Hi,

I did similar experiments, studying metabolism using an inducible system in a transgenic mouse line. We therefore ordered food pellets from our supplier (high fat diet or normal chow diet) where doxycyline was supplemented in a concentration of 1g/kg. The food was irradiated but not treated by autoclave.

Cheers

It is indeed said that the bitter taste doxycycline can be "masked" with sucrose (1% weight:volume), but this may have consequences (higher water intake, impact on metabolism). To go around this issue, we have made used of dox-food (from a company called Bioserv), and I have to admit that we have been extremely happy about it.

Check our following paper, we have also compared two doses of dox in food pellets, and we have measured the resulting concentration of dox in the mouse serum:

Centlivre et al., Gene Therapy (2010), 17:14

If you are using the water, you need to add something sweet to mask the taste, or they don't drink enough, though, as others point out, how much sugar you use affects how much water they drink and may also have off target effects. Because of this we also use the Dox food, we get it from Harlan and they can make it to whatever dose you want, I personally have used doses that range from 200mg/kg to 2g/kg, though I know some labs have gone as high as 6g/kg. Though similar caveats may still hold true for the food, I have not measured how much the mice eat, so I can't say for sure, though I have seen a dose response based on a Tre-LacZ reporter, suggesting that, even if they might be eating less at higher doses, they are still getting higher doses.

For reproducible short-term induction, an alternative would be force-feeding DOX solution (see e.g. Mallo et al., Genomics 81 (2003) 356–360). Of course, this procedure must be covered by your animal experimentation license.

I think You should add one more control group for test without sucrose.

Thank you so much, guyes. I have checked that the company providing the dox food is not near our location. so i will still add something into the drinking water,such as Splenda, Aspartame, or Xylitol instead of sucrose. But i do not know which is better for mouse or are they all good taste masking materials?

Yes since Dox is bitter and without sucrose the mice will refuse to drink.

You may try to gavage the mice with Dox water or you may mix Dox in food (company sold).