Wednesday, September 4, 2019

Studying Rodents

Much diabetes research is done in rodents, mostly mice. But mice aren't humans, and they don't always react the same way as humans.

For example, mice have been cured of diabetes many times, but these cures don't translate into human cures. So should we abandon mouse research?

No. The mouse research makes suggestions for things that might work in humans, or in human cell cultures, and raising mice is a lot cheaper and faster than raising larger animals, so many more studies can be done.

However, more attention should be paid to how the mice are raised. Some people criticize mouse studies because they are not controlled for light intensity or electromagnetic fields, which can affect biochemical systems. Others criticize the standard mouse diets.

A recent editorial in the journal Nature discussed the problems with mouse diets. It focuses on obesity research, but obesity and type 2 diabetes are linked.

You can make mice obese pretty quickly by feeding them high-fat diets, which they love; their normal diet is relatively low in fat. Think of baiting a trap with cheese.  But the Nature editorial asks if such high-fat diets have relevance to human obesity that usually develops at much lower dietary fat levels than the mouse obesity.

The editorial also asks if the metabolism of mice raised on a very high fat diet is different from that of mice raised on more normal diets. It also points out that the very high (60%) fat diets usually used to make mice obese quickly have a lot less sucrose than a lower-fat diet would, and sugar has metabolic consequences too.

So too, the types of fatty acids in a diet can affect the metabolism, and the fatty acids in the commercial mouse diets may not be similar to those in a typical (if any diet is typical) human diet.

One thing the editorial didn't address is the fact that many of these diets use the cheapest ingredients available and often satisfy the carbohydrate goal by adding sucrose instead of some kind of healthier carbohydrate like whole grains.

This editorial obviously raises questions rather than providing answers, and at the moment it has no practical value for most people.

However, the fact that people are drawing attention to the quality of the mouse diets used in so much research is a good thing. Maybe better mouse diets will result in better research results.