Problems in physiological experimental animal models investigated with factorial design

Abstract

In the present study we investigated four variables using factorial design to decide if any of these could explain the variations in the control measurements of interstitial fluid pressure (P if ) in rat trachea that were experienced. This approach requires only a fraction of the animals normally needed when studying each factor separately. P if in tracheal tissue was measured with the servocontrolled counterpressure system using sharpened micropipettes. The measurements were performed over a period of 60 min and are presented as mean for every 15 min period. The factors investigated in the study were: three strains of female rats (Strain) two brands of diets (Food); two breeder companies (Source); and finally two batches of the same set of animals to repeat the experiment twice (Week), using a total of 48 animals. There was a highly significant effect within Strain the first week (p ¼ 0:007), but this response was not observed the second week. The interaction between Strain  Week was significant (p ¼ 0:007) while the main effects Strain or Week alone were not significant. The response pattern for Strain and Food was inconsistent for the two experimental weeks studied. These experiments made it possible for us to simultaneously test several factors and exclude these factors as the reason for the observed changes in our experiments since the experiments did not allow the conclusion that one or several of these factors could explain the variation in P if : r

Edema in Oral Mucosa after LPS or Cytokine Exposure

“…All P if measurements were made by one operator at the exact location, and, therefore, it is more likely that differences are due to variability in animal stocks. Such discrepancies in P if in control animals have been previously reported (Gjerde et al, 2004) and explained by genetic or environmental factors. Despite the variations in in vivo P if , the effects of the investigated agents were clear: No changes in P if were observed in the control groups during the experimental period, whereas lowering of P if occurred with the administration of cytokines and LPS.…”

Planning Experimental Studies and Selection of an Available Animal Model?

“…Standartlaşma bir deneyden elde edilen verilerin ortalamasının, deney tekrarlandığında aynı veya yakın sonuçlar üretilebilmesini amaçlar. Bu da, aynı laboratuarda veya diğer laboratuarlarda yapılan aynı veya benzer çalışmalar-dan elde edilen veriler arasında yakınlığın artmasını ve dolayısıyla araştırma sonuçlarına duyulan güvenin artması-nı sağlar [15].…”

“…Yetiştirilme özelliklerine göre laboratuar hayvanı seçimi [6,15] inbred: Bir ana babadan doğan yavruların çiftleştilerek yapı-lan üretim şeklidir. Bunun amacı genetik heterojeniteyi azaltıp homojeniteyi artırarak genetik değişkenliği azaltmaktır.…”