BDNF and schizophrenia: Since the development of a healthy microbiome is essential for brain plasticity through the expression of N-methyl-D-aspartate (NMDA) and brain-derived neurotrophic factor (BDNF)/glial-cell derived neurotrophic factor (GDNF) receptors, it has been found that alteration in gut microbiota results in hypoactivity of these receptors, which have been studied in the schizophrenia patients [143,144].