Cells releasing orexins (hypocretins) become more active when
A) both leptin and ghrelin levels are high.
B) both leptin and ghrelin levels are low.
C) leptin levels are low and ghrelin levels are high.
D) leptin levels are high and ghrelin levels are low.

Question

Quizplus · Accepted Answer

Orexins (hypocretins) are neuropeptides that regulate wakefulness, appetite, and reward. The release of orexins is stimulated by low levels of leptin (a hormone that signals satiety) and high levels of ghrelin (a hormone that signals hunger), making choice C the best option. High levels of leptin and low levels of ghrelin, as seen in option D, would promote satiety and reduce the release of orexins, while options A and B are contradictory and would not stimulate the release of orexins.

Cells Releasing Orexins (Hypocretins) Become More Active When