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BACKGROUND: Milk-fat globule membrane (MFGM) is a complex structure secreted by the mammary gland and present in mammalian milk. MFGM contains lipids and glycoproteins as well as gangliosides, which may be involved in myelination processes. Notably, myelination and thereby white matter integrity are often altered in obesity. Furthermore, MFGM interventions showed beneficial effects in obesity by affecting inflammatory processes and the microbiome. In this study, we investigated the impact of a dietary MFGM intervention on fat storage, neuroinflammatory processes and myelination in a rodent model of high fat diet (HFD)-induced obesity. METHODS: 12-week-old male low density lipoprotein receptor-deficient Leiden mice were exposed to a HFD, a HFD enriched with 3% whey protein lipid concentrate (WPC) high in MFGM components, or a low fat diet. The impact of MFGM supplementation during 24-weeks of HFD-feeding was examined over time by analyzing body weight and fat storage, assessing cognitive tasks and MRI scanning, analyzing myelinization with polarized light imaging and examining neuroinflammation using immunohistochemistry. RESULTS: We found in this study that 24 weeks of HFD-feeding induced excessive fat storage, increased systolic blood pressure, altered white matter integrity, decreased functional connectivity, induced neuroinflammation and impaired spatial memory. Notably, supplementation with 3% WPC high in MFGM components restored HFD-induced neuroinflammation and attenuated the reduction in hippocampal-dependent spatial memory and hippocampal functional connectivity. CONCLUSIONS: We showed that supplementation with WPC high in MFGM components beneficially contributed to hippocampal-dependent spatial memory, functional connectivity in the hippocampus and anti-inflammatory processes in HFD-induced obesity in rodents. Current knowledge regarding exact biological mechanisms underlying these effects should be addressed in future studies.
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Dieta Hiperlipídica , Glicolipídeos/farmacologia , Glicoproteínas/farmacologia , Obesidade/complicações , Animais , Modelos Animais de Doenças , Glicolipídeos/metabolismo , Glicoproteínas/metabolismo , Gotículas Lipídicas/metabolismo , Masculino , Camundongos , Camundongos Obesos , Neuropatologia/métodos , Neuropatologia/estatística & dados numéricos , Obesidade/epidemiologia , Obesidade/metabolismoRESUMO
Objectives: Ghrelin acts on a variety of central- and peripheral organs causing an orexigenic effect, conclusively followed by increased caloric intake. Recent studies have indicated that ghrelin's function as an orexigenic agent does not entirely reflect the full functional properties of the peptide. Specifically, ghrelin regulates stress-hormone synthesis and secretion therewith affecting the stress-axis. The role of stress in the development of obesity has been extensively studied. However, the orexigenic and underlying stress-regulatory effect of ghrelin has not yet been further considered in the development of stress-induced obesity.Methods: Therefore, this review aims to accentuate the potential of ghrelin as a factor in the pathological development of stress-induced obesity.Results: In this review we discuss (1) the ghrelin-mediated intracellular cascades and elucidate the overall bioactivation of the peptide, and (2) the mechanisms of ghrelin signalling and regulation within the central nervous system and the gastro-intestinal system.Discussion: These biological processes will be ultimately discussed in relation to the pathogenesis of stress-induced obesity.
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Grelina/metabolismo , Obesidade/metabolismo , Animais , Humanos , Receptores de Grelina , Transdução de Sinais , Estresse FisiológicoRESUMO
Antidepressants have been shown to influence mitochondrial function directly, and suboptimal mitochondrial function (SMF) has been implicated in complex psychiatric disorders. In the current study, we used a mouse model for trait SMF to test the hypothesis that chronic fluoxetine treatment in mice subjected to chronic stress would negatively impact brain bioenergetics, a response that would be more pronounced in mice with trait SMF. In contrast, we hypothesized that chronic ketamine treatment would positively impact mitochondrial function in both WT and mice with SMF. We used an animal model for trait SMF, the Ndufs4GT/GT mice, which exhibit 25% lower mitochondrial complex I activity. In addition to antidepressant treatment, mice were subjected to chronic unpredictable stress (CUS). This paradigm is widely used to model complex behaviours expressed in various psychiatric disorders. We assayed several physiological indices as proxies for the impact of chronic stress and antidepressant treatment. Furthermore, we measured brain mitochondrial complex activities using clinically validated assays as well as established metabolic signatures using targeted metabolomics. As hypothesized, we found evidence that chronic fluoxetine treatment negatively impacted brain bioenergetics. This phenotype was, however, not further exacerbated in mice with trait SMF. Ketamine did not have a significant influence on brain mitochondrial function in either genotype. Here we report that trait SMF could be a moderator for an individual's response to antidepressant treatment. Based on these results, we propose that in individuals with SMF and comorbid psychopathology, fluoxetine should be avoided, whereas ketamine could be a safer choice of treatment.
