Effect of administration of young rats' plasma on depression-like behaviors, serotonin transporter, IDO enzyme expression levels, and apoptosis in the prefrontal cortex in a rat model of depression in old male animals

Abstract

With a wide variety of biological and behavioral changes, aging causes specific behavioral patterns that subsequently leads to the prevalence of mood and mental illnesses, including depression among the elderlies. In this study, we investigated the effects of intravenous injection of young rats’ plasma on depressive-like behaviors, apoptosis and neuroinflammation, IDO protein and related metabolites, serotonin transporter (SERT) and GAP-43 in the prefrontal cortex of depression model of aged rats. Materials and Methods: Twenty-four old (20-22 months) and eight young male Wistar rats (3 months) were randomly divided into four groups: young control rats (YC), old control rats (AC), old depression model rats (A+CUMS), and old depression model rats received young plasma (A+CUMS+YP). Depression was induced by chronic unpredictable mild stress (CUMS) paradigm. Young plasma was prepared from 30 young 3-month-old rats and injected 3 times per week for 4 weeks in A+CUMS+YP group. At the end of the study and after performing behavioral tests, the prefrontal region of the brain was isolated to measure molecular variables and also to evaluate the thickness of the gray matter in the study groups.

Results: Chronic stress induced depressive-like behaviors in the depression model groups. The results of this study showed that young plasma injection improved depressive-like behaviors in aged animal model, which was associated with decreased neuronal apoptosis, neuroinflammation, IDO expression, and Kynurenine levels, and increased expression of SERT and GAP-43 proteins in the prefrontal cortex.