Galanin-like peptide is target for regulation by orexin in the rat hypothalamus

Galanin-like peptide (GALP) is a newly discovered 60 amino acid peptide from the porcine hypothalamus. GALP has been shown to be expressed predominantly in the arcuate nucleus (ARC) of the rat hypothalamus. a region considered to be one of the most important feeding-regulating centers in the brain. GALP-containing neurons in the ARC express leptin receptors. but relationships between GALP and other feeding-regulating neurons ha c not yet been fully elucidated. Given that Orexin (OX)-containing neurons make synaptic inputs to the ARC, we thus examined the relationship between GALP and OX in the ARC by use of a dual immunostaining technique. OX-immunoreactive fibers appeared to be closely apposed to GALP-immunoreactive cell bodies and their processes. We also examined. whether the OX receptor. OX1-R was expressed in the GALP-containing neurons. Immunoreactivity for both OX1-R and GALP was detectable in 9.6% neurons (range 4.2-14.6%) in the ARC. These findings strongly, suggest that GALP may participate in the regulation of feeding behavior under the influence of leptin and OX. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.