Appetite And Metabolic Syndrome

Question 1

Neurones of the arcuate nucleus

Answer 1

Two types of primary neurone 
Stimulatory neurones 
- contain NPY and AgRP
- promote hunger 
Inhibitory neurones 
- contain POMC (cleaved to ACTH and alpha-MSH) 
- promote satiety 
Primary neurones synapse with secondary neurones in other regions of the hypothalamus and the signals integrate to alter feeding behaviour

Question 2

Hormonal signals from gut to hypothalamus

Answer 2

Ghrelin (the only hunger hormone)
- peptide hormone release from stomach wall when empty
- stimulates appetite
PYY (peptide tyrosine tyrosine)
- released by cells in ileum and colon in response to feeding
- suppresses appetite

Question 3

Hormonal signals from body to the hypothalamus

Answer 3

Leptin (loss of leptin gene –> constantly hungry –> need leptin injections)
- released into blood by adipocytes
- stimulates the inhibitory POMC neurones
- inhibits the excitatory AgRP/NPY neurones
- suppresses appetite
Insulin
- suppresses appetite
Amylin
- peptide hormone secreted by B cells in pancreas
- suppresses appetite
- pramlintide is an amylin analogue approved for treatment of type 2 diabetes

Question 4

Control of appetite

Answer 4

Appetite control centre (satiety centre) is located in the hypothalamus
The arcuate nucleus (can sense FA and hormones in the bloodstream) - plays a central role in controlling appetite

Question 5

Metabolic syndrome

Answer 5

• a cluster of the risk factors associated with cardiovascular disease
  Combined the symptoms represent a very serious risk
• abdominal obesity ** (contributes to hypertension, high cholesterol and hyperglycaemia)
• high blood pressure
• insulin resistance ** (high plasma glucose so more insulin production, pancreatic beta cells become worn out, hyperglycaemia leads to type 2 diabetes)
• raised fasting glucose
• dyslipidaemia (low HDL high TAGs)
  20-25% of adults, 40% of over 40s
  Primary intervention
• healthy lifestyle with moderate calorie intake and an increase in physical activity
  Secondary intervention
• drug intervention for more high risk
• statins to reduce LDL cholesterol, antihypertensive drugs to lower blood pressure

Question 6

Developmental origins of adult health and disease (DOHaD)

Answer 6

• birth weight is linked with a variety of diseases
• lower weight - metabolism is set to expect harsh conditions - if food in plentiful supply then obesity is common
  epigenetics
• DNA methylation (modifications can be passed on)
• DNA histone modification
• non coding RNAs
  All alter which genes are expressed and which aren’t