A short estrogen-responsive N-terminal galanin homologue found in rat brain and gut with antiserum raised against rat galanin(1-16).
Galanin-like peptide (GALP) is currently the only known galanin(1-29) homologue. However, three different galanin receptors, of which GalR3 exhibits comparatively low affinity for galanin(1-29), and molecular heterogeneity of immunoreactive galanin are arguments for presence of other endogenous galanin homologues. Since antibodies recognize three-dimensional structures of 3-5 amino acids in a peptide, we raised antibodies in rabbits against galanin(1-16) conjugated to bovine serum albumin, looking for the presence of endogenous N-terminal galanin homologues in rat tissues. The antiserum selected had 7,830 times higher avidity for galanin(1-16) compared to galanin(1-29). A single immunoreactive component with a Stokes radius of about 8 amino acids was found. Immunohistochemistry strongly suggested that this immunoreactivity is localised in the same neurons as galanin(1-29). Furthermore, its concentration was increased in response to estrogen treatment in the same brain regions as galanin(1-29), although not as rapidly. The present results indicate the presence of a novel endogenous N-terminal galanin homologue.
Hilke
Susanne
S
Department of Biomedicine and Surgery, Division of Clinical Chemistry, Faculty of Health Sciences, University Hospital, SE-581 82 Linköping, Sweden. sushi@ibk.liu.se
Hökfelt
Tomas
T
Theodorsson
Elvar
E
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004958:Estradiol / Q000097:blood; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D019004:Galanin / Q000378:metabolism*; D007106:Immune Sera; D007150:Immunohistochemistry; D010446:Peptide Fragments / Q000276:immunology*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley
D004967:Estrogens; D007106:Immune Sera; D010446:Peptide Fragments; D004958:Estradiol; D019004:Galanin