Crash dieter - Gut hormones & obesity

Question 1

GUT HORMONES

i) which cells sense nutrients? what do they release?
ii) which cells release GLP1? which other hormone is co-secreted with GLP1?
iii) which cells secrete gastrin?
iv) what is the only appetite inducing hormone?
v) which area of the small intestine secretes CCK?

Answer 1

i) enteroendocrine cells
- release gut hormones

ii) L cells release GLP1 - co secreted with GIP
iii) G cells secrete gastrin
iv) ghrelin is the only appetite inducing hormone
v) CCK released from proximal SI

Question 2

LEPTIN AND INSULIN

i) which brain area do hormones act on to supress appetite?
ii) which tissue is leptin released from?
iii) which nucleus do leptin and insulin act on?
iv) do leptin and insulin have a positive or negative effect on NYP and melanocortin neurons?
v) what has to happen to PYY for it to have central effects?

Answer 2

i) hypothalamus
ii) leptin is released from fat tissue
iii) act on arcuate nucleus in the hypothalamus
iv) negative effect on NYP and positive effect on melanocortin (supress appetite)
v) needs to be cleaved to 3-36 protein to act centrally

Question 3

ARCUATE NUCLEUS

i) what are the accelerator neurons and do they stimulate or inhibit eating?
ii) what are the brake neurons and do they stim or inhibit eating?
iii) what are insulin and leptin released in proportion to?

Answer 3

i) NPY - stimulate eating
ii) melanocortin - inhibit eating
iii) rel in proportion to fat stores in body

Question 4

SHORT TERM REGULATORS

i) which hormone rises when stomach is empty and fall when food is consumed?
ii) what hormone is released during eating and promotes a sense of fullness?
iii) which neurons are activated to stimulate appetite?

Answer 4

i) Ghrelin
ii) CCK
iii) NPY/AgRP expressing neurons in the arcuate nucleus

Question 5

PYY

i) when does release begin? where is it released from?
ii) which enzyme cleaves it?

Answer 5

i) release begins before nutirents arrives in the intestine and colon
ii) DPP4

Question 6

GLP1

i) which cells produce it?
ii) what is it secreted in response to?
iii) how does it effect insulin secretion?
iv) what hormone is go secreted with it?
v) can it cause hypoglycaemia when used as a drug?

Answer 6

i) enteroendocrine cells - L cells
ii) secreted in relation to food consumption
iii) enhances insulin secretion in a glucose dependent manner
iv) GIP
v) no

Question 7

LEPTIN

i) which cells is it secreted from?
ii) which NT system does it interact with?
iii) does it cause satiety or hunger?

Answer 7

i) adipcoytes
ii) interacts with mesolimbic dopamine system
iii) causes satiety

Question 8

VERY LOW ENERGY DIET

i) how does it affect hunger and desire to eat?
ii) are hormones such as PYY, CCK (promotes satiety), insulin, leptin increased or decreased?
iii) are hormones such a ghrelin, GIP and pancreatic polypep increased or decreased?

Answer 8

i) increased hunger
ii) decreased
iii) increased

Question 9

OBESITY

i) which intervention is the most successful way to lose weight and change hormonal balance?

Answer 9

i) bariatric surgery - sleeve gastrectomy and roux en Y