9. Appetite regulation Flashcards
What is the role of the hypothalamus in feeding?
The urge to eat is controlled primarily within the hypothalamus and it also acts to integrate peripheral satiety signals
Involves a large number of neurotransmitters
Where in the hypothalamus is the main centre for the regulation of appetite?
The arcuate nucleus
What is meant by ‘orexigenic’ and which neurotransmitters are orexigenic?
Appetite stimulating
Neuropeptide Y (NPY)
Agouti related peptide (AgRP)
MCH
What is meant by ‘anorexigenic’ and which neurotransmitters are anorexigenic?
Appetite inhibiting
POMC
CART
Describe the effect of serotonin on the neurotransmitters and the significance of this
Serotonin affects the POMC and the NYC systems - can essentially lead to a decrease in appetite
This signifies that mood can play a role in appetite
What is grehlin and what is it’s role in appetite?
Hormone released from the stomach
High levels of ghrelin leads to a sensation of hunger
Ghrelin receptors are found on NPY neurones - Ghrelin stimulates NPY and so increases food intake - does this directly and also via the vagus nerve
What is the role of GLP-1 on appetite?
Glucagon-like-peptide
Released from the L cells in the gut lining i.e. in the small intestine
Inhibits NYP and stimulates POMC and so acts as an appetite suppressant
What is the effect of PYY and of CCK on appetite?
These hormones both act to suppress appetite
What is leptin?
This is a hormone secreted by the adipose tissue at a constant rate
Leptin causes there to be a decreased release and decreased level of AGRP and so acts as an appetite suppresant
The more leptin that is released, the less hungry you feel
Describe the link between leptin and increased body fat
The more adipose tissue you have, the more leptin you have
SO the fatter you are, the more leptin you produce - this should technically hence suppress your hunger so that you do not eat as much
BUT there is an idea of leptin resistance whereby you can ignore the high levels of leptin so that it ceases to have an appetite suppressing effect - this means that you can continue to eat even when further food intake is not required and hence can lead to increased levels of obesity within the population
What is the effect of insulin on appetite?
Acts in the same way as leptin
When insulin levels are high, causes levels of AGRP to fall and so acts as an appetite suppressant
What is the role of Malonyl CoA on appetite?
Potent controller of appetite
High levels of malonyl coA activates the POMC system and so acts to suppress appetite
How can the levels of malonyl coA be controlled?
Levels of malonyl coA can be controlled by calcium which is regulated by ghrelin
SO malonyl coA is essentially regulated by gut hormones
What else plays a major role in the regulation of appetite?
Gut microbiome - there are different gut microbes present in obese and lean mice
Currently being researched
What therapeutics can be used to increase food intake?
Cannabinoids - these are drugs which increase appetite and the consumption of food
