Intraperitoneal Injection of Tamoxifen for Inducible Cre-Driver Lines
Protocol compiled by Caleb Heffner, 7/25/2011.
Tamoxifen induction regimens should be determined empirically for the specific mouse lines and experimental setup involved. However, the following protocol provides a starting point for the induction of Cre in adult (P56) mice. The following procedure has been used with success to induce robust Cre activity in all major organ systems (validated in ubiquitous Cre /ER expressers, such as B6.Cg‐Tg(UBC‐cre/ERT2)1Ejb/J, JR#8085).
Materials and Reagents:
- Tamoxifen (Sigma‐Aldrich), CAS # 10540‐29‐1
- Corn Oil
- Ethanol (for disinfection)
- 1 ml Syringe (BD)
- 3/8” beveled needle – 26 gauge (BD)
Tamoxifen is a hazardous substance. Review the MSDS, wear appropriate PPE, and, if possible, house mice in disposable pens in a separate animal room for the duration of injections.
- Dissolve tamoxifen (Sigma‐Aldrich) in corn oil at a concentration of 20 mg/ml by shaking overnight at 37°C. Tamoxifen is light sensitive, and should be made and stored in a light‐ blocking vessel (amber, or foil wrapped). After tamoxifen is in solution, store at 4°C for the duration of injections.
- Determine injection dose by weight, using approximately 75 mg tamoxifen/kg body weight. For adult mice, a standard dose of 100µl tamoxifen/corn oil solution (above) is effective for inducing recombination.
- Administer tamoxifen via intraperitoneal injection (using an ACUC approved injection procedure) once every 24 hours for a total of 5 consecutive days. As a safeguard, sanitize injection site with 70% ethanol prior to injection.
- Following the final injection, mice should be quarantined for 24 hours before returning to their normal animal room. Disposable pens and bedding should be discarded at this time. For Cre characterization work at the Jackson Laboratory, there is a 7‐day waiting period between the final injection and necropsy/histological analysis.
- Throughout the course of tamoxifen injections and any post‐injection wait period, mice should be closely monitored for any adverse reactions to the treatment.
Madisen, L., et. al., Nat Neurosci. 2010; 13(1): 133–140
Sohal, D., et. al., Circ. Res. 2001; 89: 20‐25