Localization of BDNF expression in the developing brain of zebrafish

Abstract

The brain-derived neurotrophic factor (BDNF) gene is expressed in differentiating and post-mitotic neurons of the zebrafish embryo, where it has been implicated in Huntington's disease. Little is known, however, about the full complement of neuronal cell types that express BDNF in this important vertebrate model. Here, we further explored the transcriptional profiles during the first week of development using real-time quantitative polymerase chain reaction (RT-qPCR) and whole-mount in situ hybridization (WISH). RT-qPCR results revealed a high level of maternal contribution followed by a steady increase of zygotic transcription, consistent with the notion of a prominent role of BDNF in neuronal maturation and maintenance. Based on WISH, we demonstrate for the first time that BDNF expression in the developing brain of zebrafish is structure specific. Anatomical criteria and co-staining with genetic markers (shh, pax2a, emx1, krox20, lhx2b and lhx9) visualized major topological domains of BDNF-positive cells in the pallium, hypothalamus, posterior tuberculum and optic tectum. Moreover, the relative timing of BDNF transcription in the eye and tectum may illustrate a mechanism for coordinated development of the retinotectal system. Taken together, our results are compatible with a local delivery and early role of BDNF in the developing brain of zebrafish, adding basic knowledge to the study of neurotrophin functions in neural development and disease.

Neuroanatomical distribution and functions of brain‐derived neurotrophic factor in zebrafish (Danio rerio) brain

“…BDNF mRNAs can be found during early developmental stages (24 to 196‐hpf) in different developing brain regions as is evident from whole‐mount in‐situ hybridization (WISH) studies (De Felice et al, ). In 24 hpf zebrafish embryo, for example, the bdnf gene expression has been observed in the brain regions and sensory epithelia across the entire head of the embryo (De Felice et al, ).…”

“…As a bonus, zebrafish produces a large number of externally fertilized nearly transparent eggs which exhibit highly synchronous and rapid development. Aside from this, the expression of neurotrophins and their tyrosine kinase receptor genes have been well‐documented in the developing zebrafish (De Felice et al, ; Nittoli et al, ).…”

The developmental neurotoxicity of polybrominated diphenyl ethers: Effect of DE‐71 on dopamine in zebrafish larvae

“…With regard to bdnf, it plays a fundamental role in the growth, maturation, differentiation and maintenance of neuronal populations in the central nervous system [37]. In zebrafish embryos/larvae, bdnf is critical in neuronal development, with bdnf knockdown causing severe brain atrophy, with experimental zebrafish larvae lacking most of the neurites [38].…”

Monosodium Glutamate Exposure at Early Developmental Stage Increases Apoptosis and Stereotypic Behavior Risks on Zebrafish (Danio Rerio) Larvae

“…Ratio of Bax/Bcl-2 more than 1 will turn the balance of pro/antiapoptosis towards apoptosis, activating caspase signaling (Chan et al, 2007). Bcl-2 is regulated by brain-derived neurothropic factor (BDNF) (Sheikh et al, 2010) which expressed in 24h-7dpf zebrafish embryo, including in the brain (Felice, et al, 2014). The levels of Bax, Bcl-2, ratio of Bax/Bcl-2 and caspase-3 of 6dpf larvae were higher in 72h MSG treatment than in 24 and 48h counterparts.…”