RESUMO
The central nervous system has been implicated in the age-induced reduction in adipose tissue lipolysis. However, the underlying mechanisms remain unclear. Here, we show the expression of SLC7A14 is reduced in proopiomelanocortin (POMC) neurons of aged mice. Overexpression of SLC7A14 in POMC neurons alleviates the aging-reduced lipolysis, whereas SLC7A14 deletion mimics the age-induced lipolysis impairment. Metabolomics analysis reveals that POMC SLC7A14 increased taurochenodeoxycholic acid (TCDCA) content, which mediates the SLC7A14 knockout- or age-induced WAT lipolysis impairment. Furthermore, SLC7A14-increased TCDCA content is dependent on intestinal apical sodium-dependent bile acid transporter (ASBT), which is regulated by intestinal sympathetic afferent nerves. Finally, SLC7A14 regulates the intestinal sympathetic afferent nerves by inhibiting mTORC1 signaling through inhibiting TSC1 phosphorylation. Collectively, our study suggests the function for central SLC7A14 and an upstream mechanism for the mTORC1 signaling pathway. Moreover, our data provides insights into the brain-gut-adipose tissue crosstalk in age-induced lipolysis impairment.
Assuntos
Tecido Adiposo Branco , Envelhecimento , Sistema y+ de Transporte de Aminoácidos , Hipotálamo , Lipólise , Animais , Masculino , Camundongos , Tecido Adiposo Branco/metabolismo , Envelhecimento/metabolismo , Sistema y+ de Transporte de Aminoácidos/metabolismo , Sistema y+ de Transporte de Aminoácidos/genética , Hipotálamo/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Transdução de Sinais , Simportadores/metabolismo , Simportadores/genéticaRESUMO
Endoplasmic reticulum (ER) homeostasis in the hypothalamus has been implicated in the pathogenesis of diet-induced obesity (DIO) and type 2 diabetes; however, the underlying molecular mechanism remain vague and debatable. Here we report that SEL1L-HRD1 protein complex of the highly conserved ER-associated protein degradation (ERAD) machinery in POMC-expressing neurons ameliorates diet-induced obesity and its associated complications, partly by regulating the turnover of the long isoform of Leptin receptors (LepRb). Loss of SEL1L in POMC-expressing neurons attenuates leptin signaling and predisposes mice to HFD-associated pathologies including fatty liver, glucose intolerance, insulin and leptin resistance. Mechanistically, nascent LepRb, both wildtype and disease-associated Cys604Ser variant, are misfolding prone and bona fide substrates of SEL1L-HRD1 ERAD. In the absence of SEL1L-HRD1 ERAD, LepRb are largely retained in the ER, in an ER stress-independent manner. This study uncovers an important role of SEL1L-HRD1 ERAD in the pathogenesis of central leptin resistance and leptin signaling.
Assuntos
Dieta Hiperlipídica , Degradação Associada com o Retículo Endoplasmático , Retículo Endoplasmático , Leptina , Neurônios , Obesidade , Pró-Opiomelanocortina , Receptores para Leptina , Transdução de Sinais , Ubiquitina-Proteína Ligases , Animais , Obesidade/metabolismo , Obesidade/genética , Obesidade/etiologia , Obesidade/patologia , Neurônios/metabolismo , Leptina/metabolismo , Receptores para Leptina/metabolismo , Receptores para Leptina/genética , Camundongos , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , Dieta Hiperlipídica/efeitos adversos , Masculino , Retículo Endoplasmático/metabolismo , Hipotálamo/metabolismo , Estresse do Retículo Endoplasmático , Camundongos Endogâmicos C57BL , Proteínas/metabolismo , Proteínas/genética , Camundongos Knockout , Humanos , Peptídeos e Proteínas de Sinalização IntracelularRESUMO
The neuronal etiology of obesity is centered around a diet-induced inflammatory state in the arcuate nucleus of the hypothalamus, which impairs the functionality of pro-opiomelanocortine neurons (POMCs) responsible for whole-body energy homeostasis and feeding behavior. Intriguingly, systemic salt inducible kinase 2 (SIK2) knockout mice demonstrated reduced food intake and energy expenditure along with modestly dysregulated metabolic parameters, suggesting a causal link between the absence of SIK2 activity in POMCs and the observed phenotype. To test this hypothesis, we conducted a comparative secretomics study from POMC neurons following pharmacologically induced endoplasmic reticulum (ER) stress induction, a hallmark of metabolic inflammation and POMC dysregulation in diet-induced obese (DIO) mice. Our data provide significant in vitro evidence for the POMC-specific SIK2 activity in controlling energy metabolism and feeding in DIO mice by regulating the nature of the related POMC secretome. Our data also suggest that under physiological stress conditions, SIK2 may act as a gatekeeper for the secreted inflammatory factors and signaling molecules critical for cellular survival and energy homeostasis. On the other hand, in the absence of SIK2, the gate opens, leading to a surge of inflammatory cytokines and apoptotic cues concomitant with the dysregulation of POMC neurons.
