Gut microbiota modulate neurobehavior through changes in brain insulin sensitivity and metabolism

Area of Science:

• Neuroscience
• Microbiology
• Metabolic disorders

Background:

• Obesity and diabetes are linked to higher rates of anxiety and depression in humans.
• The gut microbiome's role and brain insulin resistance in these conditions are not fully understood.

Purpose of the Study:

• To investigate how gut microbiota changes affect brain insulin signaling and neurobehaviors in diet-induced obesity (DIO).
• To determine if antibiotic treatment can reverse anxiety and depression-like behaviors in DIO mice.

Main Methods:

• Diet-induced obesity (DIO) mouse model with and without antibiotic treatment (metronidazole or vancomycin).
• Behavioral tests for anxiety and depression.
• Analysis of insulin signaling and inflammation in brain regions (nucleus accumbens, amygdala).
• Metabolite profiling (tryptophan, GABA, BDNF, acylcarnitines) and fecal microbiota transplant.

Main Results:

• DIO mice exhibited increased anxiety and depression behaviors, linked to impaired brain insulin signaling and heightened inflammation.
• Antibiotic treatment normalized brain insulin signaling, reduced inflammation, and alleviated anxiety and depression-like behaviors.
• Observed changes in neurochemical metabolites and successful transfer of these effects via fecal transplant to germ-free mice.

Conclusions:

• Gut microbiota composition significantly impacts brain insulin signaling and metabolite levels.
• Modulating the gut microbiome through antibiotics can ameliorate neurobehavioral deficits associated with obesity.
• Targeting the gut-brain axis offers a potential therapeutic strategy for obesity-related anxiety and depression.