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Chronic stress induces activity, synaptic and transcriptional remodeling of the lateral habenula associated with deficits in motivated behaviors

ABSTRACT: Chronic stress (CMS) affects many brain functions and is a major risk factor for the development of depression. Here, we demonstrate that CMS-induced hyperactivity in VTA-projecting lateral habenula (LHb) neurons is associated with increased passive coping (PC) but not anxiety or anhedonia. LHb→VTA neurons in mice with increased PC show increased burst and tonic firing as well as synaptic adaptations in excitatory inputs from the entopeduncular nucleus (EP). In-vivo manipulations of EP→LHb or LHb→VTA neurons selectively alter PC and effort-related motivation. Conversely, dorsal raphe (DR)-projecting LHb neurons do not show CMS-induced hyperactivity and are targeted indirectly by the EP. Using single-cell transcriptomics we reveal a set of genes that can collectively serve as biomarkers to identify mice with increased PC and differentiate LHb→VTA from LHb→DR neurons. Together, we provide a set of biological markers at the level of genes, synapses, cells and circuits that define a distinctive CMS-induced behavioral phenotype.

ORGANISM(S): Mus musculus

PROVIDER: GSE136723 | GEO | 2019/09/16

REPOSITORIES: GEO

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Project description:Background: Vitamin D deficiency is associated with cardiac hypertrophy and heart failure, and vitamin D therapy prevents the progression of cardiac hypertrophy in animal models. Here, we examine whether vitamin D therapy regresses pre-existing cardiac hypertrophy, and prevents the progression to heart failure. Methods and Results: When male Dahl salt-sensitive (DSS) rats are fed a high salt (HS) diet, all rats develop cardiac hypertrophy after 5 weeks (H). Thereafter, rats were treated with vehicle (V), paricalcitol (PC, an active vitamin D analog at 200ng, IP 3x/wk), enalapril (EP, 90ug/day), and PC+EP. All groups were continued on the HS diet and evaluated after 4 weeks of therapy. The PC and PC+EP, but not the V and EP-only groups, showed significant regression of pre-existing cardiac hypertrophy. The signs of decompensated heart failure were evident in the vehicle-treated group; these heart failure parameters significantly improved with PC, EP or PC+EP therapy. The expression of PKCe, which is regulated by Ca2+ and known to stimulate cardiac hypertrophy, was significantly increased in the vehicle group, and PC, EP or PC+EP effectively decreased PKCe activation. We also observed normalization of genetic alterations during progression to heart failure with PC treatment. Conclusions: PC treatment resulted in both the regression of pre-existing cardiac hypertrophy, and the attenuation of the progression to heart failure, compared to improvement in progression to heart failure by EP alone. These beneficial findings in the heart were associated with inhibition of PKCe activation, and reversal of gene alterations. Male Dahl salt-sensitive rats (Harlan Sprague–Dawley, Somerville, NJ) were bred and fed a normal diet until 6 weeks of age. To generate pressure overload cardiac hypertrophy, they were then fed a high salt (6%NaCl) diet for the next 5 weeks. Data for baseline hypertrophic group (H) was obtained at the end of 11 weeks. Among H group animals, they were divided as follows and treated for an additional 4 weeks: 1) continuation of the HS diet with vehicle injection (H+V); 2) continuation of the HS diet with paricalcitol (19-nor-1,25-(OH)2 D2) (PC) (200ng IP 3x/wk) injection (H+PC); 3) continuation of the HS diet with low dose enalapril (EP), an angiotensin-converting enzyme inhibitor, infusion via osmotic pump and vehicle injection (H+EP+V); and 4) continuation of the HS diet with low dose EP infusion via osmotic pump and PC (200ng IP 3x/wk) injection (H+EP+PC). PC was prepared with 95% propylene glycol and 5% ethyl alcohol solution and administered three times a week on Monday, Wednesday, and Friday for 4 consecutive weeks. Vehicle groups received vehicle injections on the same schedule. Two groups of rats were implanted with pumps to deliver EP for 4 weeks. Since the reduction in blood pressure (BP) from high doses of EP would have effects on cardiac hypertrophy and progression to heart failure, we used low dose EP at 90ug/day, a maximum dose that did not significantly decrease BP in these rats, to study the effects of EP and PC that are independent of BP.

Project description:Implications for neuroprotection in Parkinson's disease Parkinson’s disease and its characteristic symptoms are thought to arise from the progressive degeneration of specific midbrain dopamine (DA) neurons. In humans, DA neurons of the substantia nigra (SN) and their projections to the striatum show selective vulnerability, while neighboring DA neurons of the ventral tegmental area (VTA) are relatively spared from degeneration. This pattern of cell loss is mimicked in humans, primates, and certain rodents by the neurotoxin MPTP. In this study, we aimed to test the hypothesis that there are factors in the VTA that are potentially neuroprotective against MPTP and that these factors change over time. We have found a differential transcriptional response within the cells of the SN and VTA to sustained exposure to a low dose of MPTP. Specifically, the VTA has increased expression of 148 genes as an early response to MPTP and 113 genes as a late response to MPTP toxicity. This response encompasses many areas of cellular function, including protein regulation (Phf6) and ion/metal regulation (PANK2, Car4). Notably, these responses were largely absent from the cells of the SN. Our data show a clear dynamic response in maintaining the homeostasis and viability of the neurons in the VTA that is lacking in the SN after neurotoxin challenge. We used microarrays to analyze the differential response of the substantia nigra (SN) and ventral tegmental area (VTA) to a chronic low dose of the neurotoxin MPTP. Transgenic hTH-GFP mice were treated with MPTP (4mg/kg) for either 2 or 10 days. Control mice were given an equal volume of saline for 10 days. Dopamine neurons from the substantia nigra and ventral tegmental areas of control and MPTP treated animals were laser captured. The RNA was isolated and processed for microarray hybridization. Each group had three biological replicates, for a total of 18 samples. Three each in the following: Control SN, Control VTA, 2 day MPTP SN, 2 day MPTP VTA, 10 day MPTP SN, 10 day MPTP VTA. Samples were log2 transformed and RMA normalized using Agilent Genespring 10.0 GX.

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Chronic stress induces activity, synaptic and transcriptional remodeling of the lateral habenula associated with deficits in motivated behaviors

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