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1.
J Pineal Res ; 76(4): e12961, 2024 May.
Article En | MEDLINE | ID: mdl-38751172

Melatonin is a neurohormone synthesized from dietary tryptophan in various organs, including the pineal gland and the retina. In the pineal gland, melatonin is produced at night under the control of the master clock located in the suprachiasmatic nuclei of the hypothalamus. Under physiological conditions, the pineal gland seems to constitute the unique source of circulating melatonin. Melatonin is involved in cellular metabolism in different ways. First, the circadian rhythm of melatonin helps the maintenance of proper internal timing, the disruption of which has deleterious effects on metabolic health. Second, melatonin modulates lipid metabolism, notably through diminished lipogenesis, and it has an antidiabetic effect, at least in several animal models. Third, pharmacological doses of melatonin have antioxidative, free radical-scavenging, and anti-inflammatory properties in various in vitro cellular models. As a result, melatonin can be considered both a circadian time-giver and a homeostatic monitor of cellular metabolism, via multiple mechanisms of action that are not all fully characterized. Aging, circadian disruption, and artificial light at night are conditions combining increased metabolic risks with diminished circulating levels of melatonin. Accordingly, melatonin supplementation could be of potential therapeutic value in the treatment or prevention of metabolic disorders. More clinical trials in controlled conditions are needed, notably taking greater account of circadian rhythmicity.


Circadian Rhythm , Homeostasis , Melatonin , Melatonin/metabolism , Animals , Humans , Circadian Rhythm/physiology , Homeostasis/physiology , Energy Metabolism/drug effects , Energy Metabolism/physiology , Pineal Gland/metabolism
2.
Physiol Res ; 73(2): 173-187, 2024 Apr 30.
Article En | MEDLINE | ID: mdl-38710052

Sodium is the main osmotically active ion in the extracellular fluid and its concentration goes hand in hand with fluid volume. Under physiological conditions, homeostasis of sodium and thus amount of fluid is regulated by neural and humoral interconnection of body tissues and organs. Both heart and kidneys are crucial in maintaining volume status. Proper kidney function is necessary to excrete regulated amount of water and solutes and adequate heart function is inevitable to sustain renal perfusion pressure, oxygen supply etc. As these organs are bidirectionally interconnected, injury of one leads to dysfunction of another. This condition is known as cardiorenal syndrome. It is divided into five subtypes regarding timeframe and pathophysiology of the onset. Hemodynamic effects include congestion, decreased cardiac output, but also production of natriuretic peptides. Renal congestion and hypoperfusion leads to kidney injury and maladaptive activation of renin-angiotensin-aldosterone system and sympathetic nervous system. In cardiorenal syndromes sodium and water excretion is impaired leading to volume overload and far-reaching negative consequences, including higher morbidity and mortality of these patients. Keywords: Cardiorenal syndrome, Renocardiac syndrome, Volume overload, Sodium retention.


Cardio-Renal Syndrome , Homeostasis , Sodium , Water-Electrolyte Balance , Humans , Cardio-Renal Syndrome/metabolism , Cardio-Renal Syndrome/physiopathology , Animals , Homeostasis/physiology , Water-Electrolyte Balance/physiology , Sodium/metabolism , Kidney/metabolism , Kidney/physiopathology , Water-Electrolyte Imbalance/metabolism , Water-Electrolyte Imbalance/physiopathology , Water/metabolism
3.
Chaos ; 34(5)2024 May 01.
Article En | MEDLINE | ID: mdl-38767461

Transient or partial synchronization can be used to do computations, although a fully synchronized network is sometimes related to the onset of epileptic seizures. Here, we propose a homeostatic mechanism that is capable of maintaining a neuronal network at the edge of a synchronization transition, thereby avoiding the harmful consequences of a fully synchronized network. We model neurons by maps since they are dynamically richer than integrate-and-fire models and more computationally efficient than conductance-based approaches. We first describe the synchronization phase transition of a dense network of neurons with different tonic spiking frequencies coupled by gap junctions. We show that at the transition critical point, inputs optimally reverberate through the network activity through transient synchronization. Then, we introduce a local homeostatic dynamic in the synaptic coupling and show that it produces a robust self-organization toward the edge of this phase transition. We discuss the potential biological consequences of this self-organization process, such as its relation to the Brain Criticality hypothesis, its input processing capacity, and how its malfunction could lead to pathological synchronization and the onset of seizure-like activity.