Assuntos
Fluoxetina , Ketamina , Animais , Encéfalo/metabolismo , Modelos Animais de Doenças , Complexo I de Transporte de Elétrons/metabolismo , Fluoxetina/farmacologia , Homeostase , Ketamina/toxicidade , Camundongos , Mitocôndrias , Fenótipo , Estresse Psicológico/tratamento farmacológicoRESUMO
The obesity epidemic increases the interest to elucidate impact of short-chain fatty acids on metabolism, obesity, and the brain. We investigated the effects of propionic acid (PA) and caproic acid (CA) on metabolic risk factors, liver and adipose tissue pathology, brain function, structure (by MRI), and gene expression, during obesity development in Ldlr-/- .Leiden mice. Ldlr-/- .Leiden mice received 16 weeks either a high-fat diet (HFD) to induce obesity, or chow as reference group. Next, obese HFD-fed mice were treated 12 weeks with (a) HFD + CA (CA), (b) HFD + PA (PA), or (c) a HFD-control group. PA reduced the body weight and systolic blood pressure, lowered fasting insulin levels, and reduced HFD-induced liver macrovesicular steatosis, hypertrophy, inflammation, and collagen content. PA increased the amount of glucose transporter type 1-positive cerebral blood vessels, reverted cerebral vasoreactivity, and HFD-induced effects in microstructural gray and white matter integrity of optic tract, and somatosensory and visual cortex. PA and CA also reverted HFD-induced effects in functional connectivity between visual and auditory cortex. However, PA mice were more anxious in open field, and showed reduced activity of synaptogenesis and glutamate regulators in hippocampus. Therefore, PA treatment should be used with caution even though positive metabolic, (cerebro) vascular, and brain structural and functional effects were observed.
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Caproatos/farmacologia , Transtornos Cerebrovasculares/prevenção & controle , Inflamação/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Obesidade/complicações , Propionatos/farmacologia , Receptores de LDL/fisiologia , Animais , Transtornos Cerebrovasculares/etiologia , Transtornos Cerebrovasculares/metabolismo , Transtornos Cerebrovasculares/patologia , Dieta com Restrição de Gorduras/efeitos adversos , Dieta Hiperlipídica/efeitos adversos , Inflamação/metabolismo , Inflamação/patologia , Masculino , Camundongos , Camundongos Knockout , Camundongos Obesos , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/patologiaRESUMO
BACKGROUND: Altered levels of urocortin 1 (Ucn1) in the centrally projecting Edinger-Westphal nucleus (EWcp) of depressed suicide attempters or completers mediate the brain's response to stress, while the mechanism regulating Ucn1 expression is unknown. We tested the hypothesis that microRNAs (miRNAs), which are vital fine-tuners of gene expression during the brain's response to stress, have the capacity to modulate Ucn1 expression. METHODS: Computational analysis revealed that the Ucn1 3' untranslated region contained a conserved binding site for miR-326. We examined miR-326 and Ucn1 levels in the EWcp of depressed suicide completers. In addition, we evaluated miR-326 and Ucn1 levels in the serum and the EWcp of a chronic variable mild stress (CVMS) rat model of behavioural despair and after recovery from CVMS, respectively. Gain and loss of miR-326 function experiments examined the regulation of Ucn1 by this miRNA in cultured midbrain neurons. RESULTS: We found reduced miR-326 levels concomitant with elevated Ucn1 levels in the EWcp of depressed suicide completers as well as in the EWcp of CVMS rats. In CVMS rats fully recovered from stress, both serum and EWcp miR-326 levels rebounded to nonstressed levels. While downregulation of miR-326 levels in primary midbrain neurons enhanced Ucn1 expression levels, miR-326 overexpression selectively reduced the levels of this neuropeptide. LIMITATIONS: This study lacked experiments showing that in vivo alteration of miR-326 levels alleviate depression-like behaviours. We show only correlative data for miR-325 and cocaine- and amphetamine-regulated transcript levels in the EWcp. CONCLUSION: We identified miR-326 dysregulation in depressed suicide completers and characterized this miRNA as an upstream regulator of the Ucn1 neuropeptide expression in midbrain neurons.
