Flashcards in Principles of Neuroscience Lecture 18 Body Weight Homeostasis Deck (17)
Which regions in the brain are important in body weight homeostasis?
Ventromedial hypothalamus, Arcuate nucleus
Para ventricular nucleus
What are the two types of neuron in the arcuate nucleus?
What is the basic function of each?
Which peptides do the AgRP/NPY neurons make?
AgRP and NPY
Which peptides do the POMC neurons make?
Which other neurons do the AgRP/NPY connect to?
Describe how it affects these neurons
1. To the second order nucleus in the lateral hypothalamus
In signals to these neurons such that it stimulates feeding behaviour and reduction in energy expenditure
2. It connects to the POMC neurons, inhibiting their action
Describe the function of the POMC neurons
These neurons project their axons up to second order neurons in the lateral hypothalamus
They release alpha-MSH onto the MC3/4 receptors
This stimulates inhibition of feeding behaviour and increased energy expenditure
What compounds activate the POMC neurons?
Which compounds inhibit the AgRP/NPY?
What hormones increase energy expenditure, and which decrease it?
Decrease: AgRP and NPY
Describe which compounds bind to MC4 receptors, and how the responses differ
1. Alpha-MSH bind to the receptor and have a signal transduction pathway
2. AgRP binds to the receptor and blocks a-MSH from binding
Describe the role of the para ventricular nucleus in weight homeostasis
This nucleus brings about the release of hormones (eg. TSH) that bring about increase in energy expenditure.
a-MSH stimulates it, to increase energy expenditure
AgRP and NPY inhibit it to decrease energy expenditure
What does mutation in leptin cause?
Obesity, since we have no signalling to reduce feeding behaviour and increase energy expenditure
Describe the rat parabiosis experiment
When a leptin mutant and normal mouse have their circulation connected, the obese mouse's weight will regulate, because the leptin from the normal mouse is now circulating in him and energy expenditure is increased via the para ventricular nucleus
Where is leptin produced?
In the adipose tissue
Describe the function of leptin
It stimulates the release of a-MSH from POMC neurons
It inhibits AgRP and NPY release from the other neurons
Lesions of lateral hypothalamus ...