Leptins Flashcards
Leptin is classified as what, and where is it found?
adipokine, released by fat cells in direct proportion to presence of fats. more fat, more leptin
What does leptin do?
Binds to receptors through body and increases sensitivity of muscle cells to insulin, stimulates beta oxidation of fatty acids, and decreases TAG synthesis
Appetite stimulating hormones…?
Neuropeptide Y (NPY) and agouti related peptide (AgRP)
What does leptin do to the appetite stimulating hormones?
It inhibits the neurons that release them (in the arcuate nucleus of the hypothalamus).
Inhibition and Stimulation of NYP and AgRP
leptin inhibits them/fasting stimulates them
Proopiomenalocyte
POMC, in brain: contains leptin receptors
when proteolytically cleaved, yields melanocyte-stimulating hormone (MSH)
MSH ?
melanocyte stimulating hormone, stimulates melanocytes, activates appetite suppressing neurons and inhibits food consumption. fasting inhibits MSH
Regulation of MSH
inhibited by fasting (via AgRP)
RBP4
adipocyte hormone that promotes insulin resistance, “fine tunes” the effects of leptin
resisten
adipocyte hormone that promotes insulin resistance, “fine tunes” the effects of leptin
Why is leptin related to obesity?
Leptin resistance. present in high concentrations in obese people. suppressors of cytokine signaling (SOCS) may take part
GLP-1 and CCK
appetite stimulators
GLP-1
glucagon like peptide 1. secreted by intestinal cells. induces feelings of satiety, inhibits further eating, @ pancreas it inhibits glucagon secretion and stimulates insulin secretion.
released by pancreas acts on brain and intestines
GLP-1’s effects
@ pancrease Increased insulin secretion Increased insulin biosynthesis Increased beta cell proliferation Increased beta cell survival
@ brain
Increased satiety
Decreased good intake
Decreased body weight
CCK’s effects on the brain
Increased satiety
Decreased food intake
Decreased body weight
