title: Cholinergic left-right asymmetry in the habenulo-interpeduncular pathway.
abstract: The habenulo-interpeduncular pathway, a highly conserved cholinergic system, has emerged as a valuable model to study left-right asymmetry in the brain. In larval zebrafish, the bilaterally paired dorsal habenular nuclei (dHb) exhibit prominent left-right differences in their organization, gene expression, and connectivity, but their cholinergic nature was unclear. Through the discovery of a duplicated cholinergic gene locus, we now show that choline acetyltransferase and vesicular acetylcholine transporter homologs are preferentially expressed in the right dHb of larval zebrafish. Genes encoding the nicotinic acetylcholine receptor subunits α2 and β4 are transcribed in the target interpeduncular nucleus (IPN), suggesting that the asymmetrical cholinergic pathway is functional. To confirm this, we activated channelrhodopsin-2 specifically in the larval dHb and performed whole-cell patch-clamp recording of IPN neurons. The response to optogenetic or electrical stimulation of the right dHb consisted of an initial fast glutamatergic excitatory postsynaptic current followed by a slow-rising cholinergic current. In adult zebrafish, the dHb are divided into discrete cholinergic and peptidergic subnuclei that differ in size between the left and right sides of the brain. After exposing adults to nicotine, fos expression was activated in subregions of the IPN enriched for specific nicotinic acetylcholine receptor subunits. Our studies of the newly identified cholinergic gene locus resolve the neurotransmitter identity of the zebrafish habenular nuclei and reveal functional asymmetry in a major cholinergic neuromodulatory pathway of the vertebrate brain.
authors: Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218.
authors: Elim
authors: E
authors: Hong
authors: Kirankumar
authors: K
authors: Santhakumar
authors: Courtney A
authors: CA
authors: Akitake
authors: Sang Jung
authors: SJ
authors: Ahn
authors: Christine
authors: C
authors: Thisse
authors: Bernard
authors: B
authors: Thisse
authors: Claire
authors: C
authors: Wyart
authors: Jean-Marie
authors: JM
authors: Mangin
authors: Marnie E
authors: ME
authors: Halpern
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002795:Choline O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004558:Electric Stimulation; D007839:Functional Laterality / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D019262:Habenula / Q000378:metabolism / Q000502:physiology*; D017403:In Situ Hybridization; D007814:Larva / Q000502:physiology; D023421:Models, Animal; D008969:Molecular Sequence Data; D009434:Neural Pathways / Q000502:physiology; D062308:Optogenetics; D018408:Patch-Clamp Techniques; D011978:Receptors, Nicotinic / Q000378:metabolism; D017423:Sequence Analysis, RNA; D013681:Tegmentum Mesencephali / Q000378:metabolism / Q000502:physiology*; D050494:Vesicular Acetylcholine Transport Proteins / Q000378:metabolism; D015027:Zebrafish
chemical_list: D017931:DNA Primers; D011978:Receptors, Nicotinic; D050494:Vesicular Acetylcholine Transport Proteins; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine
keywords: addiction; electrophysiology; optogeneticis; tachykinin 1