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[Display omitted] • IGF-1 gene therapy improves cognitive deficits caused by 6-hydroxydopamine. • IGF-1 gene therapy increases the expression level of tyrosine hydroxylase in the caudate-putamen. • IGF-1 gene therapy modifies parameters of microglia and astrocyte phenotypes. Cognitive impairment in Parkinson's disease is considered an indicator of the prodromal stages of this condition, occurring prior to the onset of classic and pathognomonic motor symptoms. Among other factors, neuroinflammation is increasingly recognized as a potential mediator of this neurodegenerative process, and glial cells are directly involved. However, the use of neurotrophic factors is associated with neuroprotection and cognitive improvements. Among all those factors, insulin-like growth factor 1 (IGF-1) has attracted considerable attention. In this study, we aimed to investigate the effect of IGF-1 gene therapy in an early animal model of 6-hydroxidopamine (6-OHDA)- induced parkinsonism. For this purpose, we employed male Wistar rats. The animals were first divided into two groups according to the bilateral injection into de Caudate Putamen unit (CPu):(a) VEH group (vehicle solution) and (b) 6-OHDA group (neurotoxic solution). After that, the animals in each group were divided, according to the bilateral injection into the dorsal hippocampus, in a control group (who received a control virus RAd-DSRed) and an experimental group (who received a therapeutic virus (RAd-IGF1). After three weeks of exposure to 6-OHDA, our study showed that IGF-1 gene therapy improved cognitive deficits related to short-term and spatial working memory, it also increased expression levels of tyrosine hydroxylase in the CPu. In addition, the therapy resulted in significant changes in several parameters (area, perimeter, roundness, ramification, and skeleton ́s analyses) related to microglia and astrocyte phenotypes, particularly in the CPu and dorsal hippocampal areas. Our data support the use of IGF-1 as a therapeutic molecule for future gene transfer interventions, that will contribute to a better understanding of the mechanisms correlating cognitive function and inflammatory process. [ABSTRACT FROM AUTHOR]

Growth factors, such as insulin‐like growth factor 1 (IGF‐1), among others are known for their critical involvement in learning and memory processes. IGF‐1 regulates cognitive functions, synapse density, neurotransmission, and adult neurogenesis and induces structural and synaptic plasticity‐specific changes. Although IGF‐1 has been suggested to participate in different memory processes, its role in memories associated with negative emotional experiences still remains to be elucidated. The principal aim of the present study was to test whether IGF‐1 overexpression using adenoviral vectors in basolateral amygdala (BLA) influences both the expression and formation of contextual fear memory, as well as the hippocampal structural plasticity associated with such memory trace. We found that IGF‐1 overexpression promotes the formation and expression of a specific contextual fear memory trace, and such effect persisted at least 7 days after recall. Moreover, the overexpression of this growth factor in BLA upregulates the activation of the ERK/MAPK pathway in this brain structure. In addition, intra‐BLA IGF‐1 overexpression causes dorsal hippocampus (DH) structural plasticity modifications promoting changes in the proportion of mature dendritic spines in the CA1 region, after a weak conditioning protocol. The present findings contribute to the knowledge underlying BLA‐DH trace memory of fear and reveal important new insights into the neurobiology and neurochemistry of fear acquisition modulated by IGF‐1 overexpression. The understanding of how IGF‐1 modulates the formation of a fear contextual trace may pave the way for the development of novel therapeutic strategies focused on fear, anxiety, and trauma‐related disorders. [ABSTRACT FROM AUTHOR]

It is well‐established that females live longer than males. Paradoxically, women tend to have poorer health, a condition often named sex frailty. The aim of this study was to evaluate possible frailty predictors in older mice in a sex‐specific manner, in order to employ these predictors to follow‐up therapy efficiency. To further evaluate therapy effects, we also investigated the use of neurotrophic insulin‐like growth factor 1 (IGF‐1) gene therapy and its correlation with the expression of this frailty and emotional behaviour. In order to evaluate frailty, we employed two different approaches. We performed a frailty assessment through a 31‐Item Clinical Frailty Index and through a Performance‐Based 8‐Item Frailty Index. Our results show that both indexes are in concordance to evaluate sex differences, but they do not correlate when evaluating IGF‐1 therapy effects. Moreover, in order to reduce test‐to‐test variability for measures of dependent variables, we compared open field results across studies assessing sex and treatment by means of the z‐score normalization. The data show that regular open field parameters submitted to z‐score normalization analysis could be a useful tool to identify sex differences in ageing mice after growth factor therapies. Taking this into account, sex is a factor that influences the incidence and/or nature of all major complex diseases; the main outcome of our investigation is the development of an efficient tool that compares the use of different frailty index calculations. This represents an important strategy in order to identify sex differences and therapy efficiency in ageing models. [ABSTRACT FROM AUTHOR]