Cognitive, Behavioral, and Systems NeuroscienceResearch PaperEffects of the probiotic Bifidobacterium infantis in the maternal separation model of depression
Section snippets
Animals and housing
Pregnant Sprague–Dawley dams weighing 250–300 g were bred in the animal housing facility, University College Cork. Litters were housed in large breeding cages in a temperature- and humidity-controlled room on a 12-h light, 12-h dark cycle (lights on from 0700–1900 h). At weaning, male rats were group-housed (5–7 rats) in large cages (38×54×26 cm3). Approximately one week prior to drug treatment [postnatal day (P) 40–45], animals were singly housed in smaller polycarbonate cages (25×38×26 cm3)
Body weight
Body weights were significantly reduced in the juvenile MS rats (P35) relative to non-separated controls (effect of MS: 68.27±2.96 g vs. 83.55±3.79 g, t(31)=3.07, P<0.01; see Fig. 1). MS did not affect adult weights at P60 (159.3±12.57 g vs. 177.3±11.49 g, t(16)=0.98, P=0.34; see Fig. 1). At the end of the first week, treatment had a significant effect on body weight gain (effect of treatment: F3,32=3.59, P<0.05). Analysis showed that bifidobacteria-treated MS rats gained less weight relative
Discussion
The present data confirm, and extend, previous findings demonstrating long-term maladaptive alterations to the adult phenotype in rats exposed to repeated MS stress. The impact of MS stress was visible as early as the juvenile period (age 1 month), as evidenced by the reduced body weight in these rats relative to controls. In adulthood (2–4 months), MS induced a decrease in swim behavior and a concomitant increase in immobility in the FST, features considered to reflect a state of behavioral
Conclusion
In summary, this study provides preliminary evidence to suggest that chronic bifidobacteria treatment beneficially affects neuronal systems and behaviors relevant to depression in rats exposed to MS stress in early life, and also identifies some potential mediators of these effects. MS rats treated with the probiotic exhibit a normalization of the peripheral immune response, a reversal of behavioral deficits, and a restoration of basal NA concentrations in the pons area of the brainstem.
Acknowledgments
This study was made possible by a Centre grant (Alimentary Pharmabiotic Centre) from Science Foundation Ireland and a grant from the Higher Education Authority (PRTLI).
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