For more than a century, rodents have played a pivotal role in biomedical research, and provided experimental systems for investigating mammalian biology. Although rats were once the most widely used organism in medical research, mouse research has come to the forefront of scientific and media attention due to the power of mouse genetics and the availability of mouse embryonic stem cells (ESCs). However, with a fully sequenced rat genome and new genome engineering technologies such as TALENs and CRISPR/Cas9, rats are now nearly as genetically tractable as their smaller cousins.
Advantages of rats
Rats are vastly superior to mice as a model system in many avenues of research. Studies in toxicology, hypertension, nutrition, pharmacology, behavior, cancer, osteoporosis, and many other fields strongly benefit from the larger size, superior cognition, and more human-like physiology of rats. Here are some specific examples:
The ovariectomized rat is the most commonly used model for studies of menopause and estrogen deficiency-induced osteoporosis1. These rats display important clinical features of these conditions, and are universally used for testing potential treatments2.
Humanized rats carrying the mutant human gene for SOD1 are very good models of ALS. Due to their larger size, rats can be used to test surgical and injection treatments that are not possible with mice3.
Rats with diabetes induced by streptozotocin, recapitulate much of the biology of human diabetes, and are the most commonly used animal model of diabetes4.
The large size of the rat brain allows precise stereotactic manipulation for studies of brain tumors and CNS function5, and because of their better-performing brains, rats are more reliable and "human-like" in behavioral studies6.
Rewriting the rat genome
Making a rodent model using traditional ESC approaches usually takes more than a year, is very expensive, and is effectively restricted to mice. However, recent advances in nuclease-mediated genome editing via TALEN and CRISPR/Cas9 technologies now allow rapid and inexpensive knockouts and specific point mutations to be made in mice or rats without the need for ES cells. A knockout rat can be made in as little as 2 months for a fraction of the cost of ESC methods. Pronuclear injection to make transgenic rats is also highly efficient. Truly customized rat genetic models are now a reality.
How could your studies benefit from utilizing rat models?
Maybe a rat model should be part of your next project. Could using rats could bolster your results? Cyagen can handle the construction of your rat model from start to finish. Contact us about your ideas for a rodent model system. We will gladly work with you to make the animal that is right for you.
- An YH and Freidman RJ. (1998). Animal Models in Orthopaedic Research. Boca Raton: CRC Press.
- Kharode YP, Sharp MC, Bodine PV. (2008). Utility of the ovariectomized rat as a model for human osteoporosis in drug discovery. Methods Mol Biol. 455:111-24
- Aoki M, Kato S, Nagai M, Itoyama Y. (2005). Development of a rat model of amyotrophic lateral sclerosis expressing a human SOD1 transgene. Neuropathology. 25:365-70
- Rees DA and Alcolado JC. (2005). Animal models of diabetes mellitus. Diabet Med. 22:359-70
- Van Meir EG. (2009). CNS Cancer: Models, Markers, Prognostic Factors, Targets, and Therapeutic Approaches. New York: Humana Press.
- Iannaccone PM and Jacob HJ. (2009). Rats! Dis Model Mech. 2:206-210