Stress and the Commensal Microbiota: Importance in Parturition and Infant Neurodevelopment

Abstract

The body is colonized by an enormous array of microbes that are collectively called the microbiota. During quiescent periods, microbial communities within the gut are relatively resistant to change. However, several factors that disrupt homeostasis can also significantly change gut microbial community structure. One factor that has been shown to change the composition of the gut microbiota is exposure to psychological stressors. Studies demonstrate that the commensal microbiota are involved in stressor-induced immunomodulation, but other biological effects are not yet known. This review discusses emerging evidence that the microbiota can impact the brain and behavior and indicates that stressor-induced alterations in the composition of gut microbial communities contribute to stressor-induced behavioral changes. This review will also discuss the evidence that such effects are most evident early in life, where both stress and the microbiota have been linked to birth outcomes, such as prematurity, and neurodevelopment. When considered together, a paradigm emerges in which stressor-induced alterations in commensal microbial populations significantly impact parturition and infant neurodevelopment.

Prenatal stress disrupts social behavior, cortical neurobiology and commensal microbes in adult male offspring

“…In addition, treating animals with antibiotics to disrupt the microbiome led to changes in social behavior [49]. Stress during gestation alters the composition of the maternal microbiome and these changes are transmitted to the offspring [3,5,6]. Our study shows that offspring microbial changes persist into adulthood with males exposed to PNS demonstrating a significant difference in the gut microbiome.…”

“…The mechanisms underlying this contribution include alterations in epigenetic regulation, the hypothalamic pituitary adrenal (HPA) axis, and inflammation [2]. There is increased focus on changes in the microbiome following PNS as a contributor to increased risk of neuropsychiatric disorders [3,4]. For instance, stress during gestation altered the maternal vaginal microbiome [5] and gut microbiome [6], and the composition of the gut microbiome in adult offspring [6,7].…”

Probiotic supplementation can positively affect anxiety and depressive symptoms: a systematic review of randomized controlled trials

“…diet, probiotic supplementation, disease-related dysbiosis), and genomic influences that directly impact neonatal acquisition and maintenance of bacterial composition across the lifespan (Fig. 2) [59][60][61][62]. Arguably, the neonatal period represents the most developmentally-significant window for the acquisition and establishment of the GI microbiota with important immune and neurodevelopmental implications…”

Prenatal stress-induced alterations in major physiological systems correlate with gut microbiota composition in adulthood

“…Furthermore, in a recent study PNS was shown to affect the composition of the human infant gut microbiota over the first 110 days after birth (Zijlmans et al, 2015). Moreover, there is growing evidence that chronic stress can alter the vaginal microbial ecosystem in the mother, which in turn impairs the initial microbial colonisation of the neonatal intestine (Gur et al, 2015;Jašarević et al, 2015). The maintenance of microbial diversity is important for the normal development of the CNS, as well as gastrointestinal (GI) and respiratory function (Borre et al, 2014;Collins et al, 2014;Desbonnet et al, 2015;Moreno-Indias et al, 2015).…”