Endocrine Weight Loss Hormones and Appetite Regulation 2 — Questions and Answers
Question 1: Which neurotransmitter pathway is targeted by phentermine/topiramate ER to suppress appetite?
- Dopaminergic reward pathway
- Sympathomimetic norepinephrine release and GABA enhancement (Correct answer)
- Serotonin 5-HT2C receptor agonism
- Opioid mu-receptor antagonism
Correct answer: Sympathomimetic norepinephrine release and GABA enhancement
Phentermine releases norepinephrine (sympathomimetic effect) to suppress appetite while topiramate enhances GABA activity and inhibits glutamate receptors, together reducing food intake.
Question 2: The melanocortin system's role in weight regulation involves alpha-MSH binding to which receptor to suppress appetite?
- MC1R
- MC2R
- MC3R
- MC4R (Correct answer)
Correct answer: MC4R
Alpha-MSH (a POMC-derived peptide) binds to melanocortin-4 receptor (MC4R) in the hypothalamus to reduce food intake and increase energy expenditure.
Question 3: Cholecystokinin (CCK) contributes to meal termination by:
- Stimulating ghrelin release from the stomach
- Activating vagal afferents that signal satiety to the brainstem (Correct answer)
- Directly suppressing arcuate NPY neurons
- Increasing gastric acid secretion to speed digestion
Correct answer: Activating vagal afferents that signal satiety to the brainstem
CCK released from duodenal I-cells activates vagal nerve afferents that transmit satiety signals to the nucleus tractus solitarius in the brainstem.
Question 4: Sleep deprivation promotes weight gain primarily by affecting which two hormones?
- Increasing leptin and decreasing ghrelin
- Decreasing leptin and increasing ghrelin (Correct answer)
- Increasing insulin and decreasing glucagon
- Decreasing cortisol and increasing adiponectin
Correct answer: Decreasing leptin and increasing ghrelin
Sleep deprivation lowers leptin (reducing satiety signals) and raises ghrelin (increasing hunger), creating a hormonal environment that promotes overeating.
Question 5: Oxytocin's emerging role in appetite regulation involves:
- Stimulating gastric motility and food intake
- Acting as an anorexigenic signal reducing meal size (Correct answer)
- Blocking leptin transport across the blood-brain barrier
- Enhancing dopamine reward for high-fat foods
Correct answer: Acting as an anorexigenic signal reducing meal size
Oxytocin acts on neurons in the hypothalamus and brainstem as an anorexigenic peptide, reducing meal size and food reward; it is being explored as an obesity treatment.
Question 6: Which endocrine change is most directly responsible for increased appetite following significant weight loss?
- Rise in insulin sensitivity
- Sustained elevation of ghrelin with concurrent fall in leptin (Correct answer)
- Increase in adiponectin
- Fall in cortisol
Correct answer: Sustained elevation of ghrelin with concurrent fall in leptin
After significant weight loss, ghrelin rises and leptin falls persistently, creating a hormonal state that drives hunger and opposes weight maintenance.
Endocrine Weight Loss Hormones and Appetite Regulation 2
Which neurotransmitter pathway is targeted by phentermine/topiramate ER to suppress appetite?