Homeostasis , Models, Neurological , Nerve Net , Neurons , Homeostasis/physiology , Neurons/physiology , Nerve Net/physiology , Humans , Action Potentials/physiology , Animals , Computer Simulation , Brain/physiology , Synaptic Transmission/physiology
4.
PeerJ ; 12: e17316, 2024.
Article En | MEDLINE | ID: mdl-38699185

This review discusses the importance of homeostasis with a particular emphasis on the acid-base (AB) balance, a crucial aspect of pH regulation in living systems. Two primary organ systems correct deviations from the standard pH balance: the respiratory system via gas exchange and the kidneys via proton/bicarbonate secretion and reabsorption. Focusing on kidney functions, we describe the complexity of renal architecture and its challenges for experimental research. We address specific roles of different nephron segments (the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule) in pH homeostasis, while explaining the physiological significance of ion exchange processes maintained by the kidneys, particularly the role of bicarbonate ions (HCO3-) as an essential buffer system of the body. The review will be of interest to researchers in the fields of physiology, biochemistry and molecular biology, which builds a strong foundation and critically evaluates existing studies. Our review helps identify the gaps of knowledge by thoroughly understanding the existing literature related to kidney acid-base homeostasis.


Acid-Base Equilibrium , Homeostasis , Kidney , Humans , Acid-Base Equilibrium/physiology , Kidney/metabolism , Kidney/physiology , Homeostasis/physiology , Hydrogen-Ion Concentration , Animals , Bicarbonates/metabolism
5.
J Coll Physicians Surg Pak ; 34(5): 617-619, 2024 May.
Article En | MEDLINE | ID: mdl-38720227

This cross-sectional study was aimed to compare insulin resistance, Triglyceride- Glucose (TyG) index, fatty liver index (FLI) and hepatic steatosis index (HSI), glycaemic and lipids among groups/quartiles based upon estimated Glucose Disposal Rate (eGDR) from August 2022 to December 2022 among 249 male participants. The eGDR results in (mg/kg/min) were divided into four quartiles as: Group-I: {<6.88, n = 62}, Group-II: {<6.88-9.45, n = 63}, Group-III: {9.46-10.39, n = 62}, and Group-IV: {>10.39, n = 62}. Fasting plasma glucose (FPG), HbA1c, low density lipoprotein (LDL), homeostasis model assessment for insulin-resistance (HOMAIR), and TyG index demonstrated significant worsening increase from high to low eGDR groups. Receiver operating curve (ROC) analysis to calculate area under curve (AUC) for diagnostic efficiency candidate indices for eGDR demonstrated highest AUC for FLI as AUC: 0.736 (95% CI: 0.669-0.803), p < 0.001, followed by FPG: AUC: 0.682 (95% CI: 0.606-0.757), HOMAIR: AUC: 0.670 (95% CI: 0.602-0.739), HSI: AUC: 0.660 (95% CI: 0.589-0.731), TyG index: 0.658 (95% CI: 0.583-0.732), and HbA1c: 0.639 (95% CI: 0.583-0.732). Glycaemic measures, lipid indices, insulin resistance and TyG index deteriorated with declining eGDR. Diagnostic performance as evaluated by AUC for eGDR was highest for FLI, followed by FPG, HOMAIR, HSI, TyG index, HbA1c, and triglycerides. Key Words: Triglyceride, Insulin, Glucose, Diabetes.


