cells activate
Chemoreceptors on vagal afferents
What type of receptors detect gastric distension
Stretch stimulated Mechanoreceptors
Is response to stomach distension a long or short term form of appetite control
Short
Which nucleus is involved in appetite regulation
Arcuate nucleus
What tissue produces adipokines inc leptin
Adipose
What is the pattern of leptin secretion
Diurnal
Does leptin have long or short term effects on appetite
Long term
What does leptin signal
Satiety
Actions of leptin
Inhibits NPY/AgRP Neurones
Activates POMC/CART neurones
Is leptin orexigenic or anorexigenic
Anorexigenic
Why can leptin not be targeted for obesity treatment
Leptin usually already high in obese individuals
When is cholecystokinin released
In response to fat and protein
Where is cholecystokinin synthesised
Duodenum
Is cholecystokinin orexogenic or anorexigenic
Anorexigenic
Effects of cholecystokinin
Slows gastric emptying
Released bile
Releases pancreatic enzymes
Activate vagus nerve to cause satiety
What is caused by too much cholecystokinin release
Nausea
Taste aversion
Is PYY 3-36 anorexigenic or orexigenic
Anorexigenic
When is PYY 3-36 released
In response to high fat or protein
What cells release PYY 3-36
L cells in GI
How does PYY 3-36 cause satiety
Inhibits NPY neurones
Activates POMC neurones
What is the action of PYY 3-36
Increases satiety
Long term negative regulator of body weight
What groups have low PYY 3-36
Overweight
Overweight in past
How does insulin cause satiety
Inhibits NPY/AgRP neurones
Activates alpha MSH/CART
What is the most powerful Incretin
Glucagon like peptide
Incretin
Gut hormones that stimulates insulin release after eating
What causes GLP 1 release
Food intake
What group has decreased GLP 1 level
Obese
What causes release of pancreatic polypeptide
Food intake proportional to calories
Is pancreatic polypeptide orexigenic or anorexigenic
Anorexigenic
Is oxontymodulin anorexigenic or orexigenic
Anorexigenic
Actions of oxontymodulin
Decrease plasma Ghrelin level
Increase energy expenditure
What is the major peripheral orexigenic hormone
Ghrelin
Where is Ghrelin synthesised
Stomach
What inhibits Ghrelin
Food intake - proportional to calories
Does Ghrelin have short or long term effects
Both
Where is Ghrelin found
Circulation in plasma
Where can Ghrelin act
Receptors in brainstem
Receptors in Mesolithic dopaminergic system
Vagus
Directly on hypothalamus
How are Ghrelin levels altered in obesity
Decreased
Why can Ghrelin not be targeted in obesity treatment
Already low in obesity
May affect growth regulation
Prevent beneficial effects of Ghrelin on CV system and inflammation
Orexigenic hormones
Ghrelin
Neuro peptide Y
Agouti related peptide
Orexins
Melanin concentrating hormones
Galanin
Anorexigenic hormones
Leptin
Cholecystokinin
Insulin
Glucagon like peptide
Peptide YY
Oxyntomodulin
Cocaine and amphetamine regulated transcript peptides
Corticotropin releasing hormone
Melanocyte stimulating hormone
What does the hypothalamus influence to regulate metabolic rate
Pituitary function
Feeding
Stress response
Water balance
Sleep wake cycle
Thermoregulation
What are the neural pathways that control food intake
Central orexigenic pathway
Central anorexigenic pathway
Which neurones are involved in the central orexigenic pathway
AGRP/NPY neurones in arcuate nucleus of hypothalamus
Which appetite regulating neural pathway are POMC/CART neurones involved in
Central anorexigenic pathway
What hormone activates the central orexigenic pathway
Ghrelin
How do insulin and leptin effect the central anorexigenic and orexigenic pathways
Inhibits central orexigenic pathway
Activate central anorexigenic pathway
How does malonyl CoA affect food intake
Incr malonyl CoA -> suppress food intake
Decr malonyl CoA -> increase food intake
What process is malonyl CoA the first step in
De novo fatty acid synthesis
What determines malonyl CoA
AMP/ATP ratio
Is serotonin anorexigenic or orexigenic
Anorexigenic
How does serotonin cause effects on appetite
Stimulate POMC neurone activity
Inhibit AgRP neurone activity
How do antidepressants affect weight
Can cause loss or gain
How do cannabinoids effect food intake
Increase
2 Endogenous cannabinoids
Anandamide
2 arachadonylglycerol
What appetite control based drugs are recommended by NICE for obesity treatment
None
Current obesity treatments
Lifestyle/behaviour changes
Fat absorption inhibition - orlistat
Bariatric surgery