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Transtorno Depressivo/metabolismo , Mesencéfalo/metabolismo , MicroRNAs/metabolismo , Urocortinas/metabolismo , Adulto , Animais , Sítios de Ligação , Células Cultivadas , Doença Crônica , Simulação por Computador , Modelos Animais de Doenças , Regulação para Baixo , Humanos , Masculino , Pessoa de Meia-Idade , Neurônios/metabolismo , RNA Mensageiro/metabolismo , Ratos Wistar , Estresse Psicológico , SuicídioRESUMO
White matter hyperintensities (WMH) are the most prevalent markers of cerebral small vessel disease (SVD), which is the major vascular risk factor for dementia. Microvascular pathology and neuroinflammation are suggested to drive the transition from normal-appearing white matter (NAWM) to WMH, particularly in individuals with hypertension. However, current imaging techniques cannot capture ongoing NAWM changes. The transition from NAWM into WMH is a continuous process, yet white matter lesions are often examined dichotomously, which may explain their underlying heterogeneity. Therefore, we examined microvascular and neurovascular inflammation pathology in NAWM and severe WMH three-dimensionally, along with gradual magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) signal (sub-)segmentation. In WMH, the vascular network exhibited reduced length and complexity compared to NAWM. Neuroinflammation was more severe in WMH. Vascular inflammation was more pronounced in NAWM, suggesting its potential significance in converting NAWM into WMH. Moreover, the (sub-)segmentation of FLAIR signal displayed varying degrees of vascular pathology, particularly within WMH regions. These findings highlight the intricate interplay between microvascular pathology and neuroinflammation in the transition from NAWM to WMH. Further examination of neurovascular inflammation across MRI-visible alterations could aid deepening our understanding on WMH conversion, and therewith how to improve the prognosis of SVD.
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Substância Branca , Humanos , Substância Branca/patologia , Doenças Neuroinflamatórias , Imageamento por Ressonância Magnética/métodos , Inflamação/diagnóstico por imagem , Inflamação/patologia , Fatores de RiscoRESUMO
The major vascular cause of dementia is cerebral small vessel disease (SVD). Its diagnosis relies on imaging hallmarks, such as white matter hyperintensities (WMH). WMH present a heterogenous pathology, including myelin and axonal loss. Yet, these might be only the "tip of the iceberg." Imaging modalities imply that microstructural alterations underlie still normal-appearing white matter (NAWM), preceding the conversion to WMH. Unfortunately, direct pathological characterization of these microstructural alterations affecting myelinated axonal fibers in WMH, and especially NAWM, is still missing. Given that there are no treatments to significantly reduce WMH progression, it is important to extend our knowledge on pathological processes that might already be occurring within NAWM. Staining of myelin with Luxol Fast Blue, while valuable, fails to assess subtle alterations in white matter microstructure. Therefore, we aimed to quantify myelin surrounding axonal fibers and axonal- and microstructural damage in detail by combining (immuno)histochemistry with polarized light imaging (PLI). To study the extent (of early) microstructural damage from periventricular NAWM to the center of WMH, we refined current analysis techniques by using deep learning to define smaller segments of white matter, capturing increasing fluid-attenuated inversion recovery signal. Integration of (immuno)histochemistry and PLI with post-mortem imaging of the brains of individuals with hypertension and normotensive controls enables voxel-wise assessment of the pathology throughout periventricular WMH and NAWM. Myelin loss, axonal integrity, and white matter microstructural damage are not limited to WMH but already occur within NAWM. Notably, we found that axonal damage is higher in individuals with hypertension, particularly in NAWM. These findings highlight the added value of advanced segmentation techniques to visualize subtle changes occurring already in NAWM preceding WMH. By using quantitative MRI and advanced diffusion MRI, future studies may elucidate these very early mechanisms leading to neurodegeneration, which ultimately contribute to the conversion of NAWM to WMH.
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Obesity is a multifactorial disease associated with low-grade inflammation. The gut is thought to be involved in obesity-related inflammation, as it is continuously exposed to antigens from food, microbiota and metabolites. However, the exact underlying mechanisms are still unknown. Therefore, we examined the relation between gut pathology, microbiota, its metabolites and cytokines in adults with severe obesity. Individuals eligible for bariatric surgery were included. Fecal and plasma samples were collected at surgery timepoint, to assess microbiota and metabolite composition. Jejunal biopsies were collected during surgery and stained for cytotoxic T cells, macrophages, mast cells and tight junction component zonula occludens-1. Based on these stainings, the cohort was divided into four groups: high versus low intestinal inflammation and high versus low intestinal integrity. We found no significant differences in microbiota diversity between groups, nor for individual bacterial species. No significant differences in metabolites were observed between the intestinal inflammatory groups. However, some metabolites and cytokines differed between the intestinal integrity groups. Higher plasma levels of interleukin-8 and tauro-chenodeoxycholic acid were found, whereas isovaleric acid and acetic acid were lower in the high intestinal integrity group. As the results were very subtle, we suggest that our cohort shows very early and minor intestinal pathology.