Blood Glucose , Homeostasis , Insulin Resistance , Triglycerides , Humans , Insulin Resistance/physiology , Male , Triglycerides/blood , Cross-Sectional Studies , Blood Glucose/metabolism , Homeostasis/physiology , Adult , Middle Aged , Fatty Liver/diagnosis , Fatty Liver/blood , Glycated Hemoglobin/metabolism , Glycated Hemoglobin/analysis
6.
CNS Neurosci Ther ; 30(5): e14748, 2024 05.
Article En | MEDLINE | ID: mdl-38727518

AIMS: To investigate the characteristics of dynamic cerebral autoregulation (dCA) after intravenous thrombolysis (IVT) and assess the relationship between dCA and prognosis. METHODS: Patients with unilateral acute ischemic stroke receiving IVT were prospectively enrolled; those who did not were selected as controls. All patients underwent dCA measurements, by quantifying the phase difference (PD) and gain, at 1-3 and 7-10 days after stroke onset. Simultaneously, two dCA-based nomogram models were established to verify the predictive value of dCA for patients with mild-to-moderate stroke. RESULTS: Finally, 202 patients who received IVT and 238 who did not were included. IVT was positively correlated with higher PD on days 1-3 and 7-10 after stroke onset. PD values in both sides at 1-3 days after stroke onset and in the affected side at 7-10 days after onset were independent predictors of unfavorable outcomes in patients who received IVT. Additionally, in patients with mild-to-moderate stroke who received IVT, the dCA-based nomogram models significantly improved the risk predictive ability for 3-month unfavorable outcomes. CONCLUSION: IVT has a positive effect on dCA in patients with acute stroke; furthermore, dCA may be useful to predict the prognosis of patients with IVT.


Homeostasis , Ischemic Stroke , Thrombolytic Therapy , Humans , Male , Female , Aged , Middle Aged , Prognosis , Thrombolytic Therapy/methods , Homeostasis/physiology , Homeostasis/drug effects , Ischemic Stroke/drug therapy , Ischemic Stroke/physiopathology , Fibrinolytic Agents/administration & dosage , Fibrinolytic Agents/therapeutic use , Cerebrovascular Circulation/physiology , Cerebrovascular Circulation/drug effects , Prospective Studies , Tissue Plasminogen Activator/administration & dosage , Tissue Plasminogen Activator/therapeutic use , Administration, Intravenous , Predictive Value of Tests , Aged, 80 and over , Nomograms , Stroke/drug therapy , Stroke/physiopathology
7.
J Physiol ; 602(11): 2627-2648, 2024 Jun.
Article En | MEDLINE | ID: mdl-38781025

Homeostasis constitutes a key concept in physiology and refers to self-regulating processes that maintain internal stability when adjusting to changing external conditions. It diminishes internal entropy constituting a driving force behind evolution. Natural selection might act on homeostatic regulatory mechanisms and control mechanisms including homeodynamics, allostasis, hormesis and homeorhesis, where different stable stationary states are reached. Regeneration is under homeostatic control through hormesis. Damage to tissues initiates a response to restore the impaired equilibrium caused by mild stress using cell proliferation, cell differentiation and cell death to recover structure and function. Repair is a homeorhetic change leading to a new stable stationary state with decreased functionality and fibrotic scarring without reconstruction of the 3-D pattern. Mechanisms determining entrance of the tissue or organ to regeneration or repair include the balance between innate and adaptive immune cells in relation to cell plasticity and stromal stem cell responses, and redox balance. The regenerative and reparative capacities vary in different species, distinct tissues and organs, and at different stages of development including ageing. Many cell signals and pathways play crucial roles determining regeneration or repair by regulating protein synthesis, cellular growth, inflammation, proliferation, autophagy, lysosomal function, metabolism and metalloproteinase cell signalling. Attempts to favour the entrance of damaged tissues to regeneration in those with low proliferative rates have been made; however, there are evolutionary constraint mechanisms leading to poor proliferation of stem cells in unfavourable environments or tumour development. More research is required to better understand the regulatory processes of these mechanisms.


