Proopiomelanocortin (POMC) and its derived peptides, in particular alpha-MSH, have been shown to play a crucial role in the regulation of hunger, satiety and energy homeostasis. Studies in patients with anorexia nervosa (AN) suggest an abnormal expression of appetite-regulating hormones. Hormone expression levels may be modulated by epigenetic mechanisms, which were recently shown to be implicated in the pathophysiology of eating disorders.
To explore the pathophysiological role of leptin in obesity-related hypertension, we examined cardiovascular phenotypes of transgenic skinny mice whose elevated plasma leptin concentrations are comparable to those seen in obese subjects. We also studied genetically obese KKA(y) mice with hyperleptinemia, in which hypothalamic melanocortin system is antagonized by ectopic expression of the agouti protein. Systolic blood pressure (BP) and urinary catecholamine excretion are elevated in transgenic skinny mice relative to nontransgenic littermates.
The melanocortin system coordinates the maintenance of energy balance via the regulation of both food intake and energy expenditure. Leptin, a key adipogenic hormone involved in the regulation of energy balance is thought to act by stimulating production, in the hypothalamic arcuate nucleus, of alpha-melanocyte stimulating hormone (alphaMSH), a potent agonist of MC3/4 melanocortin receptors located in the paraventricular nucleus of the hypothalamus. Additionally leptin inhibits release of agouti-related protein (AgRP), an MC4R antagonist.