The consumption of caffeine (an adenosine receptor antagonist) correlates inversely with depression and memory deterioration, and adenosine A 2A receptor (A 2A R) antagonists emerge as candidate therapeutic targets because they control aberrant synaptic plasticity and afford neuroprotection. Therefore we tested the ability of A 2A R to control the behavioral, electrophysiological, and neurochemical modifications caused by chronic unpredictable stress (CUS), which alters hippocampal circuits, dampens mood and memory performance, and enhances susceptibility to depression. CUS for 3 wk in adult mice induced anxiogenic and helpless-like behavior and decreased memory performance. These behavioral changes were accompanied by synaptic alterations, typified by a decrease in synaptic plasticity and a reduced density of synaptic proteins (synaptosomal-associated protein 25, syntaxin, and vesicular glutamate transporter type 1), together with an increased density of A 2A R in glutamatergic terminals in the hippocampus. Except for anxiety, for which results were mixed, CUS-induced behavioral and synaptic alterations were prevented by (i) caffeine (1 g/L in the drinking water, starting 3 wk before and continued throughout CUS); (ii) the selective A 2A R antagonist KW6002 (3 mg/kg, p.o.); (iii) global A 2A R deletion; and (iv) selective A 2A R deletion in forebrain neurons. Notably, A 2A R blockade was not only prophylactic but also therapeutically efficacious, because a 3-wk treatment with the A 2A R antagonist SCH58261 (0.1 mg/kg, i.p.) reversed the mood and synaptic dysfunction caused by CUS. These results herald a key role for synaptic A 2A R in the control of chronic stress-induced modifications and suggest A 2A R as candidate targets to alleviate the consequences of chronic stress on brain function.R epeated stress elicits neurochemical and morphological changes that negatively affect brain functioning (1, 2). Thus, repeated stress is a trigger or a risk factor for neuropsychiatric disorders, namely depression, in both humans and animal models (2, 3). Given the absence of effective therapeutic tools, novel strategies to manage the impact of chronic stress are needed, and analyzing particular lifestyles can provide important leads. Notably, caffeine consumption increases in stressful conditions (4) and correlates inversely with the incidence of depression (5, 6) and the risk of suicide (7,8). However, the molecular targets operated by caffeine to afford these beneficial effects have not been defined.Caffeine is the most widely consumed psychoactive drug. The only molecular targets for caffeine at nontoxic doses are the main adenosine receptors in the brain, namely the inhibitory A 1 receptors (A 1 R) and the facilitatory A 2A receptors (A 2A R) (9). A 2A R blockade affords robust protection against noxious brain conditions (10), an effect that might result from the ability of neuronal A 2A R to control aberrant plasticity (11, 12) and synaptotoxicity (13-15) or from A 2A R's impact on astrocytes (16) or microglia (17). T...
With molecular treatments coming into reach for spinocerebellar ataxia type 3 ( SCA 3), easily accessible, cross‐species validated biomarkers for human and preclinical trials are warranted, particularly for the preataxic disease stage. We assessed serum levels of neurofilament light (NfL) and phosphorylated neurofilament heavy ( pNfH ) in ataxic and preataxic subjects of two independent multicentric SCA 3 cohorts and in a SCA 3 knock‐in mouse model. Ataxic SCA 3 subjects showed increased levels of both NfL and pNfH . In preataxic subjects, NfL levels increased with proximity to the individual expected onset of ataxia, with significant NfL elevations already 7.5 years before onset. Cross‐sectional NfL levels correlated with both disease severity and longitudinal disease progression. Blood NfL and pNfH increases in human SCA 3 were each paralleled by similar changes in SCA 3 knock‐in mice, here also starting already at the presymptomatic stage, closely following ataxin‐3 aggregation and preceding Purkinje cell loss in the brain. Blood neurofilaments, particularly NfL, might thus provide easily accessible, cross‐species validated biomarkers in both ataxic and preataxic SCA 3, associated with earliest neuropathological changes, and serve as progression, proximity‐to‐onset and, potentially, treatment‐response markers in both human and preclinical SCA3 trials.