Assuntos
Estresse do Retículo Endoplasmático , Homeostase , Pró-Opiomelanocortina , Proteínas Serina-Treonina Quinases , Animais , Pró-Opiomelanocortina/metabolismo , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Camundongos , Homeostase/efeitos dos fármacos , Camundongos Knockout , Neurônios/metabolismo , Neurônios/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Masculino , Obesidade/metabolismo , Obesidade/patologiaRESUMO
The coordination of food intake, energy storage, and expenditure involves complex interactions between hypothalamic neurons and peripheral tissues including pancreatic islets, adipocytes, muscle, and liver. Previous research shows that deficiency of the transcription factor Alx3 alters pancreatic islet-dependent glucose homeostasis. In this study we carried out a comprehensive assessment of metabolic alterations in Alx3 deficiency. We report that Alx3-deficient mice exhibit decreased food intake without changes in body weight, along with reduced energy expenditure and altered respiratory exchange ratio. Magnetic resonance imaging reveals increased adiposity and decreased muscle mass, which was associated with markers of motor and sympathetic denervation. By contrast, Alx3-deficient mice on a high-fat diet show attenuated weight gain and improved insulin sensitivity, compared to control mice. Gene expression analysis demonstrates altered lipogenic and lipolytic gene profiles. In wild type mice Alx3 is expressed in hypothalamic arcuate nucleus neurons, but not in major peripheral metabolic organs. Functional diffusion-weighted magnetic resonance imaging reveals selective hypothalamic responses to fasting in the arcuate nucleus of Alx3-deficient mice. Additionally, altered expression of proopiomelanocortin and melanocortin-3 receptor mRNA in the hypothalamus suggests impaired regulation of feeding behavior. This study highlights the crucial role for Alx3 in governing food intake, energy homeostasis, and metabolic nutrient partitioning, thereby influencing body mass composition.
Assuntos
Composição Corporal , Ingestão de Alimentos , Metabolismo Energético , Proteínas de Homeodomínio , Homeostase , Hipotálamo , Camundongos Knockout , Animais , Masculino , Camundongos , Núcleo Arqueado do Hipotálamo/metabolismo , Dieta Hiperlipídica , Ingestão de Alimentos/genética , Metabolismo Energético/genética , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Hipotálamo/metabolismo , Resistência à Insulina/genética , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genéticaRESUMO
Obesity poses a public health threat, reaching epidemic proportions. Our hypothesis suggests that some of this epidemic stems from its transmission across generations via paternal epigenetic mechanisms. To investigate this possibility, we focused on examining the paternal transmission of CpG methylation. First-generation male Wistar rats were fed either a high-fat diet (HF) or chow and were mated with females fed chow. We collected sperm from these males. The resulting offspring were raised on a chow diet until day 35, after which they underwent a dietary challenge. Diet-induced obese (DIO) male rats passed on the obesogenic trait to both male and female offspring. We observed significant hypermethylation of the Pomc promoter in the sperm of HF-treated males and in the hypothalamic arcuate nucleus (Arc) of their offspring at weaning. However, these differences in Arc methylation decreased later in life. This hypermethylation is correlated with increased expression of DNMT3B. Further investigating genes in the Arc that might be involved in obesogenic transgenerational transmission, using reduced representation bisulfite sequencing (RRBS) we identified 77 differentially methylated regions (DMRs), highlighting pathways associated with neuronal development. These findings support paternal CpG methylation as a mechanism for transmitting obesogenic traits across generations.
Assuntos
Peso Corporal , Metilação de DNA , Dieta Hiperlipídica , Obesidade , Ratos Wistar , Animais , Dieta Hiperlipídica/efeitos adversos , Masculino , Feminino , Ratos , Obesidade/genética , Obesidade/etiologia , Obesidade/metabolismo , Epigênese Genética , Ilhas de CpG , Regiões Promotoras Genéticas , Pró-Opiomelanocortina/genética , Pró-Opiomelanocortina/metabolismo , Núcleo Arqueado do Hipotálamo/metabolismo , Herança Paterna , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , DNA Metiltransferase 3B , Espermatozoides/metabolismoRESUMO
(1) Background: We examined the effect of the acute administration of olive oil (EVOO), linseed oil (GLO), soybean oil (SO), and palm oil (PO) on gastric motility and appetite in rats. (2) Methods: We assessed food intake, gastric retention (GR), and gene expression in all groups. (3) Results: Both EVOO and GLO were found to enhance the rate of stomach retention, leading to a decrease in hunger. On the other hand, the reduction in food intake caused by SO was accompanied by delayed effects on stomach retention. PO caused an alteration in the mRNA expression of NPY, POMC, and CART. Although PO increased stomach retention after 180 min, it did not affect food intake. It was subsequently verified that the absence of an autonomic reaction did not nullify the influence of EVOO in reducing food consumption. Moreover, in the absence of parasympathetic responses, animals that received PO exhibited a significant decrease in food consumption, probably mediated by lower NPY expression. (4) Conclusions: This study discovered that different oils induce various effects on parameters related to food consumption. Specifically, EVOO reduces food consumption primarily through its impact on the gastrointestinal tract, making it a recommended adjunct for weight loss. Conversely, the intake of PO limits food consumption in the absence of an autonomic reaction, but it is not advised due to its contribution to the development of cardiometabolic disorders.
