In the fasting state, which statement best describes changes in neurotransmitter circuits?

In the fasting state, which statement best describes changes in neurotransmitter circuits?

• A. The ghrelin level increases activity of the POMC neuronal circuit
• B. The insulin level decreases the activity of the AgRP neuronal circuit
• C. The Leptin level change decreases the activity of the AgRP neuronal circuit
• D. The change in the POMC neuronal circuit activity decreases stimulation of the Melanocortin receptors

Answer: (D)

In the fasting state, the body shifts toward promoting food intake by tipping the balance of hypothalamic circuits away from restraint and toward hunger. Ghrelin rises and signals through pathways that activate AgRP/NPY neurons (orexigenic) while insulin and leptin fall, removing their inhibitory influence on these same neurons and reducing stimulation of POMC neurons (anorexigenic). POMC neurons release alpha-MSH, which activates melanocortin receptors (MC3R/MC4R) to suppress appetite. When POMC activity decreases during fasting, less alpha-MSH is produced, leading to decreased stimulation of melanocortin receptors. This aligns with the fasting-driven drive to eat. The other statements don’t fit this pattern: ghrelin’s effect is to boost AgRP/NPY activity, not POMC; insulin and leptin levels fall during fasting, which would lessen their inhibitory effect on AgRP and their stimulatory effect on POMC, not cause the described opposite changes.

In the fasting state, the body shifts toward promoting food intake by tipping the balance of hypothalamic circuits away from restraint and toward hunger. Ghrelin rises and signals through pathways that activate AgRP/NPY neurons (orexigenic) while insulin and leptin fall, removing their inhibitory influence on these same neurons and reducing stimulation of POMC neurons (anorexigenic). POMC neurons release alpha-MSH, which activates melanocortin receptors (MC3R/MC4R) to suppress appetite. When POMC activity decreases during fasting, less alpha-MSH is produced, leading to decreased stimulation of melanocortin receptors. This aligns with the fasting-driven drive to eat.

The other statements don’t fit this pattern: ghrelin’s effect is to boost AgRP/NPY activity, not POMC; insulin and leptin levels fall during fasting, which would lessen their inhibitory effect on AgRP and their stimulatory effect on POMC, not cause the described opposite changes.