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Galanin modulates vagally induced contractions in the mouse oesophagus
Author(s) -
Boudaka A.,
Wörl J.,
Shiina T.,
Shimizu Y.,
Takewaki T.,
Neuhuber W. L.
Publication year - 2009
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/j.1365-2982.2008.01224.x
Subject(s) - galanin , endocrinology , medicine , galanin receptor , chemistry , capsaicin , antagonist , receptor , vagus nerve , receptor antagonist , neuropeptide , biology , stimulation
Nitrergic myenteric neurons co‐innervating motor endplates were previously shown to inhibit vagally induced contractions of striated muscle in the rodent oesophagus. Immunohistochemical demonstration of putative co‐transmitters, e.g. galanin, in enteric neurons prompted us to study a possible role of galanin in modulating vagally mediated contractions in an in vitro vagus nerve‐oesophagus preparation of the mouse. Galanin (1–16) (1–100 nmol L −1 ), in the presence of the peptidase inhibitor, phenanthroline monohydrate, inhibited vagally induced contractions in a concentration‐dependent manner (control: 100%; galanin 1 nmol L −1 : 95.6 ± 1.6%; galanin 10 nmol L −1 : 57.3 ± 6.5%; galanin 100 nmol L −1 : 31.2 ± 8.1%, n = 5). The non‐selective galanin receptor antagonist, galantide (100 nmol L −1 ), blocked the inhibitory effect of galanin (10 nmol L −1 ) while the selective non‐galanin receptor 1 and galanin receptor 3 antagonists, M871 (1 μmol L −1 ) and SNAP37889 (100 nmol L −1 ), respectively, and the nitric oxide synthase inhibitor, N G‐nitro‐ l ‐arginine methyl ester ( l ‐ NAME) (200 μmol L −1 ), failed to affect this galanin‐induced response. Simultaneous application of galantide (100 nmol L −1 ) and l ‐NAME (200 μmol L −1 ) significantly reduced the inhibitory effect of capsaicin (30 μmol L −1 ) on vagally induced contractions when compared with its effect in the presence of l ‐NAME alone or in combination with the selective galanin receptor 2 or 3 antagonists. An inhibitory effect of piperine on vagally induced contractions was reduced neither by galantide nor by l ‐NAME. Immunohistochemistry revealed galanin immunoreactive myenteric neurons and nerve fibres intermingling with cholinergic vagal terminals at motor endplates. These data suggest that galanin from co‐innervating enteric neurons co‐operates with nitric oxide in modulating vagally induced contractions in the mouse oesophagus.