Assuntos
Regulação do Apetite , Hipotálamo , Neuropeptídeo Y , Azeite de Oliva , Óleo de Palmeira , Óleo de Soja , Nervo Vago , Animais , Nervo Vago/efeitos dos fármacos , Nervo Vago/fisiologia , Hipotálamo/metabolismo , Hipotálamo/efeitos dos fármacos , Masculino , Azeite de Oliva/farmacologia , Neuropeptídeo Y/genética , Neuropeptídeo Y/metabolismo , Óleo de Palmeira/farmacologia , Regulação do Apetite/efeitos dos fármacos , Óleo de Soja/administração & dosagem , Óleo de Soja/farmacologia , Ratos Wistar , Óleo de Semente do Linho/farmacologia , Ratos , Ingestão de Alimentos/efeitos dos fármacos , Óleos de Plantas/farmacologia , Pró-Opiomelanocortina/genética , Pró-Opiomelanocortina/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Motilidade Gastrointestinal/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , RNA Mensageiro/metabolismo , RNA Mensageiro/genéticaRESUMO
OBJECTIVE: Proopiomelanocortin (POMC) neurons release potent anorexigenic neuropeptides, which suppress food intake and enhance energy expenditure via melanocortin receptors. Although the importance of central melanocortin in physiological regulation is well established, the underlying genetic mechanisms that define the functional identity of melanocortin neurons and maintain hypothalamic Pomc expression remain to be fully determined. In this study, we investigate the functional significance of Six3, a transcriptional regulator notably expressed in embryonic and adult mouse POMC neurons, in the regulation of hypothalamic Pomc expression and downstream physiological consequences. METHODS: We first evaluated the expression of Six3 in the developing and adult hypothalamus by double fluorescence in situ hybridization. Next, we assessed POMC immunoreactivity in mutant mice selectively lacking Six3 from Pomc-expressing neurons and quantified Pomc mRNA levels in a tamoxifen-inducible Six3 knockout mouse model activated at embryonic E9.5 days. We also determined glucose and insulin sensitivity, daily food intake, body composition and body weight in adult male and female mice lacking Six3 specifically from POMC neurons. Lastly, we assessed the physiological consequences of ablating Six3 from POMC neurons in adult mice. RESULTS: Six3 and Pomc were co-expressed in mouse hypothalamic neurons during development and adulthood. Mouse embryos deficient in Six3 showed reduced Pomc expression in the developing hypothalamus. Targeted deletion of Six3 specifically from POMC neurons resulted in decreased hypothalamic Pomc expression, increased daily food intake, enhanced glucose sensitivity and mild obesity in male but not in female mice. Finally, conditional removal of Six3 from POMC neurons in adult mice led to a reduction in hypothalamic POMC immunoreactivity with no significant effects in body weight or food intake. CONCLUSIONS: Altogether, our results demonstrate that Six3 plays an essential role in the early establishment of POMC neuron identity and the maintenance of physiological levels of hypothalamic Pomc expression. In addition, our study demonstrates that the functional significance of Six3 expression in POMC neurons is sexually dimorphic and age-dependent.
Assuntos
Proteínas de Homeodomínio , Hiperfagia , Hipotálamo , Camundongos Knockout , Neurônios , Obesidade , Pró-Opiomelanocortina , Animais , Feminino , Masculino , Camundongos , Ingestão de Alimentos , Metabolismo Energético , Proteínas de Homeodomínio/metabolismo , Proteínas de Homeodomínio/genética , Hiperfagia/metabolismo , Hipotálamo/metabolismo , Camundongos Endogâmicos C57BL , Proteínas do Tecido Nervoso/metabolismo , Proteínas do Tecido Nervoso/genética , Neurônios/metabolismo , Obesidade/metabolismo , Obesidade/genética , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genéticaRESUMO
Sestrin2 is a highly conserved protein that can be induced under various stress conditions. Researches have revealed that the signaling pathway of the mammalian target of rapamycin (mTOR) is essential in modulating both glucose and lipid metabolism. However, the precise involvement of Sestrin2 in the hypothalamus, particularly in pro-opiomelanocortin (POMC) neurons, in control of energy homeostasis remains uncertain. In this study, we aimed to investigate the functional role of Sestrin2 in hypothalamic POMC neurons in regulation of energy balance, as well as revealing the underlying mechanisms. Therefore, cre-dependent AAV virus encoding or silencing Sestrin2 was injected into the hypothalamic ARC of pomc-cre transgenic mice. The results demonstrated that Sestrin2 overexpression in POMC neurons ameliorated high-fat diet (HFD)-induced obesity and increased energy expenditure. Conversely, Sestrin2 deficiency in POMC neurons predisposed mice to HFD induced obesity. Additionally, the thermogenesis of brown adipose tissue and lipolysis of inguinal white adipose tissue were both enhanced by the increased sympathetic nerve innervation in Sestrin2 overexpressed mice. Further exploration revealed that Sestrin2 overexpression inhibited the mTOR signaling pathway in hypothalamic POMC neurons, which may account for the alleviation of systematic metabolic disturbance induced by HFD in these mice. Collectively, our findings demonstrate that Sestrin2 in POMC neurons plays a pivotal role in maintaining energy balance in a context of HFD-induced obesity by inhibiting the mTOR pathway, providing new insights into how hypothalamic neurons respond to nutritional signals to protect against obesity-associated metabolic dysfunction.
