Although the level of leptin secretion is proportional to the amount of fat in adipose tissue, obese individuals are resistant to the anorexigenic effects of the increased hormone levels. Which of the following hypothalamic hormones would be expected to have the greatest increase in expression as a consequence of obesity-induced leptin resistance?

Question

Quizplus · Accepted Answer

In obesity-induced leptin resistance, the anorexigenic effects of leptin are diminished, leading to increased expression of orexigenic hormones like neuropeptide Y (NPY), which stimulates appetite.  Peripheral hormones that act on the ARC and thereby affect the actions of NPY (and AgRP) are leptin and ghrelin. Leptin binds to its receptor present on NPY neurons and inhibits their firing resulting in reduced GABA release onto POMC neurons. This leptin-induced reduction in GABA action at POMC neurons is a disinhibition and allows for increased release of the anorexigenic peptide, α-MSH. This is, in part, the mechanism by which leptin decreases feeding behaviors. Loss of leptin effects on NPY and POMC neurons would lead to increased orexigenic responses contributing to obesity.

Although the Level of Leptin Secretion Is Proportional to the Amount