title: Disruption of Epithalamic Left-Right Asymmetry Increases Anxiety in Zebrafish.
abstract: Differences between the left and right sides of the brain are found throughout the animal kingdom, but the consequences of altered neural asymmetry are not well understood. In the zebrafish epithalamus, the parapineal is located on the left side of the brain where it influences development of the adjacent dorsal habenular (dHb) nucleus, causing the left and right dHb to differ in their organization, gene expression, and connectivity. Left-right (L-R) reversal of parapineal position and dHb asymmetry occurs spontaneously in a small percentage of the population, whereas the dHb develop symmetrically following experimental ablation of the parapineal. The habenular region was previously implicated in modulating fear in both mice and zebrafish, but the relevance of its L-R asymmetry is unclear. We now demonstrate that disrupting directionality of the zebrafish epithalamus causes reduced exploratory behavior and increased cortisol levels, indicative of enhanced anxiety. Accordingly, exposure to buspirone, an anxiolytic agent, significantly suppresses atypical behavior. Axonal projections from the parapineal to the dHb are more variable when it is located on the right side of the brain, revealing that L-R reversals do not necessarily represent a neuroanatomical mirror image. The results highlight the importance of directional asymmetry of the epithalamus in the regulation of stress responses in zebrafish.
authors.affiliation: Carnegie Institution for Science, Department of Embryology, Baltimore, Maryland 21218.
authors.forename: Lucilla
authors.initials: L
authors.lastname: Facchin
authors.affiliation: Carnegie Institution for Science, Department of Embryology, Baltimore, Maryland 21218.
authors.forename: Erik R
authors.initials: ER
authors.lastname: Duboué
authors.affiliation: Carnegie Institution for Science, Department of Embryology, Baltimore, Maryland 21218 halpern@ciwemb.edu.
authors.forename: Marnie E
authors.initials: ME
authors.lastname: Halpern
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D030801:Animals, Genetically Modified; D014151:Anti-Anxiety Agents / Q000494:pharmacology / Q000627:therapeutic use; D001007:Anxiety / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D002065:Buspirone / Q000494:pharmacology / Q000627:therapeutic use; D003463:Cues; D004195:Disease Models, Animal; D019261:Epithalamus / Q000473:pathology*; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D007839:Functional Laterality / Q000502:physiology*; D006854:Hydrocortisone / Q000378:metabolism; D007100:Imitative Behavior / Q000187:drug effects / Q000502:physiology; D007814:Larva; D008124:Locomotion; D010775:Photic Stimulation; D010870:Pineal Gland / Q000502:physiology / Q000601:surgery; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D014151:Anti-Anxiety Agents; D051858:Forkhead Transcription Factors; D029961:Zebrafish Proteins; C491002:foxd3 protein, zebrafish; D002065:Buspirone; D006854:Hydrocortisone
keywords: buspirone; cortisol; habenula; interpeduncular nucleus; stress