Assuntos
Dieta Hiperlipídica , Metabolismo Energético , Hipotálamo , Neurônios , Obesidade , Pró-Opiomelanocortina , Transdução de Sinais , Serina-Treonina Quinases TOR , Animais , Serina-Treonina Quinases TOR/metabolismo , Pró-Opiomelanocortina/metabolismo , Obesidade/metabolismo , Neurônios/metabolismo , Dieta Hiperlipídica/efeitos adversos , Hipotálamo/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Termogênese , Doenças Metabólicas/metabolismo , Doenças Metabólicas/etiologia , Camundongos Endogâmicos C57BL , Tecido Adiposo Marrom/metabolismo , SestrinasRESUMO
OBJECTIVE: During infection, metabolism and immunity react dynamically to promote survival through mechanisms that remain unclear. Pro-opiomelanocortin (POMC) cleavage products are produced and released in the brain and in the pituitary gland. One POMC cleavage product, alpha-melanocyte-stimulating hormone (α-MSH), is known to regulate food intake and energy expenditure and has anti-inflammatory effects. However, it is not known whether α-MSH is required to regulate physiological anti-inflammatory responses. We recently developed a novel mouse model with a targeted mutation in Pomc (Pomctm1/tm1 mice) to block production of all α-MSH forms which are required to regulate metabolism. To test whether endogenous α-MSH is required to regulate immune responses, we compared acute bacterial lipopolysaccharide (LPS)-induced inflammation between Pomctm1/tm1 and wild-type Pomcwt/wt mice. METHODS: We challenged 10- to 14-week-old male Pomctm1/tm1 and Pomcwt/wt mice with single i.p. injections of either saline or low-dose LPS (100 µg/kg) and monitored immune and metabolic responses. We used telemetry to measure core body temperature (Tb), ELISA to measure circulating cytokines, corticosterone and α-MSH, and metabolic chambers to measure body weight, food intake, activity, and respiration. We also developed a mass spectrometry method to measure three forms of α-MSH produced in the mouse hypothalamus and pituitary gland. RESULTS: LPS induced an exaggerated immune response in Pomctm1/tm1 compared to Pomcwt/wt mice. Both groups of mice were hypoactive and hypothermic following LPS administration, but Pomctm1/tm1 mice were significantly more hypothermic compared to control mice injected with LPS. Pomctm1/tm1 mice also had reduced oxygen consumption and impaired metabolic responses to LPS compared to controls. Pomctm1/tm1 mice had increased levels of key proinflammatory cytokines at 2 h and 4 h post LPS injection compared to Pomcwt/wt mice. Lastly, Pomcwt/wt mice injected with LPS compared to saline had increased total α-MSH in circulation 2 h post injection. CONCLUSIONS: Our data indicate endogenous α-MSH contributes to the inflammatory immune responses triggered by low-dose LPS administration and suggest that targeting the melanocortin system could be a potential therapeutic for the treatment of sepsis or inflammatory disease.
Assuntos
Inflamação , Lipopolissacarídeos , Pró-Opiomelanocortina , alfa-MSH , Animais , alfa-MSH/metabolismo , alfa-MSH/farmacologia , Lipopolissacarídeos/farmacologia , Camundongos , Masculino , Pró-Opiomelanocortina/metabolismo , Inflamação/metabolismo , Camundongos Endogâmicos C57BL , Corticosterona/metabolismo , Corticosterona/sangueRESUMO
Oxysterols are metabolites of cholesterol that regulate cholesterol homeostasis. Among these, the most abundant oxysterol is 27-hydroxycholesterol (27HC), which can cross the blood-brain barrier. Because 27HC functions as an endogenous selective estrogen receptor modulator, we hypothesize that 27HC binds to the estrogen receptor α (ERα) in the brain to regulate energy balance. Supporting this view, we found that delivering 27HC to the brain reduced food intake and activated proopiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (POMCARH) in an ERα-dependent manner. In addition, we observed that inhibiting brain ERα, deleting ERα in POMC neurons, or chemogenetic inhibition of POMCARH neurons blocked the anorexigenic effects of 27HC. Mechanistically, we further revealed that 27HC stimulates POMCARH neurons by inhibiting the small conductance of the calcium-activated potassium (SK) channel. Together, our findings suggest that 27HC, through its interaction with ERα and modulation of the SK channel, inhibits food intake as a negative feedback mechanism against a surge in circulating cholesterol.