Biological Evolution , Homeostasis , Regeneration , Homeostasis/physiology , Animals , Humans , Regeneration/physiology
8.
Comput Biol Med ; 176: 108540, 2024 Jun.
Article En | MEDLINE | ID: mdl-38728996

Colonic motility plays a vital role in maintaining proper digestive function. The rhythmic contractions and relaxations facilitate various types of motor functions that generate both propulsive and non-propulsive motility modes which in turn generate shear stresses on the epithelial surface. However, the interplay between colonic mucus, shear stress, and epithelium remains poorly characterized. Here, we present a colonic computational model that describes the potential roles of mucus and shear stress in both homeostasis and ulcerative colitis (UC). Our model integrates several key features, including the properties of the mucus bilayer and faeces, intraluminal pressure, and crypt characteristics to predict the time-space mosaic of shear stress. We show that the mucus thickness which could vary based on the severity of UC, may significantly reduce the amount of shear stress applied to the colonic crypts and effect faecal velocity. Our model also reveals an important spatial shear stress variance in homeostatic colonic crypts that suggests shear stress may have a modulatory role in epithelial cell migration, differentiation, apoptosis, and immune surveillance. Together, our study uncovers the rather neglected roles of mucus and shear stress in intestinal cellular processes during homeostasis and inflammation.


Colon , Gastrointestinal Motility , Homeostasis , Models, Biological , Mucus , Humans , Colon/physiology , Gastrointestinal Motility/physiology , Mucus/metabolism , Mucus/physiology , Homeostasis/physiology , Inflammation/metabolism , Inflammation/physiopathology , Computer Simulation , Stress, Mechanical , Colitis, Ulcerative/physiopathology , Colitis, Ulcerative/metabolism
9.
Hypertension ; 81(6): 1332-1344, 2024 Jun.
Article En | MEDLINE | ID: mdl-38629290

BACKGROUND: ANG (angiotensin II) elicits dipsogenic and pressor responses via activation of the canonical Gαq (G-protein component of the AT1R [angiotensin type 1 receptor])-mediated AT1R in the subfornical organ. Recently, we demonstrated that ARRB2 (ß-arrestin 2) global knockout mice exhibit a higher preference for salt and exacerbated pressor response to deoxycorticosterone acetate salt. However, whether ARRB2 within selective neuroanatomical nuclei alters physiological responses to ANG is unknown. Therefore, we hypothesized that ARRB2, specifically in the subfornical organ, counterbalances maladaptive dipsogenic and pressor responses to the canonical AT1R signaling. METHODS: Male and female Arrb2FLOX mice received intracerebroventricular injection of either adeno-associated virus (AAV)-Cre-GFP (green fluorescent protein) to induce brain-specific deletion of ARRB2 (Arrb2ICV-Cre). Arrb2FLOX mice receiving ICV-AAV-GFP were used as control (Arrb2ICV-Control). Infection with ICV-AAV-Cre primarily targeted the subfornical organ with few off targets. Fluid intake was evaluated using the 2-bottle choice paradigm with 1 bottle containing water and 1 containing 0.15 mol/L NaCl. RESULTS: Arrb2ICV-Cre mice exhibited a greater pressor response to acute ICV-ANG infusion. At baseline conditions, Arrb2ICV-Cre mice exhibited a significant increase in saline intake compared with controls, resulting in a saline preference. Furthermore, when mice were subjected to water-deprived or sodium-depleted conditions, which would naturally increase endogenous ANG levels, Arrb2ICV-Cre mice exhibited elevated saline intake. CONCLUSIONS: Overall, these data indicate that ARRB2 in selective cardiovascular nuclei in the brain, including the subfornical organ, counterbalances canonical AT1R responses to both exogenous and endogenous ANG. Stimulation of the AT1R/ARRB axis in the brain may represent a novel strategy to treat hypertension.


Blood Pressure , Homeostasis , Subfornical Organ , beta-Arrestin 2 , Animals , Subfornical Organ/metabolism , Mice , Blood Pressure/physiology , Blood Pressure/genetics , Male , Homeostasis/physiology , beta-Arrestin 2/metabolism , beta-Arrestin 2/genetics , Female , Mice, Knockout , Angiotensin II/pharmacology , Brain/metabolism , Receptor, Angiotensin, Type 1/genetics , Receptor, Angiotensin, Type 1/metabolism
10.
Acta Neurochir (Wien) ; 166(1): 190, 2024 Apr 24.
Article En | MEDLINE | ID: mdl-38653934

