Principles of Neuroscience Lecture 18 Body Weight Homeostasis

Question 0

What are the two types of neuron in the arcuate nucleus?

What is the basic function of each?

Answer 0

POMC neurons

AgRP/NPY neurons

Question 1

Which regions in the brain are important in body weight homeostasis?

Answer 1

Lateral hypothalamus
Ventromedial hypothalamus, Arcuate nucleus
Adipose tissue
Para ventricular nucleus

Question 2

Which peptides do the AgRP/NPY neurons make?

Answer 2

AgRP and NPY

Question 3

Which peptides do the POMC neurons make?

Answer 3

alpha MSH

Question 4

Which other neurons do the AgRP/NPY connect to?

Describe how it affects these neurons

Answer 4

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

Question 5

Describe the function of the POMC neurons

Answer 5

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

Question 6

What compounds activate the POMC neurons?

Answer 6

Leptin
Insulin
Nutrients

Question 7

Which compounds inhibit the AgRP/NPY?

Answer 7

Leptin
Insulin
Insulin

Question 8

What hormones increase energy expenditure, and which decrease it?

Answer 8

Increase: alpha-MSH
Decrease: AgRP and NPY

Question 9

Describe which compounds bind to MC4 receptors, and how the responses differ

Answer 9

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

Question 10

Describe the role of the para ventricular nucleus in weight homeostasis

Answer 10

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

Question 11

What does mutation in leptin cause?

Answer 11

Obesity, since we have no signalling to reduce feeding behaviour and increase energy expenditure

Question 12

Describe the rat parabiosis experiment

Answer 12

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

Question 13

Where is leptin produced?

Answer 13

In the adipose tissue

Question 14

Describe the function of leptin

Answer 14

It stimulates the release of a-MSH from POMC neurons

It inhibits AgRP and NPY release from the other neurons

Question 15

Lesions of lateral hypothalamus …

Answer 15

Thin

Question 16

Lesions of Ventromedial hypothalamus

Answer 16

Overweight