Spatial and Temporal Distribution of Dopaminergic Neurons during Development in Zebrafish

Abstract

As one of the model organisms of Parkinson’s disease (PD) research, the zebrafish has its advantages, such as the 87% homology with human genome and transparent embryos which make it possible to observe the development of dopaminergic neurons in real time. However, there is no midbrain dopaminergic system in zebrafish when compared with mammals, and the location and projection of the dopaminergic neurons are seldom reported. In this study, Vmat2:GFP transgenic zebrafish was used to observe the development and distribution of dopaminergic neurons in real time. We found that diencephalons (DC) 2 and DC4 neuronal populations were detected at 24 h post fertilization (hpf). All DC neuronal populations as well as those in locus coeruleus (LC), raphe nuclei (Ra) and telencephalon were detected at 48 hpf. Axons were detected at 72 hpf. At 96 hpf, all the neuronal populations were detected. For the first time we reported axons from the posterior tubercle (PT) of ventral DC projected to subpallium in vivo. However, when compared with results from whole mount tyrosine hydroxylase (TH) immunofluorescence staining in wild type (WT) zebrafish, we found that DC2 and DC4 neuronal populations were mainly dopaminergic, while DC1, DC3, DC5 and DC6 might not. Neurons in pretectum (Pr) and telencephalon were mainly dopaminergic, while neurons in LC and Ra might be noradrenergic. Our study makes some corrections and modifications on the development, localization and distribution of zebrafish dopaminergic neurons, and provides some experimental evidences for the construction of the zebrafish PD model.

Late onset of Syt2a expression at synapses relevant to social behavior

“…The ventral telencephalon has only a few TH expressing neurons, but we expected to see THpositive synaptic puncta in the medAC and in the region adjacent to the medAC (Fig.5D-D''), as suggested by previous studies that traced the projections of dopaminergic neurons (Du et al, 2016). Indeed, we found TH puncta in and adjacent to the medAC, and these puncta colocalized with Syt2a, suggesting that TH is located in presynaptic terminals ( Fig.5D-D'').…”

Organization of the catecholaminergic systems in the brain of lungfishes, the closest living relatives of terrestrial vertebrates

“…Posterior tubercular dopamine neurons in zebrafish project mostly to the hypothalamus and the spinal cord and, thus, may correspond to the caudal diencephalic groups of mammals (McLean & Fetcho, ; Tay et al, ; Forlano et al, ). In turn, dopaminergic projections were demonstrated from the posterior tubercle to the telencephalic subpallium, which led to a comparison with the amniote ventral tegmental area/substantia nigra (Rink & Wullimann, ; Schweitzer & Driever, ; Du et al, ), an idea reinforced mainly by the total absence of dopaminergic cells in the mesencephalon of actinopterygians (Yamamoto & Vernier, ). However, this comparison has been thoroughly challenged on the basis of developmental gene expression patterns and a detailed analysis of single neuron projections (Filippi et al, ; Tay et al, ; Yamamoto & Vernier, ; Schweitzer et al, ).…”

Comprehensive Analysis of Neurotoxin-Induced Ablation of Dopaminergic Neurons in Zebrafish Larvae

“…Given the ambiguity in alternative neurotoxin-mediated studies, the current study aimed at providing direct comparisons on the in vivo effects of PD-inducing neurotoxins to identify the optimal candidate for DAnergic neuron ablation and motor phenotypes. All treatments were conducted starting at 3 dpf to prevent the inhibition of neurogenesis and because there is, at this time, near complete DAnergic differentiation and BBB development [12]. The varying concentrations used were to determine the optimal dose for each compound that would result in greater than 50% survival and could be used in subsequent analyses.…”

“…The zebrafish (Danio rerio) has proven to be a robust 2 of 16 in vivo vertebrate animal model for the studies of various neurodegenerative diseases [9,10] and high-throughput drug screening [11] due to their large clutch size and transparent ex utero embryogenesis. With~87% of their genome similar to humans, zebrafish also display a variety of conserved molecular and pathological pathways [12]. In particular, a proportion of the DAnergic system in zebrafish (primarily in the ventral diencephalic region) is postulated to be functionally homologous to that of the nigrostriatal pathway in mammals [13,14].…”

“…In particular, a proportion of the DAnergic system in zebrafish (primarily in the ventral diencephalic region) is postulated to be functionally homologous to that of the nigrostriatal pathway in mammals [13,14]. Dopaminergic projections in zebrafish are fully formed by 3-4 days post-fertilization (dpf) [12,15] compared to E12.5 observed in mice [16], E20 in rats [17], and by embryonic day 73 in macaques [18]. The rapid neurodevelopment and optical transparency throughout embryogenesis in zebrafish allow for facilitated study of DAnergic-related diseases such as PD.…”