Immature-like molecular expression patterns in the hippocampus of a mouse model of dementia with Lewy body-linked mutant β-synuclein

Aim: Maturation abnormalities of the brain cells have been suggested in several neuropsychiatric disorders, including schizophrenia, bipolar disorder, autism spectrum disorders, and epilepsy. In this study, we examined the expression patterns of neuronal maturation markers in the brain of a mouse model of dementia with Lewy body-linked mutant beta-synuclein (beta S), especially in the hippocampus, to explore whether such brain abnormalities occur in neurodegenerative disorders as well. Methods: Quantitative PCR (qPCR) and immunohistochemical analyses were performed using the hippocampus of 14-month-old P123H beta S transgenic (Tg) mice to evaluate the expression of molecular markers for maturation of dentate granule cells. Results: Based on qPCR results, expression of Tdo2 and Dsp (markers of mature granule cells) was decreased and that of Drd1a (a marker of immature granule cells) was increased in the hippocampus of P123H beta S Tg mice compared to that in wild-type controls. Immunohistochemical analysis revealed decreased expression of mature granule cell markers Calb1 and Gria1, along with increased expression of the microglial marker Iba1, in the hippocampal dentate gyrus region of P123H beta S Tg mice. P123H beta S Tg mice exhibited immature-like neuronal molecular expression patterns and microgliosis in the hippocampus. Pseudo-immaturity of dentate granule cells, associated with neuroinflammation, may be a shared endophenotype in the brains of at least a subgroup of patients with neuropsychiatric disorders and neurodegenerative diseases.