title: Maternal cortisol stimulates neurogenesis and affects larval behaviour in zebrafish.
abstract: Excess glucocorticoid transferred from stressed mother to the embryo affects developing vertebrate offspring, but the underlying programming events are unclear. In this study, we tested the hypothesis that increased zygotic glucocorticoid deposition, mimicking a maternal stress scenario, modifies early brain development and larval behaviour in zebrafish (Danio rerio). Cortisol was microinjected into the yolk at one cell-stage, to mimic maternal transfer, and the larvae [96 hours post-fertilization (hpf)] displayed increased activity in light and a reduction in thigmotaxis, a behavioural model for anxiety, suggesting an increased propensity for boldness. This cortisol-mediated behavioural phenotype corresponded with an increase in primary neurogenesis, as measured by incorporation of EdU at 24 hpf, in a region-specific manner in the preoptic region and the pallium, the teleostean homolog of the hippocampus. Also, cortisol increased the expression of the proneural gene neurod4, a marker of neurogenesis, in a region- and development-specific manner in the embryos. Altogether, excess zygotic cortisol, mimicking maternal stress, affects early brain development and behavioural phenotype in larval zebrafish. We propose a key role for cortisol in altering brain development leading to enhanced boldness, which may be beneficial in preparing the offspring to a stressful environment and enhancing fitness.
authors.affiliation: Department of Biological Sciences and University of Calgary 2500 University Drive NW Calgary, Alberta, T2N 1N4, Canada.
authors.forename: Carol
authors.initials: C
authors.lastname: Best
authors.affiliation: Department of Medical Genetics, University of Calgary 2500 University Drive NW Calgary, Alberta, T2N 1N4, Canada.
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Kurrasch
authors.affiliation: Department of Biological Sciences and University of Calgary 2500 University Drive NW Calgary, Alberta, T2N 1N4, Canada.
authors.forename: Mathilakath M
authors.initials: MM
authors.lastname: Vijayan
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000473:pathology; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D006854:Hydrocortisone / Q000494:pharmacology*; D017403:In Situ Hybridization; D007814:Larva / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D055495:Neurogenesis / Q000187:drug effects*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000254:growth & development*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D006854:Hydrocortisone; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C476737:neurod4 protein, zebrafish; C515950:orthopedia protein, zebrafish