Obesity

Question 1

How does leptin stimulate thermogenesis?

Answer 1

binds to receptors in hypothalamus
hypothalamus directs signal via SYMPATHETIC NEURON
Increases expression of UCP-1.
(proton gradient dissipated without synthesising ATP.

Question 2

What are the main actions of incretin hormones?

Answer 2

Enhance insulin secretion 
Reduce glucagon secretion 
Delay gastric emptying 
Decrease appetite (GLP-1Rs on PVN of hypothalamus) 
Increase B-cell mass.

Question 3

What does GIP exclusively act on?

Answer 3

7 TM receptors on B cells.

Question 4

What changes with respect to incretins in type II diabetes?

Answer 4

GIP levels not affected, but reduced insulin stimulatory effects.

GLP-1 secretion is reduced (potential drug candidate!)

Question 5

What is exanatide and exenidine?

Answer 5

Exenidine 4 is a GLP-1 like peptide but not a substrate for DPP-4 (glia monster saliva)!

Exenatide is 39 aa peptide, synthetic form, 50% homology to GLP-1, longer half life & not substrate for DPP-4.

Used since 2007.

Question 6

How are GLP-1 analogues beneficial to T1D?

Answer 6

Reduce glucagon secretion (so circulating glc from gluconeogenesis)

Delay gastric emptying (delayed Glc peak increase)

Weight loss (supplementary insulin leads to weight gain!).

Question 7

What BMI’s constitute; obese, overweight and morbidly obese?

How has the incidence changed?

Answer 7

> 30
25
40
23-34% from 1980 to 2008.

Question 8

What is the effect of PYY?

Answer 8

Reduced food intake

enhanced insulin-stimulated glc uptake.

Question 9

what differs with respect to gastric bands?

Answer 9

no change in gastric emptying (GI tract npt re routed)

inflation of band may stimulate vagal fibres to decrease appetite via signalling to brain regios. regulating food intake.m

Question 10

Describe the production and effects of NPY.

Answer 10

Produced by NPY neurones in the arcuate nucleus.
Binds to Y1R receptors on POMC neurone (prevents anorexigenic)
Binds LHA neurones stimulating orexigenic.