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Mouse repeated electroconvulsive seizure (ECS) does not reverse social stress effects but does induce behavioral and hippocampal changes relevant to electroconvulsive therapy (ECT) side-effects in the treatment of depression.

ABSTRACT: Electroconvulsive therapy (ECT) is an effective treatment for depression, but can have negative side effects including amnesia. The mechanisms of action underlying both the antidepressant and side effects of ECT are not well understood. An equivalent manipulation that is conducted in experimental animals is electroconvulsive seizure (ECS). Rodent studies have provided valuable insights into potential mechanisms underlying the antidepressant and side effects of ECT. However, relatively few studies have investigated the effects of ECS in animal models with a depression-relevant manipulation such as chronic stress. In the present study, mice were first exposed to chronic social stress (CSS) or a control procedure for 15 days followed by ECS or a sham procedure for 10 days. Behavioral effects were investigated using an auditory fear conditioning (learning) and expression (memory) test and a treadmill-running fatigue test. Thereafter, immunohistochemistry was conducted on brain material using the microglial marker Iba-1 and the cholinergic fibre marker ChAT. CSS did not increase fear learning and memory in the present experimental design; in both the control and CSS mice ECS reduced fear learning and fear memory expression. CSS induced the expected fatigue-like effect in the treadmill-running test; ECS induced increased fatigue in CSS and control mice. In CSS and control mice ECS induced inflammation in hippocampus in terms of increased expression of Iba-1 in radiatum of CA1 and CA3. CSS and ECS both reduced acetylcholine function in hippocampus as indicated by decreased expression of ChAT in several hippocampal sub-regions. Therefore, CSS increased fatigue and reduced hippocampal ChAT activity and, rather than reversing these effects, a repeated ECS regimen resulted in impaired fear learning-memory, increased fatigue, increased hippocampal Iba-1 expression, and decreased hippocampal ChAT expression. As such, the current model does not provide insights into the mechanism of ECT antidepressant function but does provide evidence for pathophysiological mechanisms that might contribute to important ECT side-effects.

SUBMITTER: van Buel EM

PROVIDER: S-EPMC5598988 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Rationale Electroconvulsive seizure (ECS) therapy is a nonchemical treatment for depression. Since ECS up-regulates expression of c-Fos in the paraventricular nucleus of hypothalamus (PVN), the function of which is frequently influenced in depression, we hypothesized that ECS modulates functions of the PVN and contributes to its antidepressant effects. Objectives To identify gene expression changes in the mouse PVN by ECS treatment Material and methods First, we established a method to amplify nucleotides from small quantities of RNA. Mice received one shock of ECS and their brains were collected at 2 or 6 h after shock. The PVN was microdissected from dehydrated brain sections, its total RNA was extracted and microarray analysis was applied. Results At 2 h after ECS, 2.6% (589 genes) of the probes showed more than 2-fold decrease, and 0.9% (205 genes) showed more than 2-fold increase. To confirm the expression changes, genes showing differential expression with a wide range in the microarray were analyzed by qPCR. Among the genes with more than 2-fold change by ECS, down-regulated 94 genes and up-regulated 24 genes have been reported the association with anxiety, bipolar disorder or mood disorder by the Ingenuity knowledge database. The groups of down-regulated genes, which are suggested to modulate the function of the PVN or associate to psychiatric disorders, include neuropeptides (Cck), kinases (Prkcb, Prkcc, Camk2a), transcription factors (Bcl6, Tbr1), transporters (Aqp4) and others (Fmr1). Conclusion The present results indicate that ECS treatment can modulate the functions of PVN via a series of gene expression changes, and may contribute to its antidepressant effects at least in part. Mice received one shock of ECS and their brains were collected at 2 h (PVN_ECS2h_1, PVN_ECS2h_2) or 6 h after shock (PVN_ECS6h_1, PVN_ECS6h_2). The brains of sham-treated animals were collected at 2 h after treatment (PVN_sham_1, PVN_sham_2). The PVN was microdissected from dehydrated brain sections, and its total RNA was extracted. RNA samples from two or three animals were pooled to minimize the impact of biological variance. After nucleotide amplification by the ovation amplification, the gene expression profiles were obtained by the Affymetrix microarray analysis. The microarray analysis was performed twice using different sets of animals.

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Mouse repeated electroconvulsive seizure (ECS) does not reverse social stress effects but does induce behavioral and hippocampal changes relevant to electroconvulsive therapy (ECT) side-effects in the treatment of depression.

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