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The major vascular cause of dementia is cerebral small vessel disease (SVD), including white matter hyperintensities (WMH) amongst others. While the underlying pathology of SVD remains unclear, chronic hypertension and neuroinflammation are recognized as important risk factors for SVD and for the conversion of normal-appearing white matter (NAWM) to WMH. Unfortunately, most studies investigating the role of neuroinflammation in WMH relied on peripheral blood markers, e.g., markers for systemic or vascular inflammation, as a proxy for inflammation in the brain itself. However, it is unknown whether such markers accurately capture inflammatory changes within the cerebral white matter. Therefore, we aimed to comprehensively investigate the impact of hypertension on perivascular- and neuroinflammation in both WMH and NAWM. We conducted high field brain magnetic resonance imaging (MRI), followed by (immuno-)histopathological staining of neuroinflammatory markers on human post-mortem brains of elderly people with a history of hypertension (n = 17) and age-matched normotensive individuals (n = 5). MRI images were co-registered to (immuno-)histopathological data including stainings for microglia and astroglia to assess changes in MRI-based WMH at microscopic resolution. Perivascular inflammation was carefully assessed based on the severity of perivascular astrogliosis of the smallest vessels throughout white matter regions. Hypertension was associated with a larger inflammatory response in both WMH and NAWM. Notably, the presence of close-range perivascular inflammation was twice as common among those with hypertension than in controls both in WMH and NAWM, suggesting that neurovascular inflammation is critical in the etiology of WMH. Moreover, a higher degree of microglial activation was related to a higher burden of WMH. Our results indicate that neuro(vascular)inflammation at the level of the brain itself is involved in the etiology of WMH. Future therapeutic strategies focusing on multitarget interventions including antihypertensive treatment as well as neuroinflammation may ameliorate WMH progression.
Assuntos
Doenças de Pequenos Vasos Cerebrais , Hipertensão , Substância Branca , Humanos , Idoso , Substância Branca/patologia , Doenças Neuroinflamatórias , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Imageamento por Ressonância Magnética/métodos , Hipertensão/complicações , Hipertensão/patologia , Inflamação/patologia , Doenças de Pequenos Vasos Cerebrais/complicações , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Doenças de Pequenos Vasos Cerebrais/patologiaRESUMO
Exercise and dietary interventions are promising approaches to tackle obesity and its obesogenic effects on the brain. We investigated the impact of exercise and possible synergistic effects of exercise and branched-chain amino acids (BCAA) supplementation on the brain and behavior in high-fat-diet (HFD)-induced obese Ldlr-/-.Leiden mice. Baseline measurements were performed in chow-fed Ldlr-/-.Leiden mice to assess metabolic risk factors, cognition, and brain structure using magnetic resonance imaging. Thereafter, a subgroup was sacrificed, serving as a healthy reference. The remaining mice were fed an HFD and divided into three groups: (i) no exercise, (ii) exercise, or (iii) exercise and dietary BCAA. Mice were followed for 6 months and aforementioned tests were repeated. We found that exercise alone changed cerebral blood flow, attenuated white matter loss, and reduced neuroinflammation compared to non-exercising HFD-fed mice. Contrarily, no favorable effects of exercise on the brain were found in combination with BCAA, and neuroinflammation was increased. However, cognition was slightly improved in exercising mice on BCAA. Moreover, BCAA and exercise increased the percentage of epididymal white adipose tissue and muscle weight, decreased body weight and fasting insulin levels, improved the circadian rhythm, and transiently improved grip strength. In conclusion, BCAA should be supplemented with caution, although beneficial effects on metabolism, behavior, and cognition were observed.
Assuntos
Resistência à Insulina , Camundongos , Animais , Doenças Neuroinflamatórias , Obesidade/metabolismo , Aminoácidos de Cadeia Ramificada , Suplementos Nutricionais , Dieta Hiperlipídica/efeitos adversos , Encéfalo/metabolismoRESUMO
The centrally-projecting Edinger-Westphal nucleus (EWcp) hosts a large population of neurons expressing urocortin 1 (Ucn1) and about half of these neurons also express the leptin receptor (LepRb). Previously, we have shown that the peripheral adiposity hormone leptin signaling energy surfeit modulates EWcp neurons' activity. Here, we hypothesized that Ucn1/LepRb neurons in the EWcp would act as a crucial neuronal node in the brain-white adipose tissue (WAT) axis modulating efferent sympathetic outflow to the WAT. We showed that leptin bound to neurons of the EWcp stimulated STAT3 phosphorylation, and increased Ucn1-production in a time-dependent manner. Besides, retrograde transneuronal tract-tracing using pseudorabies virus (PRV) identified EWcp Ucn1 neurons connected to WAT. Interestingly, reducing EWcp Ucn1 contents by ablating EWcp LepRb-positive neurons with leptin-saporin, did not affect food intake and body weight gain, but substantially (+26%) increased WAT weight accompanied by a higher plasma leptin level and changed plasma lipid profile. We also found that ablation of EWcp Ucn1/LepRb neurons resulted in lower respiratory quotient and oxygen consumption one week after surgery, but was comparable to sham values after 3 and 5 weeks of surgery. Taken together, we report that EWcp/LepRb/Ucn1 neurons not only respond to leptin signaling but also control WAT size and fat metabolism without altering food intake. These data suggest the existence of a EWcp-WAT circuitry allowing an organism to recruit fuels without being able to eat in situations such as the fight-or-flight response.
