Effect of the prebiotic lactulose on neurogenesis in a sheep model of early-life stress
Résumé
The olfactory bulb and the hippocampus represent the main regions in the mammalian brain where new neurons continue to be added throughout life. Early-life stress affects the neurogenesis process in these areas. Gut microbiota modulates hippocampal neurogenesis and both probiotics and prebiotics supplementation can prevent the stress-induced reduction in hippocampal neurogenesis. The impact of gut microbiota and its modifications on olfactory neurogenesis has not been explored yet. Here, we investigate the effect of the prebiotic lactulose - an artificial disaccharide- on bulbar neurogenesis in maternally deprived lambs, a sheep model of early-life stress.
Twenty-four female lambs were separated from their mother 24 hours after parturition and randomly assigne the Prebiotic group (P, N=12) or the Control group (C, N=12), housed separately. P lambs were fed with lactulose-suppleented (1%) artificial milk, while C lambs with non-supplemented artificial milk. At eleven weeks of age, olfactory neurogenesis was investigated by quantifying the number of neuroblasts (visualized with doublecortin (DCX) immunistaining) in the granular layer of the main olfactory bulb (MLB). DCX-positive cells were counted manually in frontal sections of the left MOB (four per animal) using Mercator software.
The numer of DCX-positive cells observed in the granular layer of the left MOB did not significantly differ (unpaired t-tes : t(71)=1.54, P=0.128, two -tailed) between P lambs (mean± SEM = 35.18 ± 2.17 cells/mm2} and C lambs (31.31 ± 1.45 cells/mm2).
We found no evidence that lactulose supplementation affects olfactory neurogenesis in maternally deprived lambs. However, we are currently investigating whether lactulose modulates hippocampal neurogenesis.
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