Appetite Regulation Flashcards
3 ways appetite is regulated
1) Hormones involved in regulating appetite
2) Appetite regulation centers
3) Appetite regulation signalling to peripheral tissues
4 Hormones invovled in regulating appetite
Hormones invovled in regulating appetite
Leptin is coded by
the lep gene
Leptin is secreted from
1)White adipose tissue (WAT)
2) stomach (gastric secretion)
Brown adipose tissue is for
thermogenesis (uncoupling of the oxidative phosphorylation by UCP1: Lecture 7)
Plasma levels [blank] as amount of adipose tissue [blanks]
Increases x2
Adipose tissue role
Regulates body weight by signalling to the brain the amount of energy stored as fats in adipocytes
What is LEPR
Leptin receptor
Where is the leptin receptor found
hypothalamus
Binding to LEPR leads to what 2 effects
1)Decrease in activity of NPY/AgRP neurons
2) Increase in activity of POMC/CART neurons
What happens in mice that are LEP -
Mice become obese and suffer from hyperphagia (abnormal increase in appetite)
What happens in mice that are LEP -
Mice become obese and suffer from hyperphagia (abnormal increase in appetite)
Explain why obesity leads to leptin resistance
Lean and obese individuals were given:
1) A meal high in carbohydrates.
2) A meal high in fat
3) or were subjected to a fasting period
-Concentration of leptin in the blood was analyzed.
Hyperleptinaemia was observed because it was shown to be associated with a decrease in Insulin production and also an increase in insulin resistance. Leading to type 2 diabetes. (stop responding to leptin because there is too much in obese people)
Insulin is secreted by
β-cells of the pancreas in response to high blood glucose.
In context of appetite regulation where are insulin receptors found
hypothalamus
What does insulin bind to and what are the effects
1) Decrease in activity of NPY/AgRP neurons
2) Increase in activity of POMC/CART neurons
Which cause a decrease in appetite
Where does PYY3-36 of the gastroinstestinal tract originate form
Peptide YY (36AA) is cleaved to give PYY3-36
PYY3-36 is released from the gut in a [blank] and explain
nutrient dependent manner
Explain:
1) During fasting, low level of PYY3-36 can be found in the blood
2) It reaches a peak of blood concentration at 1-2 hours after a meal.
3) Stays in circulation for several hours
What does PYY3-36 bind to and its effects
PYY3-36 binds to Y-receptors located on NPY/AgRP neurons (mainly Y2R).
Binding of PYY3-36 to its receptors leads to decrease in activity of NPY/AgRP neurons causing decrease in appetite
What does PYY3-36 bind to and its effects
PYY3-36 binds to Y-receptors located on NPY/AgRP neurons (mainly Y2R).
Binding of PYY3-36 to its receptors leads to decrease in activity of NPY/AgRP neurons causing decrease in appetite
Ghrelin
Hunger hormone
Ghrelin is produced by
specialized cells of the gastrointestinal tract
Ghrelin is released from [blank] and when
The stomach when empty
When is ghrelin not secreted
Following a meal, stretching of the stomach (and multiple other signals) stops the secretion of ghrelin
What is ghrelins receptor and where is it found and its function
Receptor: ghrelin/growth hormone secretagogue receptor (GHSR)
Where: NPY/AgRP neurons
Function: Increase activity of NPY/AgRP neurons to increase appetitie
T or F: The hypothalamus is an appetite regulation center
True
What does the hypothalamus do in appetite regulation
Critical in regulation of food intake containing neural circuits, which produces a number of peptides that influence food intake.
The hypothalamus is a cluster of interconnected nucleus, but what is one nucleus involved in appetite regulation and why
Arcuate nucleus (ARC) is composed of two different populations of neurons:
1) Neurons expressing orexigenic neuropeptides
-Neuropeptide Y (NPY)
-Agouti-related peptide (AgRP)
2) Neurons expressing anorexigenic neuropeptides
-Pro-opiomelanocortine (POMC)
-Cocaine-amphétamine related transcript (CART)
What does orexigeneic signals do
Neuropeptide stimulating appetite that leads to an increase in food intake
What does anorexigenic signalling do
Neuropeptide causing a loss of appetite that leads to a decrease in food intake
What 4 organs and their secreted circulating factors that effect food intake and how
1) Pancreas: Insulin
2) Adipose tissue: Leptin
3) Stomach and intestine: Ghrelin and PYY3-36
HOW: These molecules mediate their effects by signalling to the arcuate nucleus neurons.
