Functional and developmental analysis of the blood-brain barrier in zebrafish.
The blood-brain barrier (BBB) is essential for maintaining brain homeostasis and protecting the brain from toxic substances. Breakdown of this barrier results in severe brain pathologies, whereas impermeability of the BBB is a major obstacle for drug delivery to the brain. Despite its importance, our understanding of the maturation and modulation of the BBB is limited. Zebrafish (Danio rerio) has emerged as a useful model organism for studying vertebrate development and disease mechanisms, as well as for preclinical drug screening. However, the nature of the BBB has not yet been examined in teleost fish. In this paper, we report that with the exception of the circumventricular organs, the cerebral microvessels in zebrafish are impermeable to sulfo-NHS-biotin and horseradish peroxidase (HRP). Brain endothelial cells show immunoreactivity to Claudin-5 and Zonula Occludens-1 (ZO-1), implying the presence of tight junctions in these cells. The expression of Claudin-5 and ZO-1 was detected in cerebral microvessels from 3 days post-fertilization (dpf), concomitant with maturation of the BBB, as determined by restricted permeability to HRP and various fluorescent tracers. Real-time analysis of fluorescent tracer leakage in embryonic zebrafish suggests that they may be used as an in vivo model for BBB breakdown. Taken together, our results show that the endothelial tight junction-based BBB of zebrafish is similar to that of higher vertebrates and thus, zebrafish may be an excellent genetic and experimental model organism for studying development and maintenance of the BBB.
Jeong
Jae-Yeon
JY
Neurovascular Coordination Research Center, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul, Republic of Korea.
Kwon
Hyouk-Bum
HB
Ahn
Jong-Chan
JC
Kang
Dongmin
D
Kwon
Seung-Hae
SH
Park
Jeong Ae
JA
Kim
Kyu-Won
KW
D000818:Animals; D030801:Animals, Genetically Modified; D001692:Biological Transport / Q000502:physiology; D001710:Biotin / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000254:growth & development* / Q000378:metabolism*; D002199:Capillary Permeability; D004625:Embryo, Nonmammalian; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006735:Horseradish Peroxidase / Q000378:metabolism; D008565:Membrane Proteins; D051789:Proto-Oncogene Protein c-fli-1 / Q000096:biosynthesis / Q000235:genetics; D019108:Tight Junctions / Q000502:physiology; D015027:Zebrafish
D008565:Membrane Proteins; D051789:Proto-Oncogene Protein c-fli-1; D049452:Green Fluorescent Proteins; D001710:Biotin; D006735:Horseradish Peroxidase; C021372:horseradish apoperoxidase