Distribution of galanin-1,-2 and-3 receptor messenger RNAs in central and peripheral rat tissues

Galanin is a neuropeptide widely expressed in the central nervous system an d periphery. In rat, three galanin-binding receptors have been cloned and c haracterized. We report the qualitative and quantitative distribution of ga lanin-l, galanin-2, and galanin-3 messenger RNAs in central and peripheral rat tissues by reverse transcription-polymerase chain reaction and solution hybridization/RNase protection assays, respectively. Galanin-l messenger R NA was detected exclusively in the central and peripheral nervous system wi th highest expression in hypothalamus, amygdala, spinal cord and dorsal roo t ganglia. Galanin-2 messenger RNA was highly expressed in hypothalamus, do rsal root ganglia, and kidney with moderate expression in several other tis sues. Galanin-3 messenger RNA was widely distributed at low to moderate lev els in many central and peripheral tissues. The observed expression of multiple galanin receptors in several tissues in cluding hypothalamus, anterior pituitary and spinal cord supports earlier p harmacological studies suggesting the presence of more than one receptor su btype in these regions. The presence of multiple galanin receptors in these tissues in conjunction with the detection of a single subtype, galanin-2, in tissues such as heart and intestine, illustrates the potential complexit y of galanin-associated actions in rat central nervous system and periphery . (C) 1999 IBRO. Published by Elsevier Science Ltd.