High-performance liquid chromatography analysis of hypothalamic ghrelin

Ghrelin, first identified in the stomach, is a ligand of an orphan G-protein coupled receptor. Early studies indicated that the growth hormone secretagogue receptor (GHS-R; ghrelin receptor) is ubiquitously distributed in the brain. In addition, centrally administered ghrelin and ghrelin receptor agonist have effects on central neurons in many regions, including the hypothalamus, caudal brain stem, and spinal cord. These effects are due to ghrelin secreted from the brain, rather than from the stomach; ghrelin does not cross efficiently through the blood-brain barrier. Identification of ghrelin in the hypothalamus demonstrated that, as with stomach ghrelin, hypothalamic ghrelin also has two molecular forms, namely, octanoyl ghrelin and des-acyl ghrelin. Hypothalamic ghrelin plays diverse roles in processes including feeding regulation and thermoregulation. Thus, the analysis of hypothalamic ghrelin will provide new information about the action of ghrelin in the central nervous system. In this chapter, we outline high-performance liquid chromatography and real-time PCR analysis of hypothalamic ghrelin.