Tet-On induction with doxycycline after gene transfer in mice: sweetening of drinking water is not a good idea.

Gene transfer to skeletal muscle leads to long-term, stable expression of transferred genes. An exiting development is the use of inducible expression systems. Using the inducible Tet-On system, it has been customary to administer doxycycline in drinking water with added sucrose to ameliorate the bitter taste. During a study aiming at regulating electrotransferred genes through the Tet-On system, we observed excessive drinking behavior among mice. Removal of sugar from the drinking water led to normal drinking behavior and most importantly did not affect the level of gene expression. Based on this study, the practice of adding sucrose to drinking water in doxycycline induction studies should be abandoned.