Abstract
The development of zinc finger nuclease (ZFN) technology has enabled the genetic engineering of the rat genome. The ability to manipulate the rat genome has great promise to augment the utility of rats for biological and pharmacological studies. A Wistar Hannover rat model lacking the multidrug resistance protein Mdr1a P-glycoprotein (P-gp) was generated using a rat Mdr1a-specific ZFN. Mdr1a was completely absent in tissues, including brain and small intestine, of the knockout rat. Pharmacokinetic studies with the Mdr1a P-gp substrates loperamide, indinavir, and talinolol indicated that Mdr1a was functionally inactive in the blood-brain barrier and intestine in Mdr1a(−/−) rats. To identify possible compensatory mechanisms in Mdr1a(−/−) rats, the expression levels of drug-metabolizing enzyme and transporter-related genes were compared in brain, liver, kidney, and intestine of male and female Mdr1a(−/−) and control rats. In general, alterations in gene expression of these genes in Mdr1a(−/−) rats seemed to be modest, with more changes in female than in male rats. Taken together, our studies demonstrate that the ZFN-generated Mdr1a(−/−) rat will be a valuable tool for central nervous system drug target validation and determining the role of P-gp in drug absorption and disposition.
Footnotes
↵ The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
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ABBREVIATIONS:
- ZFN
- zinc finger nuclease
- NHEJ
- nonhomologous end-joining
- HR
- homologous recombination
- KO
- knockout
- P-gp
- P-glycoprotein
- MDR/Mdr.
- multidrug resistance
- CNS
- central nervous system
- PCR
- polymerase chain reaction
- LC
- liquid chromatography
- MS/MS
- tandem mass spectrometry
- RT
- reverse transcription
- q
- quantitative
- OATP
- organic anion-transporting polypeptide
- AUC
- area under the curve.
- Received June 22, 2011.
- Accepted November 2, 2011.
- Copyright © 2012 The American Society for Pharmacology and Experimental Therapeutics
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