Over 100 years ago, Nobel laureate Elie Metchnikoff proposed that lactic acid bacteria are beneficial to human health. Since then, and most recently through technological advances in DNA sequencing, RNA sequencing, and metabolomics, we have come to realize that these microbes are part of complex multicellular communities that collectively constitute the gut microbiota.
Every report, experiment and discussions until this date about brain behaviour & environment are placed within the Neuroscience Journal.
All in all, the relationship between the gut microbiota and the host provides beneficial effects by helping with digestion of food, energy storage, and modulation and protection of the intestinal barrier.
The activity of microorganisms present in the intestinal microbiota also influences the intestinal immune system, which is linked to the nervous system.
According to recent studies in rodents and humans, most of which were association studies, modifications in microbial diversity are linked to negative health outcomes like autism spectrum disorders, depression, and anxiety. The detailed Microbiology Journal contains all the book reviews, studies, papers, research paper etc about microbiology & infection that is accessible to everyone online.
Overview of the Gut-Brain Axis
The enteric nervous system (ENS) is composed of millions of neurons, which are present in the mucosa of the gastrointestinal tract. These neurons are responsible for balancing intestinal functions.
The most direct communication between the gut and brain is mediated by the vagus nerve. This nerve serves as a major pathway for the transmission of signals originating from the foregut and colon and is responsible for primary parasympathetic control, such as basic intestinal activities.
Autism Spectrum Disorders
Several studies have reported links between the microbiota composition and ASD. ASD are a group of developmental disorders associated with a range of behavioural deficits. Individuals with ASD show alterations in brain development and exhibit characteristic symptoms such as difficulty communicating, social development alterations, repetitive behaviours, and gastrointestinal disturbances. Apart from the role of genetic alterations, the causes of ASD are not well established.
Alzheimer’s Disease is a neurodegenerative disorder with complex etiologies that are still poorly understood. The severe cognitive impairments associated with AD correlate with the accumulation of protein aggregates composed of amyloid plaques and tau protein tangles in tissues of the CNS. Growing evidence suggests that microbial infections targeting the CNS constitute additional factors associated with an increased incidence of AD.
PD is a neurodegenerative motor disorder that affects an estimated 1 million people and 1% of the United States population > 60 years of age. PD is commonly associated with impaired gastric motility and elevated levels of alpha-synuclein in the intestine. The diagnosis of PD relies on a basic symptom, motor difficulty. This debilitation is caused by a decrease in dopamine and the subsequent death of the dopaminergic neurons in the substantia nigra.
Depression, the most common mental disorder, is a multifactorial disease that can result from biological, psychological, and social factors. Although its aetiology is not well understood, depression has been correlated with the individual’s stress levels and lifestyle, but can also be induced by anxiety and chronic diseases.
Symptoms include depressed mood, lack of inclination for daily activities, decreased appetite, and altered sleep and libido; severe depression is directly linked to self-harm and suicide.
According to the American Psychiatric Association, anxiety disorder is characterized by behavioural disturbances, phobia, and panic syndrome, as well as fear. Anxiety can also be understood as social phobia, which consists of fear in social situations that interferes directly with social conviviality.
Over the years, many studies have found correlations between the gut microbiota and the CNS. The points at which these studies intersect constitute the new field of neuromicrobiology.
Although it is clear that the gut microbiome plays a significant role in the health and disease states of the host. It remains to be elucidated whether these links are causative, promoting disease, or are, rather, the consequence of unrelated pathophysiology.