BIOM30001 Lecture Notes - Lecture 31: Leptin Receptor, Peptide Yy, Pancreatic Polypeptide
Document Summary
Msh constantly released act as agonist at mc4r. More leptin --> want to prevent eating --> increase pomc-->increase a-msh--> inhibits food intake. Mutation in pomc or mc4r genes results in obesity. Endogenous antagonist to a-msh: binding causes relief of tonic inhibition - increases food intake via the mc4r. Starving --> want more food --> more agrp. More fat --> more leptin --> inhibit release of agrp. Another member is peptide yy released by git. Inhibits food intake late in digestion in contrast to npy. Hypothalamic action: synthetised in arc, released in pvn/lha. Y1, y2 and y5 receptors implicated: y1 and y5 are postsynaptic (stimulate food intake). Y2 is presynaptic, involved in autoinhibition of npy release. Indicates to brain whether need to increase or decrease food intake. Ghrelin increases npy and agrp synthesis & release to initiate a meal. Susceptibility genes more common: in the right environment, will cause obesity.
