Expression of BDNF and trkB in the hippocampus of a rat genetic model of vulnerability (Roman low-avoidance) and resistance (Roman high-avoidance) to stress-induced depression

摘要

Introduction: The selective breeding of Roman High- (RHA) and Low-Avoidance\ud(RLA) rats for, respectively, rapid versus poor acquisition of the active avoidance\udresponse has generated two distinct phenotypes differing in many behavioral\udtraits, including coping strategies to aversive conditions. Thus, RLA rats are considered\udas a genetic model of vulnerability to stress-induced depression whereas\udRHA rats are a model of resilience to that trait. Besides the monoamine hypothesis\udof depression, there is evidence that alterations in neuronal plasticity in the\udhippocampus and other brain areas are critically involved in the pathophysiology\udof mood disorders.\udMaterials and Methods: Western blot (WB) and immunohistochemistry were used to\udinvestigate the basal immunochemical occurrence of brain-derived neurotrophic factor\ud(BDNF) and its high-affinity tyrosine-kinase receptor trkB in the dorsal and ventral\udhippocampus of adult RHA and RLA rats.\udResults: WB analysis indicated that the optical density of BDNF- and trkB-positive\udbands in the dorsal hippocampus is, respectively, 48% and 25% lower in RLA versus\udRHA rats. Densitometric analysis of BDNF- and trkB-like immunoreactivity (LI) in brain\udsections showed that BDNF-LI is 24% to 34% lower in the different sectors of the\udAmmon’s horn of RLA versus RHA rats, whereas line-related differences are observed\udin the dentate gyrus (DG) only in the ventral hippocampus. As for trkB-LI, significant\uddifferences are observed only in the dorsal hippocampus, where density is 23% lower\udin the DG of RLA versus RHA rats, while no differences across lines occur in the\udAmmon’s horn.\udConclusion: These findings support the hypothesis that a reduced BDNF/trkB signaling\udin the hippocampus of RLA versus RHA rats may contribute to their more pronounced\udvulnerability to stress-induced depression.