Appetite regulation- role of the hypothalamus Flashcards
What is the thrifty gene hypothesis?
Mankind has evolved during thousands of years of starvation. Only obese would survive and therefore genes for obesity have been selected. This gene is now harmful as we are living too long instead of dying at 51
What did the Framingham study reveal?
Average body weight increases by less than 1lb per year from age 25-55
How much does the average human eat per year?
900,000kcal
Why do slight differences in human consumption not result in increases in weight?
There is programming of weight:
Animals that are overfed tend back to their predicted weight when given a free diet
Animals that are food restricted tend to catch up once allowed free food
What will happen if there is no regulation of body weight and energy expenditure per cell is stable?
Weight will increase
What is the effect of hypothalamus on weight?
It is likely that we have a set hypothalamic weight
What does the hypothalamus do?
It is the site of integration of metabolism
Receives inputs both neuronal and hormonal
Controls pituitary hormone secretion, body temperature, sexual behaviour (FSH), plasma osmolality (controls ADH) and autonomic nervous system
What do lesions of the VMH lead to?
Uncontrolled hyperphagia and obesity in rats- satiety centre
What do lesions of the lateral hypothalamus lead to?
Hypophagia and weight loss- feeding centre
What is Neuropeptide Y?
36 AA peptide rich in tyrosine (Y) which stimulates feeding when injected intracerebroventricularly to rats
What is glucagon-like peptide-1?
Satiety factor and animals stop eating and fall asleep after ICV injected
What is leptin?
Large protein (167AAs) discovered due to a point mutation in the obese (ob/ob) mouse and is synthesised in human adipocytes
Where is leptin synthesised?
IN fat
What happens if leptin is given ICV?
Animals eat less
What substances influence feeding?
Leptin, GLP-1, NPY, MCH and Orexin
