MAPK1 and Anorexia: Similarly, previous findings have shown a ∼2-fold increase in brain NPY levels in ghrelin-activated neurons under fasting, in underweight anorexia patients, and during food-deprived conditions122–125, which is significantly attenuated by pharmacological inhibition of ghrelin-mediated MAPK1 signaling in neurons48,126, highlighting ghrelin’s specific role in neuron activation and NPY secretion.