Pareventricular nucleus (PVN) is a [blank] and receives information from [blanks]
Integration center and receives information from NPY/AgRP and POMC/CART arcuate nucleus neurons
What two anorexigenic substances (hormones) are secreted from PVN projections
1) Thyrotropin-releasing hormone (TRH)
2) Corticotropin-releasing hormone (CRH)
What two anorexigenic substances (hormones) are secreted from PVN projections
1) Thyrotropin-releasing hormone (TRH)
2) Corticotropin-releasing hormone (CRH)
Lateral hypothalamic area receives information from
Projections from NPY/AgRP and POMC/CART arcuate nucleus neurons
What 2 orexigenic substances are secreted from LHA projections
1) Orexin-A
2) Orexin-B
What 2 orexigenic substances are secreted from LHA projections
1) Orexin-A
2) Orexin-B
Summary of the arcuate nuclues and its neurons
1) Arcuate nucleus (ARC) contains anorexigenic and orexigenic first-order neurons.
2) Projections from ARC neurons are connected to second-order neurons located in PVN and LHA leading to anorexigenic and orexigenic responses.
List of appetite neurotransmitters and their effects
Appetite neurontransmitters work where
in between the nucleus’s
Neuropetide Y (NPY)
Known as the strongest orexigenic molecule and diminishes the energy expenditure of the body.
What controls the synthesis and release of neuropeptide Y (NPY)
Inhibited by leptin and insulin
Activated by ghrelin
Function of the agouti gene
to control the differential production of melanin pigments in the skin that gives rise to the true wild-type coat color of mice.
What is one of the best describe agouti mutations and a special name for it
1) gaouti mutation are the lethal yellow (AY) and viable yellow (AVY) mutations.
2) For both mutations, a portion of the agouti promoter is deleted and the consequence of this deletion is a strong and ubiquitous expression of agouti from another promoter located upstream.
The phenotype of these mutations is also known as the yellow obese syndrome.
What is the link between agouti and AgRP
AgRP and agouti are coded by different genes but they are 25% identical.
Where does agouti affect in terms of appetite
Pro-opiomelanocortin (POMC)
Endogenous ligand for the melanocortin-4 receptor (MCR4) and is also a precursor for other hypothalamus neurotransmitters
MCR4 (POMC) is located on
PVN neurons
POMC signalling leads to
an anorexigenic response (Decrease in appetite).
Mice lacking POMC and its receptor causes what
obesity
Fatty acid synthase (FAS) and ACetyl-CoA carboxylase are strongly expressed where (Roles of malonyl-CoA and LCFAs in appetite control)
In the ARC of the hypothalamus
Increased levels of malonyl-Coa could act as (Roles of malonyl-CoA and LCFAs in appetite control)
anorexigenic singals
Injection of long chain fatty acids does what (Roles of malonyl-CoA and LCFAs in appetite control)
Inhibits food intake
Inhibition of fatty acid synthase was shown to cause (Roles of malonyl-CoA and LCFAs in appetite control)
Weight loss through accumulation of malonyl CoA
-Was shown in obese mice C75 in image
Inhibition of fatty acid synthase was shown to cause (Roles of malonyl-CoA and LCFAs in appetite control)
Weight loss through accumulation of malonyl CoA
-Was shown in obese mice C75 in image
How malonyl coa effects other parts of metabolism
How malonyl coa effects other parts of metabolism
Why are celebrities taking a T2D durg to lose weight
Drug: Semaglutide (Ozempic, Wegovy and Rybelsus)
It is a GLP-1 receptor agonist that mimics GLP-1 to increase insulin secretion and insulin sensitivity. It also found to reduce food intake through a decrease in appetite and slow down of digestion the stomach.
15-30%
Is it a good idea to get a prescription of semaglutide to lose weight?
As of now, no, because you are taking away a drug from somebody who need it to control a medical condition (T2D) and there is currently a shortage of this drug in some countries (Australia).
**Not approved for weight loss in Canada.
Possible side effects include: nausea, diarrhea, vomiting, constipation, abdominal pain, headache, fatigue, indigestion/heartburn, dizziness, bloating (abdominal distension), belching, low blood sugar (hypoglycemia) in patients with type 2 diabetes, gas (flatulence), gastroenteritis, and gastroesophageal reflux disease (GERD)
