Ong, K. (2008). Mice for Men

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The mouse has been the mainstay of laboratory research on human illness and will most likely remain an important player in future studies. About 25 million mice are used in laboratories around the world to test new drugs and new notions about the biochemical machinery of living organisms.

There are many animals that can be used in animal testing; but why does it need to be mice? Mice are used because it is said that mice and men have a common ancestor.


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International teams of researchers recently published a nearly complete sequence of the genetic instructions of "Black 6", the most common breed of laboratory mouse, and matched its traits with the recently decoded human genome (Russell 2002). Surprisingly, comparison of the sequences shows that mice and humans came from a common ancestor known as Eomaia scansoria, the earliest known representative of the Eutheria lineage that gave rise to placental mammals (Russell 2002). This common origin implies common genes, and this similarity allows mice to be a reliable animal for testing products destined for human use.

III

Mice and humans both have about 30,000 genes, 85% of which are the same. It is also said that 90% of genes associated with disease are identical in humans and mice. The assumption behind animal testing is that because of these genes, mice are a good model for physiological responses in the human that result from exposure to drugs, and even to new kinds of food and food supplements.

One example of the use of mice in developing new products is green tea extract. Green tea extract does make mice stronger swimmers, Japanese researchers report (De Noon 2005). Ten weeks of green tea supplements plus strenuous exercise made mice swim longer and stronger than mice that swam their laps without supplements. "We have shown that green tea extracts are beneficial for improving endurance capacity, and that this effect is accompanied by a stimulation of [fat] metabolism," Takatoshi Murase writes (De Noon 2005). Mice results suggest that green tea extract may be a useful tool for improving endurance in humans.

However, Murase calculates that the amount of green tea eaten by the mice would work out to about 4 cups of green tea a day for a 165-pound human athlete, about a little less than a liter of tea a day (De Noon 2005).

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However, simply having the same, or rather similar, genes is not enough to justify using mice as human substitutes because the genes are not identical and are probably not regulated in the same way; nor do they interact with other genes in the same way in different species. Thus, we need to use other animals that can fill in for the genes of humans that do not behave in the same way in the rats. That is why dogs, monkeys, and other animals are used. Often the choice of animal depends on the physiological response targeted, such as the choice of rabbits for testing eye medications or the choice of monkeys for testing human vaccines. By using several animal substitutes, a more complete drug effect picture is obtained, allowing more accurace predictions about the consequences of making the substances available for human use.

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Mice will continue to be among the best model organismfor human beings. Moreover, using mice in animal testing results in a fast pace of drug research, since mice are also cheaper, easier to find and maintain, and less ethically constrained than are human subjects.

Since mice are already the ones used in testing many new products, there is much less need for humans to risk their health in trying even simple but new products first.

References:
1. De Noon, D.J. 2005. Green tea performance secret. http://www.cbsnews.com/stories/2005/01/28/health/webmd/main670072.shtml. Accessed February 2008.
2. Russell, S. 2002. Of mice and men. San Francisco Chronicle, 5 Dec 2002. Accessed online from http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2002/12/05/MN153329.DTL&type=science.

(Kathleen Ong is a student at the University of Asia and the Pacific. kathong20@yahoo.com)