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Dendritic synthesis and release of the neuropeptide galanin: Morphological evidence from studies on rat locus coeruleus neurons
Author(s) -
VilaPorcile Évelyne,
Xu ZhiQinq David,
Mailly Philippe,
Nagy Frédéric,
Calas André,
Hökfelt Tomas,
Landry Marc
Publication year - 2009
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22105
Subject(s) - galanin , locus coeruleus , neuropeptide , biology , in situ hybridization , immunocytochemistry , medicine , endocrinology , microbiology and biotechnology , neuroscience , central nervous system , messenger rna , biochemistry , gene , receptor
Dendritic synthesis and release of neuropeptides have been demonstrated in hypothalamic neurosecretory neurons. Here we tested whether this mechanism may be applicable to galanin in rat locus coeruleus (LC) neurons. Light and electron microscopic immunocytochemistry demonstrated the occurrence of galanin peptide in secretory granules within dendritic processes. In situ hybridization at the light and electron microscopic level showed galanin mRNA in these LC processes. Moreover, the levels of the transcript and its extension into the dendrites were significantly increased by reserpine treatment. Finally, evidence for exocytotic release from large dense‐core vesicles in LC dendrites was obtained by using tannic acid‐treated slices. Taken together, these results indicate that galanin can be synthesized in, and possibly released from, LC. These data support a key function of the neuropeptide galanin as an auto‐paracrine local modulator in a major, strongly divergent monoaminergic regulatory system. J. Comp. Neurol. 516:199–212, 2009. © 2009 Wiley‐Liss, Inc.