Assuntos
Tecido Adiposo Branco/metabolismo , Núcleo de Edinger-Westphal/metabolismo , Leptina/metabolismo , Receptores para Leptina/metabolismo , Fator de Transcrição STAT3/metabolismo , Sistema Nervoso Simpático/metabolismo , Urocortinas/metabolismo , Animais , Herpesvirus Suídeo 1 , Masculino , RatosRESUMO
Exposure to antibiotic treatment has been associated with increased vulnerability to various psychiatric disorders. However, a research gap exists in understanding how adolescent antibiotic therapy affects behavior and cognition. Many antibiotics that target bacterial translation may also affect mitochondrial translation resulting in impaired mitochondrial function. The brain is one of the most metabolically active organs, and hence is the most vulnerable to impaired mitochondrial function. We hypothesized that exposure to antibiotics during early adolescence would directly affect brain mitochondrial function, and result in altered behavior and cognition. We administered amoxicillin, chloramphenicol, or gentamicin in the drinking water to young adolescent male wild-type mice. Next, we assayed mitochondrial oxidative phosphorylation complex activities in the cerebral cortex, performed behavioral screening and targeted mass spectrometry-based acylcarnitine profiling in the cerebral cortex. We found that mice exposed to chloramphenicol showed increased repetitive and compulsive-like behavior in the marble burying test, an accurate and sensitive assay of anxiety, concomitant with decreased mitochondrial complex IV activity. Our results suggest that only adolescent chloramphenicol exposure leads to impaired brain mitochondrial complex IV function, and could therefore be a candidate driver event for increased anxiety-like and repetitive, compulsive-like behaviors.
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Antibacterianos/efeitos adversos , Comportamento Animal/efeitos dos fármacos , Transtornos Mentais/etiologia , Mitocôndrias/efeitos dos fármacos , Fatores Etários , Animais , Antibacterianos/farmacologia , Biomarcadores , Peso Corporal , Modelos Animais de Doenças , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Metabolismo Energético/efeitos dos fármacos , Masculino , Transtornos Mentais/diagnóstico , Camundongos , Mitocôndrias/metabolismoRESUMO
Mitochondria play a critical role in bioenergetics, enabling stress adaptation, and therefore, are central in biological stress responses and stress-related complex psychopathologies. To investigate the effect of mitochondrial dysfunction on the stress response and the impact on various biological domains linked to the pathobiology of depression, a novel mouse model was created. These mice harbor a gene trap in the first intron of the Ndufs4 gene (Ndufs4GT/GT mice), encoding the NDUFS4 protein, a structural component of complex I (CI), the first enzyme of the mitochondrial electron transport chain. We performed a comprehensive behavioral screening with a broad range of behavioral, physiological, and endocrine markers, high-resolution ex vivo brain imaging, brain immunohistochemistry, and multi-platform targeted mass spectrometry-based metabolomics. Ndufs4GT/GT mice presented with a 25% reduction of CI activity in the hippocampus, resulting in a relatively mild phenotype of reduced body weight, increased physical activity, decreased neurogenesis and neuroinflammation compared to WT littermates. Brain metabolite profiling revealed characteristic biosignatures discriminating Ndufs4GT/GT from WT mice. Specifically, we observed a reversed TCA cycle flux and rewiring of amino acid metabolism in the prefrontal cortex. Next, exposing mice to chronic variable stress (a model for depression-like behavior), we found that Ndufs4GT/GT mice showed altered stress response and coping strategies with a robust stress-associated reprogramming of amino acid metabolism. Our data suggest that impaired mitochondrial CI function is a candidate driver for altered stress reactivity and stress-induced brain metabolic reprogramming. These changes result in unique phenomic and metabolomic signatures distinguishing groups based on their mitochondrial genotype.
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Complexo I de Transporte de Elétrons , Mitocôndrias , Animais , Encéfalo/metabolismo , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Estresse FisiológicoRESUMO
Stroke is one of the leading causes of adult disability worldwide. After ischemic stroke, damaged tissue surrounding the irreversibly damaged core of the infarct, the penumbra, is still salvageable and is therefore a target for acute therapeutic strategies. The Mediterranean diet (MD) has been shown to lower stroke risk. MD is characterized by increased intake of extra-virgin olive oil, of which hydroxytyrosol (HT) is the foremost phenolic component. This study investigates the effect of an HT-enriched diet directly after stroke on regaining motor and cognitive functioning, MRI parameters, neuroinflammation, and neurogenesis. Stroke mice on an HT diet showed increased strength in the forepaws, as well as improved short-term recognition memory probably due to improvement in functional connectivity (FC). Moreover, mice on an HT diet showed increased cerebral blood flow (CBF) and also heightened expression of brain derived neurotrophic factor (Bdnf), indicating a novel neurogenic potential of HT. This result was additionally accompanied by an enhanced transcription of the postsynaptic marker postsynaptic density protein 95 (Psd-95) and by a decreased ionized calcium-binding adapter molecule 1 (IBA-1) level indicative of lower neuroinflammation. These results suggest that an HT-enriched diet could serve as a beneficial therapeutic approach to attenuate ischemic stroke-associated damage.
