Galanin is a 29 aa C-terminally amidated (30 aa, non-amidated in humans), highly conserved but unique neuroendocrine peptide originally isolated from intestine. The first 14 aa are fully conserved in almost all species. Galanin is found in the brain and the gut. It modulates a variety of physiological processed including cognition/memory, sensory/pain processing, neurotransmitter/hormone secretion, and feeding behavior. Several N-terminally elongated (-7-29 and -9-29) or truncated biologically active forms of galanin have also been isolated. Galanin antagonists are chimeric peptides generated by linking the amino terminal portion of galanin to substance P (galantide, M15), bradykinin (M35), the neurokinin antagonist spantide (C7) or an idealized alpha helical region (M40). Galanin mediated its biological effects by interacting with high affinity cell surface G-protein coupled receptors (GALR1-3). GALR1 (rat 346 aa; human 349 aa; chromosome 15q24; 55-70kD non-glycosylated and glycosylated forms) are 92% conserved between human and rat. GALR1 is expressed in small intestine, heart prostate, and several areas of the brain (ventral hippocampus, amygdala, supraoptic nucleus, hypothalamus, etc). GALR1 has high affinity for galanin (Kd=0.07 nM), N-terminal galanin fragments, and putative galanin receptor antagonists galantide, C7, M35, and M40. C-terminal galanin fragments do not bind to GALR1.