Human-fecal microbiota transplantation in relation to gut microbiome signatures in animal models for schizophrenia: A scoping review

More recently, attention has turned to the putative role of gut microbiome (GMB) in pathogenesis, symptomatology, treatment response and/or resistance in schizophrenia (SCZ). It is foreseeable that fecal microbiota transplantation (FMT) from SCZ patients (SCZ-FMT) to germ-free mice could represent a suitable experimental framework for a better understanding of the relationship between GMB and SCZ. Thus, we set out to identify literature (i) characterizing the GMB in animal models of SCZ, and (ii) employing SCZ-FMT into rodents to model SCZ in relation to behavioral and molecular phenotypes. Five studies examining animal models of SCZ suggest distinct GMB composition compared to respective control groups, which was correlated with SCZ-like behavioral phenotypes. Four additional studies investigated SCZ-FMT into rodents in relation to behavioral phenotypes, including spontaneous hyperlocomotion, social deficits, exaggerated startle response, and cognitive impairments, resembling those observed in SCZ patients. Mice receiving SCZ-FMT showed altered neurochemical and metabolic pathways in the brain. Animal models of SCZ have shown altered GMB composition, whereas reported behavioral and neurochemical alterations following FMT from patients into rodents suggest early face and construct validity for SCZ-FMT animal models. However, the predictive validity of these models remains to be validated.