Open Access Highly Accessed Methodology article

In vivo assessment of the permeability of the blood-brain barrier and blood-retinal barrier to fluorescent indoline derivatives in zebrafish

Kohei Watanabe5, Yuhei Nishimura1234, Tsuyoshi Nomoto5, Noriko Umemoto1, Zi Zhang1, Beibei Zhang1, Junya Kuroyanagi1, Yasuhito Shimada1, Taichi Shintou5, Mie Okano5, Takeshi Miyazaki5, Takeshi Imamura5 and Toshio Tanaka12346*

Author Affiliations

1 Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie, 514-8507, Japan

2 Mie University Medical Zebrafish Research Center, Tsu, Mie, 514-8507, Japan

3 Department of Omics Medicine, Mie University Industrial Technology Innovation Institute, Tsu, Mie, 514-8507, Japan

4 Department of Bioinformatics, Mie University Life Science Research Center, Tsu, Mie, 514-8507, Japan

5 Corporate R&D Headquarters, Canon Inc, Tokyo, Ohta-ku, 146-8501, Japan

6 , 2-174 Edobashi, Tsu, Mie, 514-8507, Japan

For all author emails, please log on.

BMC Neuroscience 2012, 13:101  doi:10.1186/1471-2202-13-101

Published: 16 August 2012



Successful delivery of compounds to the brain and retina is a challenge in the development of therapeutic drugs and imaging agents. This challenge arises because internalization of compounds into the brain and retina is restricted by the blood–brain barrier (BBB) and blood-retinal barrier (BRB), respectively. Simple and reliable in vivo assays are necessary to identify compounds that can easily cross the BBB and BRB.


We developed six fluorescent indoline derivatives (IDs) and examined their ability to cross the BBB and BRB in zebrafish by in vivo fluorescence imaging. These fluorescent IDs were administered to live zebrafish by immersing the zebrafish larvae at 7-8 days post fertilization in medium containing the ID, or by intracardiac injection. We also examined the effect of multidrug resistance proteins (MRPs) on the permeability of the BBB and BRB to the ID using MK571, a selective inhibitor of MRPs.


The permeability of these barriers to fluorescent IDs administered by simple immersion was comparable to when administered by intracardiac injection. Thus, this finding supports the validity of drug administration by simple immersion for the assessment of BBB and BRB permeability to fluorescent IDs. Using this zebrafish model, we demonstrated that the length of the methylene chain in these fluorescent IDs significantly affected their ability to cross the BBB and BRB via MRPs.


We demonstrated that in vivo assessment of the permeability of the BBB and BRB to fluorescent IDs could be simply and reliably performed using zebrafish. The structure of fluorescent IDs can be flexibly modified and, thus, the permeability of the BBB and BRB to a large number of IDs can be assessed using this zebrafish-based assay. The large amount of data acquired might be useful for in silico analysis to elucidate the precise mechanisms underlying the interactions between chemical structure and the efflux transporters at the BBB and BRB. In turn, understanding these mechanisms may lead to the efficient design of compounds targeting the brain and retina.

Blood-brain barrier; Blood-retinal barrier; Zebrafish; Fluorescent indoline derivatives; Transporters