Absence of the gut microbiota enhances anxiety-like behavior and neuroendocrine response to acute stress in rats

Modulatory Effects of Gut Microbiota on the Central Nervous System: How Gut Could Play a Role in Neuropsychiatric Health and Diseases

“…98 An anxiety prone behavioral phenotype is also seen in germ-free rats, along with elevated CRF expression in the hypothalamus and reduced glucocorticoid receptor (GR) expression in the hippocampus, (GR in this region regulates the CRF response in a negative feedback loop) and along with a lower dopaminergic turnover rate in specific CNS regions. 99 Exposing rats in the early postnatal period to stress by maternal separation also leads to a change in composition of gut microbiota, which is linked to a long-term increase in anxiety-like behavior. [100][101][102] Introducing probiotics containing Lactobacillus in early stages of separation can ameliorate the effects of separation on HPA and reduce the corticosterone release.…”

Gutsy Moves: The Amygdala as a Critical Node in Microbiota to Brain Signaling

“…[90,96] Finally, different probiotic strains have been shown to reduce symptoms of anxiety and depression across several studies in clinical and healthy populations. [97,98] While there have also [5,9,10,88,90] Anxiolytic effects, sometimes sex-specific, in mice (light-dark box, elevated-plus maze) [72,113] Anxiolytic effects in mice (open field, defensive marble burying, elevated-plus maze, light-dark box) [91,93] Strain-specific anxiolytic effects in humans (e.g., Beck Anxiety Index, Hospital Anxiety & Depression Scale) and rodents (defensive marble burying, elevated-plus maze, open field) [11,62,133,134] Transplant from humans with depression or comorbid IBS and anxiety increases anxietylike behavior in mice (open field, step-down test, light-dark box) [96,125] Heightened anxiety in rats (open field) [89] Depression Increased depressive-like behavior in mice (forced swim) [90] Increased depressive-like behavior in rats (forced swim) [94] Antidepressant effects in mice and rats (forced swim, tail suspension, learned helplessness after inescapable shock) [91,92] Strain-specific antidepressant effects in humans (e.g. Beck Depression Inventory, Hospital Anxiety & Depression Scale) and rodents (tail suspension test, forced swim, sucrose preference) [11,97,98,133,134] Transplant from depressed human donors induces depressive-like behavior in mice (sucrose preference, forced swim [varied results], tail suspension test) [90,96] Learned fear Impaired fear recall in adult mice [101] Acute administration enhances fear extinction in rodents and exposure therapy in humans, [103,104] reduces fear recall in huma...…”

“…Like humans, rodents are naturally social animals, but GF rats and mice exhibit deficits in social behaviors such that they show less interest in social interaction and poorer memory for social partners. [89,[110][111][112] Deficits in social behavior are also observed following antibiotic-induced depletion of the microbiota. [72,113] The microbiota also plays a role in murine models of ASD, where treatment with specific bacteria has been shown to reverse many of the social deficits observed in these animals.…”

Impact of the gut microbiota on the neuroendocrine and behavioural responses to stress in rodents

“…Stressed GF rats exhibited a serum corticosterone concentration almost 3 times greater than stressed SPF rats, whereas no difference was observed between non-stressed GF and SPF rats. As shown in Figure 1, the dramatic difference in stressed rats was accompanied by an increase in the expression of the gene encoding the corticotropin releasing factor (CRF) in the hypothalamus, and by a decrease in the expression of the gene encoding the glucocorticoid receptor (GR) in the hippocampus of the GF rats (Crumeyrolle-Arias et al, 2014). These data indicate definitely that the gut microbiota regulates the HPA system.…”

“…Accordingly, we hypothesize that the gut microbiota has a buffering effect on the behavioural response to an acute stress. Presence of the gut microbiota tones down anxiety-like behaviour in strains genetically prone to anxiety but tones up the same behaviour in strains genetically less prone to anxiety (Crumeyrolle-Arias et al, 2014) (Fig. 3).…”