Probes for CMS

Chronic stress represents a major contributor for the development of mental illness. This study aimed to investigate how animals exposed to chronic mild stress (CMS) responded to an acute stress (AS), as a vulnerability's challenge, and to establish the potential effects of the antipsychotic drug lurasidone on such mechanisms. Adult male Wistar rats were exposed or not (controls) to a CMS paradigm for 7 weeks. Starting from the end of week 2, animals were randomized to receive vehicle or lurasidone for 5 weeks. Sucrose intake was used to measure anhedonia. At the end, half of the animals were exposed to an acute stress before sacrifice. Exposure to CMS produced a significant reduction in sucrose consumption, whereas lurasidone progressively normalized such alteration. We found that exposure to AS produced an upregulation of Brain derived neurotrophic factor (Bdnf) in the prefrontal cortex of controls animals. This response was impaired in CMS rats and restored by lurasidone treatment. While in control animals, AS-induced increase of Bdnf mRNA levels was specific for Parvalbumin cells, CMS rats treated with lurasidone show a significant upregulation of Bdnf in pyramidal cells. Furthermore, when investigating the activation of different brain regions, CMS rats showed an impairment in the global response to the acute stressor, that was largely restored by lurasidone treatment. Our results suggest that lurasidone treatment in CMS rats may regulate specific circuits and mechanisms, which will ultimately contribute to boost resilience under stressful challenges.

Rationale: During neonatal heart regeneration, the fibrotic response, which is required to prevent cardiac rupture, resolves via poorly understood mechanisms. Deletion of the Hippo pathway gene Sav in adult CMs increases Yap activity and promotes cardiac regeneration, partly by inducing fibrosis resolution. Deletion of Yap in neonatal cardiomyocytes (CMs) leads to increased fibrosis and loss of neonatal heart regeneration, suggesting that Yap inhibits fibrosis by regulating intercellular signaling from CMs to cardiac fibroblasts (CFs). Objective: We investigated the role of Wntless (Wls), which is a direct target gene of Yap, in communication between CMs and CFs during neonatal heart regeneration. Methods and Results: We generated two mouse models to delete Wls specifically in CMs (Myh6-Cas9 combined with AAV9-Wls-gRNAs, and Myh6cre-ERT2/+; Wlsflox/flox mouse). Reanalysis of single-cell RNA-sequencing data revealed that Wnt ligands are expressed in CMs, whereas Wnt receptors are expressed in CFs, suggesting that Wnt signaling is directional from CMs to CFs during neonatal heart regeneration. Wls deletion in neonatal hearts disrupted Wnt signaling, showing as reduced noncanonical Wnt signaling in non-CMs. Four weeks after neonatal heart infarction, heart function was measured by echocardiography. Wls deletion in neonatal hearts after myocardial infarction impairs neonatal heart regeneration, marked by decreased contractile function and increased fibrosis. Wls mutant hearts display CF activation, characterized by increased extracellular matrix secretion, inflammation, and CF proliferation. Conclusions: These data indicate that during neonatal heart regeneration, intercellular signaling from CMs to CFs occurs via noncanonical Wnt signaling to rebuild cardiac architecture after myocardial infarction.

Background: Stress represents a major contributor for the development of mental illness. Accordingly, exposure of adult rats to chronic stress represents a valuable experimental tool to investigate the ability of pharmacological intervention to counteract the adverse effects produced by stress exposure. The aim of this study was to perform a time course analyses of the changes produced by the antipsychotic drug lurasidone in the Chronic Mild Stress (CMS) model, in order to identify early mechanisms that may contribute to its therapeutic activity. Methods: Adult male Wistar rats were left undisturbed or exposed to the CMS paradigm, a well-established model of depression. After two weeks of stress, both controls and CMS rats were randomly divided in two subgroups that received vehicle or lurasidone for five weeks. Sucrose consumption was used to measure anhedonia, a core symptom of depression. Animals were sacrificed after two, three or five weeks of treatment in order to investigate dynamic changes during lurasidone administration. For the sucrose consumption we performed three-way ANOVA and two-way ANOVA with Tukey's posthoc. For the molecular analysis we performed 2-way ANOVA, with Tukey's posthoc for qRT-PCR data and Sidak's posthoc for RNAscope data. Results: CMS rats show a significant reduction in sucrose consumption, (-46% after two weeks, p

Galanin receptor1 (GalR1) transcript levels are elevated in the rat ventral periaqueductal gray (vPAG) after chronic mild stress (CMS) and are related to depression-like behavior. To explore the mechanisms underlying the elevated GalR1 expression, we carried out molecular biological experiments in vitro and in animal behavioral experiments in vivo. It was found that a restricted upstream region of the GalR1 gene, from -250 to -220, harbors an E-box and plays a negative role in the GalR1 promoter activity. The transcription factor Scratch2 bound to the E-box to down-regulate GalR1 promoter activity and lower expression levels of the GalR1 gene. The expression of Scratch2 was significantly decreased in the vPAG of CMS rats. Importantly, local knockdown of Scratch2 in the vPAG caused elevated expression of GalR1 in the same region, as well as depression-like behaviors. RNAscope analysis revealed that GalR1 mRNA is expressed together with Scratch2 in both GABA and glutamate neurons. Taking these data together, our study further supports the involvement of GalR1 in mood control and suggests a role for Scratch2 as a regulator of depression-like behavior by repressing the GalR1 gene in the vPAG.