Question

Which of the following strongly suggests that the actions of ghrelin on food intake involve NPY?

1) Ghrelin released from the stomach strongly inhibits NPY release in the hypothalamus.
2) Ghrelin cells in the stomach contain NPY receptors.
3) NPY levels are constant across the day-night cycle.
4) Ghrelin receptors are located on NPY neurons.
5) NPY strongly inhibits the capacity of ghrelin to suppress drinking.

Answer 1

Option 4, which states that ghrelin receptors are located on NPY neurons, strongly suggests that ghrelin's action on food intake involves NPY, as it indicates a direct influence on hunger-signaling pathways in the hypothalamus.

Step-by-step explanation:

The student's question regarding the relationship between ghrelin and food intake as it relates to NPY (Neuropeptide Y) suggests an interest in understanding the hormonal and neural mechanisms regulating hunger and satiety. Out of the given options, number 4) Ghrelin receptors are located on NPY neurons, suggests that the actions of ghrelin on food intake involve NPY.

When the stomach is empty, ghrelin is released, which then acts on the hypothalamus. Ghrelin has a stimulatory effect on NPY neurons in the hypothalamus, which in turn promotes hunger. Therefore, the presence of ghrelin receptors on NPY neurons indicates a direct pathway by which ghrelin can influence feeding behavior through NPY.

Low blood sugar levels stimulate a neurotransmitter that signals the brain to reduce hunger once the stomach is full. Similarly, the integration of hunger and satiety signals occurs in the hypothalamus. Options such as ghrelin inhibiting NPY release, ghrelin cells containing NPY receptors, or NPY inhibiting ghrelin's capacity to suppress drinking are not directly supportive of a stimulatory link between ghrelin and NPY regarding food intake.