The human gut microbiota is composed of trillions microorganisms with own gene. The gut microbes influence various aspect of Central nervous system through multiple mechanisms whereas vagus nerve connects the gut and brain by neural connections. To transmit signals they directly stimulate afferent neurons of the enteric nervous to the brain by vagus nerve. It is essential in alteration of neurotransmitter levels, if there is any disruption in the gut microbe it affect brain function, and finally it affects the neurological health sometimes it lead to disorders like leaky gut syndrome. They also play a key role in health issues which leads to depression, and disease like autism spectrum through activity of the gut-brain axis. The alteration in the bacterial composition guts microbiota lead to dysfunction of the digestive system such as bowl diseases, obesity, immune and neurological diseases. The gut microbes promote the digestion by facilitating the absorption of nutrients and also help the digestive system to function properly. Gut microbiome play defense role in the development of the immune system by creating a barrier against pathogens and toxins.

Keywords : Gut Microbiota, Homeostasis, Dysbiosis, Catecholamines, Neurogenerative, Vagus Nerve.