Assuntos
Núcleo Arqueado do Hipotálamo , Receptor alfa de Estrogênio , Comportamento Alimentar , Hidroxicolesteróis , Neurônios , Pró-Opiomelanocortina , Núcleo Arqueado do Hipotálamo/metabolismo , Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Animais , Hidroxicolesteróis/farmacologia , Hidroxicolesteróis/metabolismo , Receptor alfa de Estrogênio/metabolismo , Neurônios/metabolismo , Neurônios/efeitos dos fármacos , Pró-Opiomelanocortina/metabolismo , Camundongos , FemininoRESUMO
Konjac glucomannan (KGM), high-viscosity dietary fiber, is utilized in weight management. Previous investigations on the appetite-suppressing effects of KGM have centered on intestinal responses to nutrients and gastric emptying rates, with less focus on downstream hypothalamic neurons of satiety hormones. In our studies, the molecular mechanisms through which KGM and its degradation products influence energy homeostasis via the adipocyte-hypothalamic axis have been examined. It was found that high-viscosity KGM more effectively stimulates enteroendocrine cells to release glucagon-like peptide-1 (GLP-1) and reduces ghrelin production, thereby activating hypothalamic neurons and moderating short-term satiety. Conversely, low-viscosity DKGM has been shown to exhibit stronger anti-inflammatory properties in the hypothalamus, enhancing hormone sensitivity and lowering the satiety threshold. Notably, both KGM and DKGM significantly reduced leptin signaling and fatty acid signaling in adipose tissue and activated brown adipose tissue thermogenesis to suppress pro-opiomelanocortin (POMC) expression and activate agouti-related protein (AgRP) expression, thereby reducing food intake and increasing energy expenditure. Additionally, high-viscosity KGM has been found to activate the adipocyte-hypothalamus axis more effectively than DKGM, thereby promoting greater daily energy expenditure. These findings provide novel insights into the adipocyte-hypothalamic axis for KGM to suppress appetite and reduce weight.
Assuntos
Adipócitos , Regulação do Apetite , Dieta Hiperlipídica , Metabolismo Energético , Hipotálamo , Camundongos Endogâmicos C57BL , Animais , Camundongos , Metabolismo Energético/efeitos dos fármacos , Hipotálamo/metabolismo , Hipotálamo/efeitos dos fármacos , Dieta Hiperlipídica/efeitos adversos , Masculino , Regulação do Apetite/efeitos dos fármacos , Adipócitos/metabolismo , Adipócitos/efeitos dos fármacos , Humanos , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Grelina/metabolismo , Leptina/metabolismo , Proteína Relacionada com Agouti/metabolismo , Proteína Relacionada com Agouti/genética , Termogênese/efeitos dos fármacos , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Obesidade/metabolismo , Obesidade/fisiopatologia , Obesidade/dietoterapia , MananasRESUMO
Repeated bouts of high-intensity interval training (HIIT) induce an improvement in metabolism via plasticity of melanocortin circuits and attenuated hypothalamic inflammation. HIF-1α, which plays a vital role in hypothalamus-mediated regulation of peripheral metabolism, is enhanced in the hypothalamus by HIIT. This study aimed to investigate the effects of HIIT on hypothalamic HIF-1α expression and peripheral metabolism in obese mice and the underlying molecular mechanisms. By using a high-fat diet (HFD)-induced obesity mouse model, we determined the effect of HIIT on energy balance and the expression of the hypothalamic appetite-regulating neuropeptides, POMC and NPY. Moreover, hypothalamic HIF-1α signaling and its downstream glycolytic enzymes were explored after HIIT intervention. The state of microglia and microglial NF-κB signaling in the hypothalamus were also examined in vivo. In vitro by using an adenovirus carrying shRNA-HIF1ß, we explored the impact of HIF-1 signaling on glycolysis and NF-κB inflammatory signaling in BV2 cells. Food intake was suppressed and whole-body metabolism was improved in exercised DIO mice, accompanied by changes in the expression of POMC and NPY. Moreover, total and microglial HIF-1α signaling were obviously attenuated in the hypothalamus, consistent with the decreased levels of glycolytic enzymes. Both HFD-induced microglial activation and hypothalamic NF-κB signaling were significantly suppressed following HIIT in vivo. In BV2 cells, after HIF-1 complex knockdown, glycolysis and NF-κB inflammatory signaling were significantly attenuated. The data indicate that HIIT improves peripheral metabolism probably via attenuated HFD-induced microglial activation and microglial NF-κB signaling in the hypothalamus, which could be mediated by suppressed microglial HIF-1α signaling.