BACKGROUND: Cerebral perfusion pressure (CPP) management in the developing child with traumatic brain injury (TBI) is challenging. The pressure reactivity index (PRx) may serve as marker of cerebral pressure autoregulation (CPA) and optimal CPP (CPPopt) may be assessed by identifying the CPP level with best (lowest) PRx. To evaluate the potential of CPPopt guided management in children with severe TBI, cerebral microdialysis (CMD) monitoring levels of lactate and the lactate/pyruvate ratio (LPR) (indicators of ischemia) were related to actual CPP levels, autoregulatory state (PRx) and deviations from CPPopt (ΔCPPopt). METHODS: Retrospective study of 21 children ≤ 17 years with severe TBI who had both ICP and CMD monitoring were included. CPP, PRx, CPPopt and ΔCPPopt where calculated, dichotomized and compared with CMD lactate and lactate-pyruvate ratio. RESULTS: Median age was 16 years (range 8-17) and median Glasgow coma scale motor score 5 (range 2-5). Both lactate (p = 0.010) and LPR (p = < 0.001) were higher when CPP ≥ 70 mmHg than when CPP < 70. When PRx ≥ 0.1 both lactate and LPR were higher than when PRx < 0.1 (p = < 0.001). LPR was lower (p = 0.012) when CPPopt ≥ 70 mmHg than when CPPopt < 70, but there were no differences in lactate levels. When ΔCPPopt > 10 both lactate (p = 0.026) and LPR (p = 0.002) were higher than when ΔCPPopt < -10. CONCLUSIONS: Increased levels of CMD lactate and LPR in children with severe TBI appears to be related to disturbed CPA (PRx). Increased lactate and LPR also seems to be associated with actual CPP levels ≥ 70 mmHg. However, higher lactate and LPR values were also seen when actual CPP was above CPPopt. Higher CPP appears harmful when CPP is above the upper limit of pressure autoregulation. The findings indicate that CPPopt guided CPP management may have potential in pediatric TBI.


Brain Injuries, Traumatic , Cerebrovascular Circulation , Homeostasis , Intracranial Pressure , Lactic Acid , Humans , Brain Injuries, Traumatic/physiopathology , Brain Injuries, Traumatic/metabolism , Child , Adolescent , Homeostasis/physiology , Female , Male , Retrospective Studies , Intracranial Pressure/physiology , Cerebrovascular Circulation/physiology , Lactic Acid/metabolism , Lactic Acid/analysis , Microdialysis/methods , Pyruvic Acid/metabolism , Pyruvic Acid/analysis , Brain/metabolism , Brain/physiopathology
11.
Commun Biol ; 7(1): 404, 2024 Apr 03.
Article En | MEDLINE | ID: mdl-38570584

Mechanisms to modulate cerebrovascular tone are numerous, interconnected, and spatially dependent, increasing the complexity of experimental study design, interpretation of action-effect pathways, and mechanistic modelling. This difficulty is exacerbated when there is an incomplete understanding of these pathways. We propose interaction graphs to break down this complexity, while still maintaining a holistic view of mechanisms to modulate cerebrovascular tone. These graphs highlight the competing processes of neurovascular coupling, cerebral autoregulation, and cerebral reactivity. Subsequent analysis of these interaction graphs provides new insights and suggest potential directions for research on neurovascular coupling, modelling, and dementia.


Cerebrovascular Circulation , Neurovascular Coupling , Cerebrovascular Circulation/physiology , Homeostasis/physiology
12.
Nat Commun ; 15(1): 3377, 2024 Apr 20.
Article En | MEDLINE | ID: mdl-38643150

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.


