Endocrine Weight Loss Endocrine System 5 — Questions and Answers
Question 1: Which enzyme in adipose tissue converts inactive cortisone to active cortisol locally, amplifying fat storage signals?
- Aromatase (CYP19A1)
- 11-beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) (Correct answer)
- Lipoprotein lipase (LPL)
- Hormone-sensitive lipase (HSL)
Correct answer: 11-beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1)
11β-HSD1 is overexpressed in visceral fat of obese individuals, regenerating active cortisol from cortisone and promoting abdominal fat accumulation.
Question 2: Ozempic (semaglutide) achieves weight loss by acting as an agonist at which receptor?
- Leptin receptor (LepR)
- Glucagon-like peptide-1 receptor (GLP-1R) (Correct answer)
- Melanocortin-4 receptor (MC4R)
- Neuropeptide Y receptor (NPY1R)
Correct answer: Glucagon-like peptide-1 receptor (GLP-1R)
Semaglutide mimics endogenous GLP-1, activating GLP-1 receptors in the brain and gut to reduce appetite, slow gastric emptying, and lower blood glucose.
Question 3: A patient has elevated fasting glucose, high triglycerides, low HDL, central obesity, and hypertension. This cluster of findings is called:
- Multiple endocrine neoplasia (MEN)
- Metabolic syndrome (Correct answer)
- Cushing's syndrome
- Familial hypercholesterolemia
Correct answer: Metabolic syndrome
Metabolic syndrome is diagnosed when three or more of five criteria are met: large waist, high triglycerides, low HDL, elevated blood pressure, and elevated fasting glucose.
Question 4: Which neuropeptide produced in the hypothalamic arcuate nucleus powerfully stimulates hunger and is suppressed by leptin?
- Alpha-MSH
- Neuropeptide Y (NPY) (Correct answer)
- CART (cocaine- and amphetamine-regulated transcript)
- Oxytocin
Correct answer: Neuropeptide Y (NPY)
NPY is one of the most potent orexigenic signals in the brain; leptin normally suppresses NPY neurons, and leptin resistance allows unchecked NPY activity.
Question 5: Testosterone deficiency in men (male hypogonadism) contributes to obesity mainly through:
- Increased GLP-1 resistance in the gut
- Reduced lipolysis and increased visceral fat accumulation (Correct answer)
- Elevated TSH driving metabolic rate down
- Direct suppression of insulin secretion
Correct answer: Reduced lipolysis and increased visceral fat accumulation
Testosterone promotes lipolysis and muscle mass; deficiency reduces fat burning, increases visceral fat, and worsens insulin resistance.
Question 6: Which hormone, produced by the duodenum, signals the gallbladder to contract and also reduces appetite by acting on the brain?
- Secretin
- Motilin
- Cholecystokinin (CCK) (Correct answer)
- Gastric inhibitory peptide (GIP)
Correct answer: Cholecystokinin (CCK)
CCK is released after fat and protein intake; it triggers gallbladder contraction, slows gastric emptying, and acts on vagal afferents and the brain to promote satiety.
Question 7: Leptin resistance, commonly seen in obesity, means that despite high leptin levels the brain fails to suppress appetite. This is most analogous to:
- Type 1 diabetes, where insulin is absent
- Type 2 diabetes, where insulin is present but cells don't respond (Correct answer)
- Hyperthyroidism, where thyroid hormone is overproduced
- Addison's disease, where cortisol is deficient
Correct answer: Type 2 diabetes, where insulin is present but cells don't respond
Just as type 2 diabetes involves insulin resistance rather than deficiency, leptin resistance involves impaired signaling despite abundant leptin.
Endocrine Weight Loss Endocrine System 5
Which enzyme in adipose tissue converts inactive cortisone to active cortisol locally, amplifying fat storage signals?