Use of Micropipette-Guided Drug Administration as an Alternative Method to Oral Gavage in Rodent Models

We are a prostate cancer research lab, and we are studying the effect of human host microbes and their metabolites on prostate cancer initiation and treatment response. We're currently using mouse models to study specific microbial metabolites that we think may influence prostate cancer treatment response. We needed a method to orally administer research compounds to mice daily.

The most commonly used method, oral gavage, can be stressful to research animals and can cause experimental bias. Therefore, we explore the micropipette-guided drug administration, MDA, as an alternative method. We determined that MDA is a technique that decreases the timing and invasiveness of oral drug administration to research animals.

Overall, we demonstrated that MDA may offer a less stressful and effective alternative to oral gavage. To begin, measure the sweetened condensed milk in a 15-milliliter conical tube. Then, using a 50-milliliter conical tube, mix molecular biology-grade water with the sweetened condensed milk slowly.

Next, gently hold the scruff of the study animal's neck with one hand to restrain it. Using a single-channel pipette and a 200-microliter tip, offer the animal 100 microliters of sweetened milk solution. Reconstitute S-equol in DMSO combined with 90%corn oil.

Mix 220 microliters of aliquot S-equol in corn oil with 480 microliters of the sweetened condensed milk-water solution. Similarly, prepare the vehicle without adding S-equol. Make a master mix of the PBS control, DMSO vehicle, and S-equol solutions to deliver a homogeneous solution to all the animals.

Finally, administer 100 microliters of the respective solution to each mouse once daily. Blood analysis revealed that the equol-treated mice had detectable circulating levels of equol, demonstrating effective drug delivery.