Lecture 32: Neurocircuitry of Metabolism 4

Question 1

What is the role of white adipose tissue?

Answer 1

only stores energy

Question 2

What is the role of brown adipose tissue?

Answer 2

stores energy for the purpose of expending this energy using the protein UCP-1

Question 3

What do sympathetic neurons that innervate beige / brown adipocytes contain?

Answer 3

tyrosine hydroxylase (TH)

Question 4

What do tyrosine hydroxylase neurons produce?

Answer 4

the neurotransmitter norepinephrine (NE) which is a catecholamine

Question 5

What receptor does norepinephrine activate?

Answer 5

beta-adrenoceptors on beige/brown adipocyte which in turn promotes UCP-1 expression

Question 6

What does enhanced UCP-1 expression result in?

Answer 6

uncouples oxidation phosphorylation at the expense of ATP to generate heat (body expends energy)

Question 7

What are most adipocytes innervated by?

Answer 7

the sympathetic nervous system

Question 8

You have just conducted an experiment where you have intracerebroventricularly administered AgRP and have found that this has attenuated WAT browning. You are going to conduct an experiment using excitatory DREADDS to activate POMC neurons. Based on your previous findings what is your hypothesis going to be?

Answer 8

the activation of POMC neurons will increase WAT browning

Question 9

What does inhibition of AgRP neurons result in?

Answer 9

decreased food intake and increased energy expenditure

Question 10

You are now going to conduct an experiment using inhibitory DREADD to inhibit AgRP neurons. You have also denervated the left pad fad. What do you hypothesize will happen to WAT browning?

Answer 10

AgRP inhibition will induce WAT browning in the right but not the left

Question 11

How does feeding increase energy expenditure?

Answer 11

via feeding induced thermogenesis (the more calories you eat the more energy you expend)

Question 12

How is energy expenditure measured?

Answer 12

using indirect calorimetry

Question 13

What must occur in order for body weight to remain stable?

Answer 13

changes in food intake must be matched by commensurate changes in energy expenditure

Question 14

What do beige adipocytes utilise a lot of?

Answer 14

glucose to expend energy

Question 15

Which metabolic hormone do you think is signalling to the ARC to coordinate feeding induced thermogenesis?

Answer 15

insulin

Question 16

How are glucose levels maintained in the blood?

Answer 16

kept under strict homeostasis regulation to remain within a set limit

Question 17

Which organ controls the homeostasis of blood glucose levels?

Answer 17

the liver which is innervated by the vagus nerve

Question 18

What does insulin signalling in ARC neurons result in?

Answer 18

coordination of glucose metabolism with feeding

Question 19

What promotes hepatic glucose production?

Answer 19

AgRP activation and POMC inhibition using DREADDS

Question 20

What suppresses hepatic glucose production?

Answer 20

AgRP inhibition or POMC activation using DREADDS

Question 21

What does deletion of the insulin receptor in AgRP or enhanced insulin receptor signalling in POMC neurons result in?

Answer 21

suppression of hepatic glucose production