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Isquemia Encefálica/tratamento farmacológico , Azeite de Oliva/química , Álcool Feniletílico/análogos & derivados , Acidente Vascular Cerebral/tratamento farmacológico , Ração Animal , Animais , Antioxidantes , Comportamento Animal , Peso Corporal , Cognição/efeitos dos fármacos , Ingestão de Alimentos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora , Força Muscular , Álcool Feniletílico/química , Álcool Feniletílico/uso terapêutico , Distribuição AleatóriaRESUMO
BACKGROUND: Reduced expression of the serotonin transporter (SERT) promotes anxiety and cocaine intake in both humans and rats. We tested the hypothesis that median raphe nucleus (MRN) and dorsal raphe nucleus (DRN) serotonergic projections differentially mediate these phenotypes. METHODS: We used virally mediated RNA interference to locally downregulate SERT expression and compared the results with those of constitutive SERT knockout. Rats were allowed either short access (ShA) (1 hour) or long access (LgA) (6 hours) to cocaine self-administration to model moderate versus compulsive-like cocaine taking. RESULTS: SERT knockdown in the MRN increased cocaine intake selectively under ShA conditions and, like ShA cocaine self-administration, reduced corticotropin-releasing factor (CRF) immunodensity in the paraventricular nucleus of the hypothalamus. In contrast, SERT knockdown in the DRN increased cocaine intake selectively under LgA conditions and, like LgA cocaine self-administration, reduced CRF immunodensity in the central nucleus of the amygdala. SERT knockdown in the MRN or DRN produced anxiety-like behavior, as did withdrawal from ShA or LgA cocaine self-administration. The phenotype of SERT knockout rats was a summation of the phenotypes generated by MRN- and DRN-specific SERT knockdown. CONCLUSIONS: Our results highlight a differential role of serotonergic projections arising from the MRN and DRN in the regulation of cocaine intake. We propose that a cocaine-induced shift from MRN-driven serotonergic control of CRF levels in the hypothalamus to DRN-driven serotonergic control of CRF levels in the amygdala may contribute to the transition from moderate to compulsive intake of cocaine.
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Anestésicos Locais/administração & dosagem , Cocaína/administração & dosagem , Comportamento Compulsivo/patologia , Núcleo Dorsal da Rafe/patologia , Núcleos da Rafe do Mesencéfalo/patologia , Neurônios Serotoninérgicos/efeitos dos fármacos , Tonsila do Cerebelo/metabolismo , Anestésicos Locais/metabolismo , Animais , Ansiedade/etiologia , Ansiedade/metabolismo , Cocaína/metabolismo , Hormônio Liberador da Corticotropina/metabolismo , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Locomoção/efeitos dos fármacos , Locomoção/genética , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Motivação/efeitos dos fármacos , Motivação/genética , Núcleo Hipotalâmico Paraventricular/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/farmacologia , Ratos , Ratos Wistar , Autoadministração , Neurônios Serotoninérgicos/fisiologia , Serotonina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Fatores de Tempo , Transdução GenéticaRESUMO
Apolipoprotein E4 (ApoE4), one of three common isoforms of ApoE, is a major risk factor for late-onset Alzheimer disease (AD). ApoE-deficient mice, as well as mice expressing human ApoE4, display impaired learning and memory functions and signs of neurodegeneration. Moreover, ApoE protects against high-fat (HF) diet induced neurodegeneration by its role in the maintenance of the integrity of the blood-brain barrier. The influence of a HF diet on the progression of AD-like cognitive and neuropathological changes was assessed in wild-type (WT), human ApoE4 and ApoE-knockout (ApoE-/-) mice to evaluate the modulatory role of ApoE in this process. From 12 months of age, female WT, ApoE4, and ApoE-/- mice were fed either a standard or a HF diet (19% butter, 0.5% cholate, 1.25% cholesterol) throughout life. At 15 months of age mice performed the Morris water maze, evaluating spatial learning and memory. ApoE-/- showed increased spatial learning compared to WT mice (p = 0.009). HF diet improved spatial learning in WT mice (p = 0.045), but did not affect ApoE4 and ApoE-/- mice. Immunohistochemical analyses of the hippocampus demonstrated increased neuroinflammation (CD68) in the cornu ammonis 1 (CA1) region in ApoE4 (p = 0.001) and in ApoE-/- (p = 0.032) mice on standard diet. HF diet tended to increase CD68 in the CA1 in WT mice (p = 0.052), while it decreased in ApoE4 (p = 0.009), but ApoE-/- remained unaffected. A trend towards increased neurogenesis (DCX) was found in both ApoE4 (p = 0.052) and ApoE-/- mice (p = 0.068). In conclusion, these data suggest that HF intake induces different effects in WT mice compared to ApoE4 and ApoE-/- with respect to markers for cognition and neurodegeneration. We propose that HF intake inhibits the compensatory mechanisms of neuroinflammation and neurogenesis in aged female ApoE4 and ApoE-/- mice.
