All are true about Leptin EXCEPT:
It increases appetite
It is increased in obesity
Its receptor is in hypothalamus
Expressed in adipose tissue
Leptin is a protein secreted by adipocytes (of the white adipose tissue). It is related to cytokines; hence sometimes it is called adipocytokine. Option D is a correct. It is sends signals to the hypothalamus regarding the degree of adiposity and nutrition, which in turn controls eating behavior and energy expenditure. Option C is a correct. As fat stores increase, plasma leptin levels increase (option B); and, as the fat stores are depleted, leptin levels decrease. High leptin levels inhibit the neuropeptide Y (NPY) secreting neurons of the hypothalamus. NPY is an orexigenic agent; inhibition of NPY neurons will decrease the appetite and food intake.Thus, option A is an incorrect. Diet-induced obesity, advanced age, and type II DM are associated with leptin resistance. Leptin signaling mechanism is ineffective in such conditions.
Endocrine System