Aging is characterized by autophagy impairment that contributes to age-related disease aggravation. Moreover, it was described that the hypothalamus is a critical brain area for whole-body aging development and has impact on lifespan. Neuropeptide Y (NPY) is one of the major neuropeptides present in the hypothalamus, and it has been shown that, in aged animals, the hypothalamic NPY levels decrease. Because caloric restriction (CR) delays aging, at least in part, by stimulating autophagy, and also increases hypothalamic NPY levels, we hypothesized that NPY could have a relevant role on autophagy modulation in the hypothalamus. Therefore, the aim of this study was to investigate the role of NPY on autophagy in the hypothalamus. Using both hypothalamic neuronal in vitro models and mice overexpressing NPY in the hypothalamus, we observed that NPY stimulates autophagy in the hypothalamus. Mechanistically, in rodent hypothalamic neurons, NPY increases autophagy through the activation of NPY Y 1 and Y 5 receptors, and this effect is tightly associated with the concerted activation of PI3K, MEK/ERK, and PKA signaling pathways. Modulation of hypothalamic NPY levels may be considered a potential strategy to produce protective effects against hypothalamic impairments associated with age and to delay aging.ging is associated with accumulation of specific cellular proteins within neurons, a pathologic hallmark of many neurodegenerative diseases. Because average human life expectancy has increased, but also the prevalence of cognitive decline and dementia, aging research is now focused in finding strategies that increase both lifespan and healthspan.Autophagy is a highly regulated intracellular process involved in the turnover of most cellular constituents and in the maintenance of cellular homeostasis (1, 2). It is well described that basal autophagic activity decreases with age, contributing to the accumulation of altered macromolecules (3). In addition, autophagy impairment contributes to different aspects of aging phenotype and to aggravation of age-related diseases (4).Caloric restriction (CR), the reduced intake of calories without malnutrition, extends lifespan of many organisms, from yeast to mammals, and delays the progression of age-related diseases, at least in part, by stimulating autophagy (5-8). One major neuroendocrine effect of CR is the increase of neuropeptide Y (NPY) in the hypothalamus (9-12). The hypothalamus has a key role in the control of body homeostasis, neuroendocrine outputs, and feeding behavior. Recently, it was described that this brain area is critical for the development of whole-body aging and has impact on lifespan (13,14). In the hypothalamus, NPY is involved in the regulation of different physiological functions, such as regulation of food intake, body temperature, circadian rhythms, memory processing, and cognition (15-19). These diverse actions of NPY are mediated by G protein-coupled receptor subtypes named NPY Y 1 , Y 2 , Y 4 , and/or Y 5 (20, 21), all of which have been reported to be...
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractDepression is a worldwide disability disease associated with high morbidity and has increased dramatically in the last few years. The differential diagnosis and the definition of an individualized therapy for Depression is hampered by the absence of specific biomarkers. The aim of this study was to evaluate the phospholipdiomic profile of brain and myocardium in a mouse model of depression induced by chronic unpredictable stress. The lipidomic profile was evaluated by thin layer and liquid chromatography and mass spectrometry and lipid oxidation was estimated by FOX II assay. Antioxidant enzymes activity and the GSH/GSSG ratio were also evaluated.Results showed that chronic stress affect primarily the lipid profile of the brain, inducing an increased in lipid hydroperoxides, which was not detected in the myocardium. A significant decrease in phospahtidylinositol (PI) and in cardiolipin (CL) relative contents and also oxidation of cardiolipin and significant increase of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were observed in in brain from mice after unpredictable chronic stress conditions. In myocardium only an increase in PC content was observed. Nevertheless, both organs present a decreased GSH/GSSG ratio when compared to control groups, corroborating the occurrence of oxidative stress. The enzyme activities CAT and SOD were found to be decreased in the myocardium and increased in the brain, while glutathione reductase (GR) was decreased in brain. Our results indicate that in a mouse model for studying depression induced by chronic unpredictable stress, the modification of the expression of oxidative stress related enzymes did not prevent lipid oxidation in organs, particularly in the brain. These observations suggest that depression has an impact in the brain lipidome and that further studies are needed to better understand lipid role in depression and to evaluate their potential as future biomarkers.3
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