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Apolipoproteína E4/deficiência , Encéfalo/patologia , Encéfalo/fisiopatologia , Cognição/fisiologia , Inflamação/patologia , Plasticidade Neuronal , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Apolipoproteína E4/metabolismo , Peso Corporal , Giro Denteado/metabolismo , Dieta Hiperlipídica , Proteína 4 Homóloga a Disks-Large , Proteínas do Domínio Duplacortina , Proteína Duplacortina , Feminino , Técnicas de Introdução de Genes , Transportador de Glucose Tipo 1/metabolismo , Guanilato Quinases/metabolismo , Humanos , Imuno-Histoquímica , Aprendizagem em Labirinto , Proteínas de Membrana/metabolismo , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Neuropeptídeos/metabolismo , Tamanho do ÓrgãoRESUMO
Ghrelin exists in two forms in circulation, acyl ghrelin and des-acyl ghrelin, both of which have distinct and fundamental roles in a variety of physiological functions. Despite this fact, a large proportion of papers simply measure and refer to plasma ghrelin without specifying the acylation status. It is therefore critical to assess and state the acylation status of plasma ghrelin in all studies. In this study we tested the effect of des-acyl ghrelin administration on the hypothalamic-pituitary-adrenal axis and on anxiety-like behavior of mice lacking endogenous ghrelin and in ghrelin-O-acyltransferase (GOAT) knockout (KO) mice that have no endogenous acyl ghrelin and high endogenous des-acyl ghrelin. Our results show des-acyl ghrelin produces an anxiogenic effect under nonstressed conditions, but this switches to an anxiolytic effect under stress. Des-acyl ghrelin influences plasma corticosterone under both nonstressed and stressed conditions, although c-fos activation in the paraventricular nucleus of the hypothalamus is not different. By contrast, GOAT KO are anxious under both nonstressed and stressed conditions, although this is not due to corticosterone release from the adrenals but rather from impaired feedback actions in the paraventricular nucleus of the hypothalamus, as assessed by c-fos activation. These results reveal des-acyl ghrelin treatment and GOAT deletion have differential effects on the hypothalamic-pituitary-adrenal axis and anxiety-like behavior, suggesting that anxiety-like behavior in GOAT KO mice is not due to high plasma des-acyl ghrelin.
Assuntos
Aciltransferases/metabolismo , Ansiedade/fisiopatologia , Grelina/fisiologia , Sistema Hipotálamo-Hipofisário/fisiologia , Sistema Hipófise-Suprarrenal/fisiologia , Acilação , Aciltransferases/genética , Animais , Ansiedade/psicologia , Feminino , Masculino , Proteínas de Membrana , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
Maternal intake of omega-3 polyunsaturated fatty acids (n-3 PUFA) is critical during perinatal development of the brain. Docosahexaenoic acid (DHA) is the most abundant n-3 PUFA in the brain and influences neuronal membrane function and neuroprotection. The present study aims to assess the effect of dietary n-3 PUFA availability during the gestational and postnatal period on cognition, brain metabolism and neurohistology in C57BL/6J mice. Female wild-type C57BL/6J mice at day 0 of gestation were randomly assigned to either an n-3 PUFA deficient diet (0.05% of total fatty acids) or an n-3 PUFA adequate diet (3.83% of total fatty acids) containing preformed DHA and its precursor α-linolenic acid. Male offspring remained on diet and performed cognitive tests during puberty and adulthood. In adulthood, animals underwent (31)P magnetic resonance spectroscopy to assess brain energy metabolites. Thereafter, biochemical and immunohistochemical analyses were performed assessing inflammation, neurogenesis and synaptic plasticity. Compared to the n-3 PUFA deficient group, pubertal n-3 PUFA adequate fed mice demonstrated increased motor coordination. Adult n-3 PUFA adequate fed mice exhibited increased exploratory behavior, sensorimotor integration and spatial memory, while neurogenesis in the hippocampus was decreased. Selected brain regions of n-3 PUFA adequate fed mice contained significantly lower levels of arachidonic acid and higher levels of DHA and dihomo-γ-linolenic acid. Our data suggest that dietary n-3 PUFA can modify neural maturation and enhance brain functioning in healthy C57BL/6J mice. This indicates that availability of n-3 PUFA in infant diet during early development may have a significant impact on brain development.