Assuntos
Hipotálamo , Subunidade alfa do Fator 1 Induzível por Hipóxia , Inflamação , Camundongos Endogâmicos C57BL , Microglia , Transdução de Sinais , Animais , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Microglia/metabolismo , Masculino , Camundongos , Hipotálamo/metabolismo , Inflamação/metabolismo , Treinamento Intervalado de Alta Intensidade , Obesidade/metabolismo , Dieta Hiperlipídica/efeitos adversos , Condicionamento Físico Animal/fisiologia , NF-kappa B/metabolismo , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Neuropeptídeo Y/metabolismoRESUMO
Activation of prepronociceptin (PNOC)-expressing neurons in the arcuate nucleus (ARC) promotes high-fat-diet (HFD)-induced hyperphagia. In turn, PNOCARC neurons can inhibit the anorexic response of proopiomelanocortin (POMC) neurons. Here, we validate the necessity of PNOCARC activity for HFD-induced inhibition of POMC neurons in mice and find that PNOCARC-neuron-dependent inhibition of POMC neurons is mediated by gamma-aminobutyric acid (GABA) release. When monitoring individual PNOCARC neuron activity via Ca2+ imaging, we find a subpopulation of PNOCARC neurons that is inhibited upon gastrointestinal calorie sensing and disinhibited upon HFD feeding. Combining retrograde rabies tracing and circuit mapping, we find that PNOC neurons from the bed nucleus of the stria terminalis (PNOCBNST) provide inhibitory input to PNOCARC neurons, and this inhibitory input is blunted upon HFD feeding. This work sheds light on how an increase in caloric content of the diet can rewire a neuronal circuit, paving the way to overconsumption and obesity development.
Assuntos
Dieta Hiperlipídica , Hiperfagia , Núcleos Septais , Animais , Hiperfagia/metabolismo , Camundongos , Núcleos Septais/metabolismo , Neurônios/metabolismo , Masculino , Ácido gama-Aminobutírico/metabolismo , Pró-Opiomelanocortina/metabolismo , Neurônios GABAérgicos/metabolismo , Núcleo Arqueado do Hipotálamo/metabolismo , Camundongos Endogâmicos C57BL , Precursores de Proteínas , Receptores OpioidesRESUMO
The neuroendocrine marker genes Ptprn and Ptprn2 encode protein tyrosine phosphatase receptors N and N2, 2 members of protein tyrosine phosphatase receptors void of enzymatic activity, and whose function and mechanism of action have not been elucidated. To explore the role(s) of Ptprn and Ptprn2 on the hypothalamic-pituitary-adrenal axis, we used mice in which both genes were knocked out (DKO). The focus in this study was on corticotrophs and melanotrophs from the anterior and intermediate lobes of the pituitary gland, respectively. In both sexes, DKO caused an increase in the expression of the corticotroph/melanotroph genes Pomc and Tbx19 and the melanotroph-specific gene Pax7. We also found in vivo and in vitro increased synthesis and release of beta-endorphin, alpha-melanocyte-stimulating hormone, and ACTH in DKO mice, which was associated with increased serum corticosterone levels and adrenal mass. DKO also increased the expression of other melanotroph-specific genes, but not corticotroph-specific genes. The dopaminergic pathway in the hypothalamus and dopaminergic receptors in melanotrophs were not affected in DKO mice. However, hyperplasia of the intermediate lobe was observed in DKO females and males, accompanied by increased proopiomelanocortin immunoreactivity per cell. These results indicate that protein tyrosine phosphatase receptor type N contributes to hypothalamic-pituitary-adrenal function by being involved in processes governing postnatal melanotroph development and Pomc expression.
Assuntos
Melanotrofos , Camundongos Knockout , Hipófise , Pró-Opiomelanocortina , Animais , Camundongos , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Feminino , Masculino , Hipófise/metabolismo , Melanotrofos/metabolismo , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/genética , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/metabolismo , Sistema Hipófise-Suprarrenal/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Camundongos Endogâmicos C57BLRESUMO
PURPOSE: Corticotropin-releasing hormone (CRH) plays an important role in relief of pain by releasing analgesia-associated molecules in several inflammatory states. During inflammation, peripheral CRH acts on cells of the immune system to stimulate the local expression of proopiomelanocortin (POMC) and the production of ß-endorphin, which in turn binds to opioid receptors on sensory neurons to produce antinociception. In the present study, we further investigated the role of endogenous CRH in inflammatory pain by determining the effects of Crh-deficiency on this process. METHODS: For this purpose, we used Crh-deficient (Crh-/-) mice and their wildtype (Crh + / +) littermates in the CFA (Complete Freund's Adjuvant)-induced inflammatory pain model. Pain thresholds were evaluated with the Hargreaves apparatus. RESULTS: Our experiments showed that Crh deficiency led to increased pain response, which was associated with decreased POMC mRNA levels in locally inflamed paws of these mice. Furthermore, Crh-/- mice had higher paw edema than Crh + / + mice. Histological evaluation of inflamed paw tissues revealed increased inflammatory response in Crh-/- mice. Protein levels of proinflammatory cytokines, such as IL-6, TNF-α, and IL-1ß, were higher in inflamed tissue of Crh-/- mice compared to wildtype mice. Corticosterone replacement increased the pain threshold of Crh-/- mice, restored their paw volume to the levels of wildtype mice, and significantly reduced their proinflammatory cytokine levels. Furthermore, glucocorticoid administration significantly increased POMC mRNA expression in the inflamed paw. CONCLUSION: Our data suggest that genetic deficiency of CRH is associated with increased pain. This effect is likely attributable to the accompanying glucocorticoid insufficiency and is in part mediated by opioids expressed locally.
