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

Summary

Here, we describe micropipette-guided drug administration (MDA) as an alternative method to oral gavage that incentivizes the research animal to ingest treatments readily with minimal stress and discomfort.

Abstract

Oral gavage (OG) with the use of a cannula attached to a syringe is one of the most common methods used to deliver precise dosing of compounds to the stomach of research animals. Unfortunately, this method comes with difficulties for both the operator and the research animal. Studies have shown that OG may lead to complications, including esophagitis, perforation of the esophagus, and inadvertent tracheal drug administration. In addition, OG is associated with increased plasma and fecal corticosterone levels (due to stress), altered blood pressure, and increased heart rate, which could negatively influence or bias study results. A previously developed alternative method termed micropipette-guided drug administration (MDA) incentivizes the animal to consume treatments readily in a minimally invasive manner. Herein, we present examples of the use of the MDA technique with treatments reconstituted in different vehicles and demonstrate effective delivery of the varied treatments to multiple different mouse strains. We further demonstrate that MDA is a technique that decreases the timing and invasiveness of drug administration and does not affect the gut microbiome composition as assessed by quantitative analysis of core gut microbial species. Overall, MDA may offer a less stressful and effective alternative to OG.

Introduction

Drug administration to rodent models is commonly achieved via oral gavage (OG), which consists of administering a liquid preparation directly to the stomach using a cannula attached to a syringe containing the solution. This technique results in a consistent and precise dosage of the treatment to the animal, but also carries multiple disadvantages. OG has been scrutinized for not adequately modeling human dietary exposures^1,2. Furthermore, OG increases the risk of unintentional injuries to the upper digestive system (perforation of the esophagus and stomach), aspiration of the administered treatment, and respi....

Protocol

All animal studies were performed following institutional guidelines and under Johns Hopkins University Institutional Animal Care and Use Committee (IACUC) approved protocols M021M197 and M023M195. Mouse strains used (male mice, 7 weeks old) are described in the Table of Materials. The use of male mice was due to their use in the ongoing studies of prostate cancer. The MDA method has previously been shown to be effective in female mice as well^7,17

Discussion

OG can be a significant source of stress in research animals that may create a confounding variable as previously assessed in multiple studies^{7,9,11,12,13,14,15,23}. Due to the invasiveness of OG, alternate techniques have been employed to minimize the chall.......

Materials

Name	Company	Catalog Number	Comments
200 µL pipette tips	Mettler Toledo	17005860
AB SCIEX Triple QTRAP 5500 mass-spectrometric detector	Sciex	N/A
Akkermansia muciniphila strain muc genomic DNA	American Type Culture Collection	BAA-835D-5
Ammonium acetate	Sigma–Aldrich	5.43834
C57BL/6J mice	Jackson Laboratories	Strain# 000664
C. scindens strain 35704	American Type Culture Collection	35704
Cefoxitin	Sagent	NDC25021-109-10
Corn oil	MedChemExpress	HY-Y1888
DMSO	Sigma-Aldrich	D2650
ethanol	Fisher Scientific	AC611050040
Formic acid	Sigma–Aldrich	5.33002
FVB/NJ mice	Jackson Laboratories	Strain# 001800
Glycerol	Sigma–Aldrich	G5516
Hexane	Fisher Scientific	02-002-996
LC-MS grade water	Fisher Scientific	14-650-357
Methanol	Fisher Scientific	02-003-340
Microtainer serum separator tube	Becton Dickinson	02-675-185
Molecular biology grade water	Corning	46-000-CI
NSG mice	Jackson Laboratories	Strain# 005557
PBS	Corning	21-031-CV
Qubit DNA HS kit	Invitrogen	Q32851
Racemic equol-d4	Santa Cruz Biotechnology	sc-219827
Reinforced Clostridial agar	Anaerobe Systems	AS-6061
Reinforced Clostridial broth	Anaerobe Systems	AS-606
S-equol	MedChemExpress	HY-100583
S-equol reference standard for LC-MS	Cayman Chemical	10010173
Single channel pipette	Rainin	17008652
Streptococcus salivarius genomic DNA	American Type Culture Collection	BAA-1024D-5
Sweetened condensed milk	California Farms	B09TGQ7WV8
VSL#3	VSL#3	B07WX1LVHL
β-glucuronidase from Helix pomatia	Sigma–Aldrich	G7017