Tamoxifen

Tamoxifen

Tamoxifen injection protocol

Method Summary

This method describes how to induce expression of cre-recombinase in tamoxifen-inducible transgenic Cre-mouse lines.

Materials

Tamoxifen

• 10mg/ml tamoxifen (final concentration)

Tamoxifen from Sigma, catalogue number: T5648.

Sesame or Peanut Oil

use either sesame or peanut oil

• Sesame Oil from Sigma, catalogue number: S3547
• Peanut Oil missing link

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Method

1. Weigh in 100mg of tamoxifen
2. Resuspend the tamoxifen in 1ml of ethanol (100%) and mix; (this step will take some time; if necessary warm to 37ºC for 20-30 minutes)
3. After tamoxifen is dissolved, add 9ml of sesame or peanut oil
4. Mix on shaker
5. Aliquot and store until use at -20ºC

Injection protocol

• Inject intra-peritoneal (IP) using either of the following dosages:
  1. 20mg/kg/day over 6 days,
  2. 30mg/kg/day over 5 days, or
  3. 80mg/kg/day over 2 (to 3) days.

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Caution

Tamoxifen injection and cre expression may be linked to a transient cardiac hypertrophy reaction in mice. Consider using cre-positive wildtype mice as controls.
References:

1. Cre-loxP DNA recombination is possible with only minimal unspecific transcriptional changes and without cardiomyopathy in Tg(alphaMHC-MerCreMer) mice.
2. Dilated cardiomyopathy resulting from high-level myocardial expression of Cre recombinase.
3. Avoidance of transient cardiomyopathy in cardiomyocyte-targeted tamoxifen-induced MerCreMer gene deletion models.