Assuntos
Hormônio Liberador da Corticotropina , Inflamação , Animais , Hormônio Liberador da Corticotropina/metabolismo , Inflamação/metabolismo , Camundongos , Adjuvante de Freund , Camundongos Knockout , Masculino , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Dor/metabolismo , Citocinas/metabolismo , Modelos Animais de DoençasRESUMO
Seipin is a key regulator of lipid metabolism, the deficiency of which leads to severe lipodystrophy. Hypothalamus is the pivotal center of brain that modulates appetite and energy homeostasis, where Seipin is abundantly expressed. Whether and how Seipin deficiency leads to systemic metabolic disorders via hypothalamus-involved energy metabolism dysregulation remains to be elucidated. In the present study, we demonstrated that Seipin-deficiency induced hypothalamic inflammation, reduction of anorexigenic pro-opiomelanocortin (POMC), and elevation of orexigenic agonist-related peptide (AgRP). Importantly, administration of rosiglitazone, a thiazolidinedione antidiabetic agent, rescued POMC and AgRP expression, suppressed hypothalamic inflammation, and restored energy homeostasis in Seipin knockout mice. Our findings offer crucial insights into the mechanism of Seipin deficiency-associated energy imbalance and indicates that rosiglitazone could serve as potential intervening agent towards metabolic disorders linked to Seipin.
Assuntos
Proteína Relacionada com Agouti , Metabolismo Energético , Subunidades gama da Proteína de Ligação ao GTP , Homeostase , Hipotálamo , Camundongos Knockout , Pró-Opiomelanocortina , Rosiglitazona , Animais , Camundongos , Hipotálamo/metabolismo , Metabolismo Energético/efeitos dos fármacos , Pró-Opiomelanocortina/genética , Pró-Opiomelanocortina/biossíntese , Proteína Relacionada com Agouti/genética , Subunidades gama da Proteína de Ligação ao GTP/genética , Rosiglitazona/farmacologia , Masculino , Doenças Neuroinflamatórias/etiologia , Camundongos Endogâmicos C57BL , Hipoglicemiantes/farmacologia , Hipoglicemiantes/uso terapêutico , Neuropeptídeos/genética , Neuropeptídeos/deficiência , Regulação da Expressão Gênica/efeitos dos fármacosRESUMO
The serotonin 2C receptor (5-HT2CR)-melanocortin pathway plays well-established roles in the regulation of feeding behavior and body weight homeostasis. Dysfunctions in this system, such as loss-of-function mutations in the Htr2c gene, can lead to hyperphagia and obesity. In this study, we aimed to investigate the potential therapeutic strategies for ameliorating hyperphagia, hyperglycemia, and obesity associated with a loss-of-function mutation in the Htr2c gene (Htr2cF327L/Y). We demonstrated that reexpressing functional 5-HT2CR solely in hypothalamic pro-opiomelanocortin (POMC) neurons is sufficient to reduce food intake and body weight in Htr2cF327L/Y mice subjected to a high-fat diet (HFD). In addition, 5-HT2CR expression restores the responsiveness of POMC neurons to lorcaserin, a selective agonist for 5-HT2CR. Similarly, administration of melanotan II, an agonist of the melanocortin receptor 4 (MC4R), effectively suppresses feeding and weight gain in Htr2cF327L/Y mice. Strikingly, promoting wheel-running activity in Htr2cF327L/Y mice results in a decrease in HFD consumption and improved glucose homeostasis. Together, our findings underscore the crucial role of the melanocortin system in alleviating hyperphagia and obesity related to dysfunctions of the 5-HT2CR, and further suggest that MC4R agonists and lifestyle interventions might hold promise in counteracting hyperphagia, hyperglycemia, and obesity in individuals carrying rare variants of the Htr2c gene.
