Control Of Appetite, Metabolic Syndrome, Developmental Origins Of Health And Disease

Question 0

Where is the appetite controlled?

Answer 0

Arcuate nucleus in the hypothalamus.

Question 1

How is appetite stimulated?

Answer 1

Ghrelin is released from the walls of the empty stomach.
Stimulates excitatory primary neurons to release neuro peptide Y and Agouti related peptide
Stimulates appetite

Question 2

What is the role of primary neurones in the arcuate nucleus?

Answer 2

Sense metabolite levels and respond to hormones.

Question 3

What is the role of secondary neurones in the arcuate nucleus?

Answer 3

Synthesise input from primary neurones and coordinate a response via the vagus nerve.

Question 4

How is appetite inhibited?

Answer 4

Release of ghrelin is inhibited by the stretching of the stomach wall
Peptide YY PYY is released by the small intestine
Leptin is released by adipocytes
Insulin and amylin is released from pancreas
Excitatory primary neurones are suppressed by PYY, Insulin and leptin
Inhibitory primary neurones are stimulated by insulin and leptin.
The primary neurones also detect levels of fatty acids and glucose in the blood
The inhibitory neurones release POMC which is cleaved to ACTH, alpha MSH which stimulates melanocortin 4 receptors to suppress appetite, and beta endorphin which produces feelings of euphoria.

Question 5

What does leptin do?

Answer 5

Stimulates inhibitory neurones and inhibits excitatory neurones in the arcuate nucleus of hypothalamus in order to suppress appetite
Induces the expression of uncoupling proteins in mitochondria - produce heat rather than ATP.

Question 6

What is the role of amylin?

Answer 6

Similar to leptin suppresses appetite, decreases glucagon secretion, slows gastric emptying

Question 7

What are the criteria for metabolic syndrome?

Answer 7

Central obesity (waist:hip ratio >0.9 in men, >0.85 in women and/or BMI>30)
Blood pressure over 140/90
Triglycerides over 1.7 mmol/l
HDL7.8mmol/l
Insulin resistance- lowest quartile

Question 8

What is the barker hypothesis?

Answer 8

Correlation between incidence of adult disease (coronary heart disease, hypertension, type 2 DM) and birth weight/placenta weight
Biochemical adaptation occurs in the fetus in response to the supply of nutrients - epigenetic changes (methylation, changes in histone structure) can be passed on to future generations.