Chemical Identity

Property	Value
Name	Galanin
Gene	GAL (chromosome 11q13)
Sequence	Gly-Trp-Thr-Leu-Asn-Ser-Ala-Gly-Tyr-Leu-Leu-Gly-Pro-His-Ala-Val-Gly-Asn-His-Arg-Gly-Ser-Phe
Length	30 amino acids
C-terminal	Amidated
Conservation	90% identity between human and porcine
PDB Structures	2E9H (NMR)

Receptors

Receptor	Gene	Distribution	Primary Effects
GalR1	GALR1	Cortex, hippocampus, hypothalamus	Anxiolysis, analgesia, appetite
GalR2	GALR2	Hypothalamus, hippocampus, spinal cord	Neuroprotection, feeding
GalR3	GALR3	Brain (low expression)	Mood regulation

Physiological Functions

Appetite Regulation

• Galanin stimulates feeding (potent orexigenic)
• Co-localized with NPY in arcuate nucleus
• GalR2 mediates feeding stimulation
• GalR1 mediates fat intake preference

Pain Modulation

• Analgesic: Galanin in dorsal horn reduces pain transmission
• Neuropathic pain: GalR1 activation reduces hypersensitivity
• Co-localized with substance P and CGRP in DRG neurons

Cognition and Memory

• Galanin modulates cholinergic transmission in hippocampus
• GalR1 antagonists improve memory in animal models
• Alzheimer’s disease: Galanin is upregulated in surviving neurons

Neuroprotection

• GalR2 activation protects neurons from excitotoxicity
• Galanin promotes neurite outgrowth
• Anti-inflammatory effects in CNS

Clinical Significance

Galanin Receptor Agonists/Antagonists

Drug	Target	Indication	Status
M40 (galanin analog)	GalR1/GalR2	Obesity	Research
GalR2 agonist (AR-M1896)	GalR2	Feeding	Preclinical
GalR1 antagonist	GalR2260	Memory	Phase II

Disease Associations

• Alzheimer’s disease: Galanin upregulation in surviving neurons
• Epilepsy: Galanin is anticonvulsant
• Depression: GalR1 polymorphisms associated with depression
• Obesity: Galanin stimulates feeding, GalR2 antagonists reduce body weight

Manufacturing

• SPPS (Fmoc): Standard solid-phase synthesis
• C-terminal amidation: Required for activity
• Purification: RP-HPLC
• Characterization: Mass spectrometry, NMR

References

1. Crawley JN. “Galanin and galanin receptors.” Pharmacology & Therapeutics 82:1-13, 1999. doi:10.1016/S0163-7258(97)00040-0
2. Wrenn CC, Crawley JN. “Galanin and feeding.” Peptides 22:1139-1146, 2001.
3. Counts SE, et al. “Galanin in Alzheimer’s disease.” Neurobiology of Disease 16:1-7, 2004.
4. Kuteeva E, et al. “Galanin and galanin receptors in neuropsychiatric disorders.” Frontiers in Neuroscience 5:1-10, 2011.
5. Wrenn CC, et al. “Galanin transgenic mice.” Neuropeptides 36:127-135, 2002.