GPR39 receptor expression in the mouse brain.

GPR39, an orphan G protein-coupled receptor, has been recently identified as the receptor for the bioactive peptide obestatin. Obestatin is secreted from the stomach and acts as an anti-appetite hormone. This activity is induced whether obestatin is administered intraperitoneally or intracerebroventricularly. GPR39 is known to be expressed in the central nervous system but its precise localization is unknown. In view of the growing importance of this system, we decided to study the sites of GPR39 mRNA expression by in-situ hybridization. We find the highest levels of GPR39 mRNA in the amygdala, the hippocampus, and the auditory cortex and low levels in several other brain regions. Surprisingly, we find no expression of GPR39 in the hypothalamus, expected to be the site of the anorexigenic action of obestatin.