Gastrointestinal motility and morphology in mice: Strain-dependent differences.

Abstract

BALB/c and C57BL/6mice are widely used in biomedical research; however, the differences between strains are still underestimated.Our aims were to develop an experimental protocol to evaluate the duodenal contractility and gastrointestinal transit in miceusing theAlternating Current Biosusceptometry (ACB)techniqueand to compare gastrointestinal motor function and morphology between BALB/c and C57BL/6 strains. Male mice wereused inexperiments (a) duodenal contractility: animalswhich had a magnetic marker surgically fixed in the duodenum to determine the frequency and amplitude of contractions and (b) gastrointestinal transit: animals which ingested a magnetically marked chowto calculate theOro-Anal Transit Time (OATT) and the Fecal Pellet Elimination Rate (FPER). The animals were killedafter the experiments for organ collection andmorphometric analysis. BALB/c and C57BL/6 had two different duodenal frequencies (high and low)with similar amplitudes. After 10hours of monitoring, BALB/c eliminated around 89% of the ingestedmarker and C57BL/6 eliminated33%; OATT and FPER were slower for C57BL/6 compared with BALB/c. The OATT and amplitude of low frequencyhad a strong positive correlation in C57BL/6. For BALB/c, thegastric muscular layer was thickercompared to that measured for C57BL/6. The experimental protocolto evaluate duodenal contractility and fecal magnetic pellets output using the ACB techniquein micewas successfully established.BALB/c strains had higher duodenal frequencies and a shorter timeto eliminate the ingested marker. Our resultsshowed differences in bothmotor function and gastrointestinal morphology betweenBALB/c and C57BL/6 strains.