الفهرس 
OVERVIEW OF BIPOLAR DISORDEROnly 14 pages are availabe for public view
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Abstract
Bipolar disorder is a mental illness caused by a variety of factors. It is characterized by hidden early symptoms, long course of disease and poor prognosis in severe cases. Research on the etiology of BD has always been a hot issue in psychiatry. In recent years, important advances have been made in the biological role of gut microbiota in BD. Existing experiments provide evidence that one of the etiologies of BD is the disturbance of intestinal ecosystem, and the structural basis of the association between BD and the gut brain axis.
The relation between intestinal permeability and autoimmune diseases has been investigated in many studies, yet few studies have investigated the relation between intestinal permeability and BD using different biomarkers.
The principal pathways of the gut–brain axis include action through the vagus nerve, involving the endocrine system, the hypothalamic–pituitary–adrenal (HPA) axis, neurotransmitter pathways, metabolites, and immune system component.
Zonulaoccludens toxin (Zot) is an enterotoxin which is able to reversibly open intracellular tight junctions. Zot is able to interact with epithelial cells along the gastrointestinal tract with the highest binding in the jejunum and distal ileum. Given the complexity of the intracellular signaling activated by Zot leading to tight junction modulation, it was hypothesized that the toxin may mimic an endogenous protein which is able to regulate the epithelial tight junctions. Zonulin is a human analog to Zot. Ex vivo studies show endogenous human zonulin is able to increase permeability in both the jejunum and ileum.