Assuntos
Cognição/efeitos dos fármacos , Ácidos Graxos Ômega-3/farmacologia , Hipocampo/efeitos dos fármacos , Destreza Motora/efeitos dos fármacos , Neurogênese/efeitos dos fármacos , Ácido 8,11,14-Eicosatrienoico/farmacologia , Animais , Ácido Araquidônico/farmacologia , Proteína 4 Homóloga a Disks-Large , Ácidos Docosa-Hexaenoicos/farmacologia , Feminino , Guanilato Quinases/genética , Guanilato Quinases/metabolismo , Hipocampo/metabolismo , Imuno-Histoquímica , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Sinaptofisina/genética , Sinaptofisina/metabolismo , Ácido alfa-Linolênico/farmacologiaRESUMO
The short allelic variant of the serotonin transporter (5-HTT) promoter-linked polymorphic region (5-HTTLPR) has been associated with the etiology of major depression by interaction with early life stress (ELS). A frequently observed endophenotype in depression is the abnormal regulation of levels of stress hormones such as glucocorticoids. It is hypothesized that altered central glucocorticoid influence on stress-related behavior and memory processes could underlie the depressogenic interaction of 5-HTTLPR and ELS. One possible mechanism could be the altered expression of the genes encoding the glucocorticoid and mineralocorticoid receptors (GR, MR) and their inhibitory regulator FK506-binding protein 51 (FKBP5) in stress-related forebrain areas. To test this notion, we exposed heterozygous (5-HTT(+/-)) and homozygous (5-HTT(-/-)) serotonin transporter knockout rats and their wildtype littermates (5-HTT(+/+)) to daily 3 h maternal separations from postnatal day 2 to 14. In the medial prefrontal cortex (mPFC) and hippocampus of the adult male offspring, we found that GR, MR, and FKBP5 mRNA levels were affected by ELS × 5-HTT genotype interaction. Specifically, 5-HTT(+/+) rats exposed to ELS showed decreased GR and FKBP5 mRNA in the dorsal and ventral mPFC, respectively. In contrast, 5-HTT(+/-) rats showed increased MR mRNA levels in the hippocampus and 5-HTT(-/-) rats showed increased FKBP5 mRNA in the ventral mPFC after ELS exposure. These findings indicate that 5-HTT genotype determines the specific adaptation of GR, MR, and FKBP5 expression in response to early life adversity. Therefore, altered extra-hypothalamic glucocorticoid signaling should be considered to play a role in the depressogenic interaction of ELS and 5-HTTLPR.
RESUMO
BACKGROUND: Ghrelin plays important roles in glucose metabolism, appetite, and body weight regulation, and recent evidence suggests ghrelin prevents excessive anxiety under conditions of chronic stress. METHODS: We used ghrelin knockout (ghr-/-) mice to examine the role of endogenous ghrelin in anxious behavior and hypothalamic-pituitary-adrenal axis (HPA) responses to acute stress. RESULTS: Ghr-/- mice are more anxious after acute restraint stress, compared with wild-type (WT) mice, with three independent behavioral tests. Acute restraint stress exacerbated neuronal activation in the hypothalamic paraventricular nucleus and medial nucleus of the amygdala in ghr-/- mice compared with WT, and exogenous ghrelin reversed this effect. Acute stress increased neuronal activation in the centrally projecting Edinger-Westphal nucleus in WT but not ghr-/- mice. Ghr-/- mice exhibited a lower corticosterone response after stress, suggesting dysfunctional glucocorticoid negative feedback in the absence of ghrelin. We found no differences in dexamethasone-induced Fos expression between ghr-/- and WT mice, suggesting central feedback was not impaired. Adrenocorticotropic hormone replacement elevated plasma corticosterone in ghr-/-, compared with WT mice, indicating increased adrenal sensitivity. The adrenocorticotropic hormone response to acute stress was significantly reduced in ghr-/- mice, compared with control subjects. Pro-opiomelanocortin anterior pituitary cells express significant growth hormone secretagogue receptor. CONCLUSIONS: Ghrelin reduces anxiety after acute stress by stimulating the HPA axis at the level of the anterior pituitary. A novel neuronal growth hormone secretagogue receptor circuit involving urocortin 1 neurons in the centrally projecting Edinger-Westphal nucleus promotes an appropriate stress response. Thus, ghrelin regulates acute stress and offers potential therapeutic efficacy in human mood and stress disorders.