Assuntos
Dieta Hiperlipídica , Hiperfagia , Obesidade , Pró-Opiomelanocortina , Receptor Tipo 4 de Melanocortina , Receptor 5-HT2C de Serotonina , Animais , Receptor 5-HT2C de Serotonina/metabolismo , Receptor 5-HT2C de Serotonina/genética , Masculino , Camundongos , Hiperfagia/metabolismo , Hiperfagia/genética , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Obesidade/metabolismo , Obesidade/genética , Receptor Tipo 4 de Melanocortina/genética , Receptor Tipo 4 de Melanocortina/metabolismo , Receptor Tipo 4 de Melanocortina/agonistas , alfa-MSH/farmacologia , alfa-MSH/análogos & derivados , Mutação com Perda de Função , Hipotálamo/metabolismo , Peso Corporal/efeitos dos fármacos , Ingestão de Alimentos/efeitos dos fármacos , Ingestão de Alimentos/fisiologia , Ingestão de Alimentos/genética , Neurônios/metabolismo , Neurônios/efeitos dos fármacos , Modelos Animais de Doenças , Hiperglicemia/metabolismo , Hiperglicemia/genética , Camundongos Endogâmicos C57BL , Benzazepinas , Peptídeos CíclicosRESUMO
Obesity is associated with hypogonadism in males, characterized by low testosterone and sperm number. Previous studies determined that these stem from dysregulation of hypothalamic circuitry that regulates reproduction, by unknown mechanisms. Herein, we used mice fed chronic high-fat diet, which mimics human obesity, to determine mechanisms of impairment at the level of the hypothalamus, in particular gonadotropin-releasing hormone (GnRH) neurons that regulate luteinizing hormone (LH), which then regulates testosterone. Consistent with obese humans, we demonstrated lower LH, and lower pulse frequency of LH secretion, but unchanged pituitary responsiveness to GnRH. LH pulse frequency is regulated by pulsatile GnRH secretion, which is controlled by kisspeptin. Peripheral and central kisspeptin injections, and DREADD-mediated activation of kisspeptin neurons, demonstrated that kisspeptin neurons were suppressed in obese mice. Thus, we investigated regulators of kisspeptin secretion. We determined that the LH response to NMDA was lower in obese mice, corresponding to fewer glutamate receptors in kisspeptin neurons, which may be critical for kisspeptin synchronization. Given that kisspeptin neurons also interact with anorexigenic POMC neurons, which are affected by obesity, we examined their cross talk, and determined that the LH response to either DREADD-mediated activation of POMC neurons or central injection of αMSH, a product of POMC, is abolished in obese mice. This was accompanied by diminished levels of αMSH receptor, MC4R, in kisspeptin neurons. Together, our studies determined that obesity leads to the downregulation of receptors that regulate kisspeptin neurons, which is associated with lower LH pulse frequency, leading to lower LH and hypogonadism.
Assuntos
Hormônio Liberador de Gonadotropina , Kisspeptinas , Hormônio Luteinizante , Camundongos Endogâmicos C57BL , Neurônios , Obesidade , Pró-Opiomelanocortina , Animais , Masculino , Kisspeptinas/metabolismo , Obesidade/metabolismo , Hormônio Luteinizante/metabolismo , Hormônio Luteinizante/sangue , Camundongos , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Hormônio Liberador de Gonadotropina/metabolismo , Dieta Hiperlipídica/efeitos adversosRESUMO
Zinc-alpha2-glycoprotein (AZGP1) has been implicated in peripheral metabolism; however, its role in regulating energy metabolism in the brain, particularly in POMC neurons, remains unknown. Here, we show that AZGP1 in POMC neurons plays a crucial role in controlling whole-body metabolism. POMC neuron-specific overexpression of Azgp1 under high-fat diet conditions reduces energy intake, raises energy expenditure, elevates peripheral tissue leptin and insulin sensitivity, alleviates liver steatosis, and promotes adipose tissue browning. Conversely, mice with inducible deletion of Azgp1 in POMC neurons exhibit the opposite metabolic phenotypes, showing increased susceptibility to diet-induced obesity. Notably, an increase in AZGP1 signaling in the hypothalamus elevates STAT3 phosphorylation and increases POMC neuron excitability. Mechanistically, AZGP1 enhances leptin-JAK2-STAT3 signaling by interacting with acylglycerol kinase (AGK) to block its ubiquitination degradation. Collectively, these results suggest that AZGP1 plays a crucial role in regulating energy homeostasis and glucose/lipid metabolism by acting on hypothalamic POMC neurons.
Assuntos
Leptina , Pró-Opiomelanocortina , Camundongos , Animais , Leptina/metabolismo , Fosforilação , Pró-Opiomelanocortina/metabolismo , Hipotálamo/metabolismo , Homeostase/fisiologia , Metabolismo Energético/fisiologia , Neurônios/metabolismoRESUMO
Nicotine use produces psychoactive effects, and chronic use is associated with physiological and psychological symptoms of addiction. However, chronic nicotine use is known to decrease food intake and body weight gain, suggesting that nicotine also affects central metabolic and appetite regulation. We recently showed that acute nicotine self-administration in nicotine-dependent animals produces a short-term increase in food intake, contrary to its long-term decrease of feeding behavior. As feeding behavior is regulated by complex neural signaling mechanisms, this study aimed to test the hypothesis that nicotine intake in animals exposed to chronic nicotine may increase activation of pro-feeding regions and decrease activation of pro-satiety regions to produce the acute increase in feeding behavior. FOS immunohistochemistry revealed that acute nicotine intake in nicotine self-administering animals increased activation of the pro-feeding arcuate and lateral hypothalamic nuclei and decreased activation of the pro-satiety parabrachial nucleus. Regional correlational analysis also showed that acute nicotine changes the functional connectivity of the hunger/satiety network. Further dissection of the role of the arcuate nucleus using electrophysiology found that putative POMC neurons in animals given chronic nicotine exhibited decreased firing following acute nicotine application. These brain-wide central signaling changes may contribute to the acute increase in feeding behavior we see in rats after acute nicotine and provide new areas of focus for studying both nicotine addiction and metabolic regulation.