Research ReportEarly Life Stress Alters Behavior, Immunity, and Microbiota in Rats: Implications for Irritable Bowel Syndrome and Psychiatric Illnesses
Section snippets
Animals
Two cohorts of 2x22 Sprague Dawley rat pups were used in these studies. The pups were housed with their mothers in plastic cages (15 × 22 × 9 cm). The animal room remained temperature-controlled (20 ± 1°C) and on 12-hour light/dark cycle (lights on at 7:00 am).
There were two groups: maternally separated (MS) (n = 11) and non-separated (NS) (n = 11). This study was powered to detect differences at the .05 level. The ethical committee of University College Cork approved the experimental procedure.
Statistical Analysis
All data were normally distributed according to Gaussian distribution analysis. All data are expressed as mean ± SEM. Student t tests were conducted in all in vivo studies except for the cumulative number of visceral pain-related behaviors, where a random coefficient power analysis was used. A two-way analysis of variance (ANOVA) was used to analyze the CRD and the open field data globally. Dendrograms of DGGE banding profiles were constructed to visualize any clustering patterns evident and to
Novel Stress/Open Field
The average number of fecal pellets produced by the MS group was significantly greater (3.1 ± .5 vs. 1.7 ± .3) compared with the NS group [t(22) = 2.45, p < .05].
CRD
In the MS group there was a decrease in the threshold (p < .05) (Figure 1A), compared with control animals. Moreover, there was also an increase in the number of cumulative pain behaviors (p < .05) (Figure 1B). A two-way ANOVA revealed an interaction between pressure and maternal separation [p < .001, F(7,160) = 4.18]. There was also
Discussion
The MS animals displayed diverse phenotypic changes, which is indicative of comorbid anxiety/stress and functional bowel disorders. These occur at a multifunctional level with behavioral alterations suggestive of increased anxiety and visceral hypersensitivity, physiological alterations including elevated HPA-axis function, and increased systemic immune responses; finally, perturbations in gut microbiota were also observed. Together, these data indicate that early life stress induces persistent
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