It is 1:00 A.M. and a hard-working second-year medical student is intent on finishing her pathology reading assignment. Soon she begins to note that her concentration is fading because 7 hours have passed since she had dinner, and she is feeling famished. Having studied the chapter on ischemic heart disease, she decides to be prudent and forgoes her favorite chocolate cookies, and instead devours two apples, gulping them down with a glass of low-fat milk. Of the following substances, which one was most likely to have increased rapidly when she became hungry and decreased promptly after she finished her healthy snack?
Appetite and satiety are controlled by a complex system of short-acting and long-acting signals. The levels of ghrelin produced in the stomach increase rapidly before every meal and decrease promptly after the stomach is filled. Leptin released from adipocytes exerts long-term control by activating catabolic circuits and by inhibiting anabolic circuits. a-MSH is an intermediate in leptin signaling. TRH and CRF are among the efferent mediators of leptin signaling, and they increase energy consumption.
a-MSH
Corticotropin-releasing factor (CRF)
Ghrelin
Leptin
Environment & Nutritional Pathology