Leptin , Pro-Opiomelanocortin , Mice , Animals , Leptin/metabolism , Phosphorylation , Pro-Opiomelanocortin/metabolism , Hypothalamus/metabolism , Homeostasis/physiology , Energy Metabolism/physiology , Neurons/metabolism
13.
Physiol Rep ; 12(9): e16027, 2024 May.
Article En | MEDLINE | ID: mdl-38684421

Resistance breathing may restore cardiac output (CO) and cerebral blood flow (CBF) during hypovolemia. We assessed CBF and cerebral autoregulation (CA) during tilt, resistance breathing, and paced breathing in 10 healthy subjects. Blood velocities in the internal carotid artery (ICA), middle cerebral arteries (MCA, four subjects), and aorta were measured by Doppler ultrasound in 30° and 60° semi-recumbent positions. ICA blood flow and CO were calculated. Arterial blood pressure (ABP, Finometer), and end-tidal CO2 (ETCO2) were recorded. ICA blood flow response was assessed by mixed-models regression analysis. The synchronization index (SI) for the variable pairs ABP-ICA blood velocity, ABP-MCA velocities in 0.005-0.08 Hz frequency interval was calculated as a measure of CA. Passive tilting from 30° to 60° resulted in 12% decrease in CO (p = 0.001); ICA blood flow tended to fall (p = 0.04); Resistance breathing restored CO and ICA blood flow despite a 10% ETCO2 drop. ETCO2 and CO contributed to ICA blood flow variance (adjusted R2: 0.9, p < 0.0001). The median SI was low (<0.2) indicating intact CA, confirmed by surrogate date testing. The peak SI was transiently elevated during resistance breathing in the 60° position. Resistance breathing may transiently reduce CA efficiency. Paced breathing did not restore CO or ICA blood flow.


Cerebrovascular Circulation , Homeostasis , Humans , Male , Cerebrovascular Circulation/physiology , Homeostasis/physiology , Pilot Projects , Adult , Female , Blood Flow Velocity/physiology , Middle Cerebral Artery/physiology , Middle Cerebral Artery/diagnostic imaging , Cardiac Output/physiology , Healthy Volunteers , Carotid Artery, Internal/physiology , Carotid Artery, Internal/diagnostic imaging , Blood Pressure/physiology
15.
Neurochem Int ; 176: 105725, 2024 Jun.
Article En | MEDLINE | ID: mdl-38561151

Epilepsy constitutes a global health concern, affecting millions of individuals and approximately one-third of patients exhibit drug resistance. Recent investigations have revealed alterations in cerebral iron content in both epilepsy patients and animal models. However, the extant literature lacks a comprehensive exploration into the ramifications of modulating iron homeostasis as an intervention in epilepsy. This study investigated the impact of deferasirox, a iron ion chelator, on epilepsy. This study unequivocally substantiated the antiepileptic efficacy of deferasirox in a kainic acid-induced epilepsy model. Furthermore, deferasirox administration mitigated seizure susceptibility in a pentylenetetrazol-induced kindling model. Conversely, the augmentation of iron levels through supplementation has emerged as a potential exacerbating factor in the precipitating onset of epilepsy. Intriguingly, our investigation revealed a hitherto unreported discovery: ITPRIP was identified as a pivotal modulator of excitatory synaptic transmission, regulating seizures in response to deferasirox treatment. In summary, our findings indicate that deferasirox exerts its antiepileptic effects through the precise targeting of ITPRIP and amelioration of cerebral iron homeostasis, suggesting that deferasirox is a promising and novel therapeutic avenue for interventions in epilepsy.


Anticonvulsants , Brain , Deferasirox , Epilepsy , Homeostasis , Iron Chelating Agents , Iron , Deferasirox/pharmacology , Iron/metabolism , Animals , Homeostasis/drug effects , Homeostasis/physiology , Epilepsy/drug therapy , Epilepsy/metabolism , Anticonvulsants/pharmacology , Anticonvulsants/therapeutic use , Male , Brain/drug effects , Brain/metabolism , Iron Chelating Agents/pharmacology , Iron Chelating Agents/therapeutic use , Mice , Kindling, Neurologic/drug effects , Pentylenetetrazole/toxicity , Rats, Sprague-Dawley
16.
J Dent Res ; 103(6): 642-651, 2024 Jun.
Article En | MEDLINE | ID: mdl-38665065

Alveolar bone, as tooth-supporting bone for mastication, is sensitive to occlusal force. However, the mechanism of alveolar bone loss after losing occlusal force remains unclear. Here, we performed single-cell RNA sequencing of nonhematopoietic (CD45-) cells in mouse alveolar bone after removing the occlusal force. Mesenchymal stromal cells (MSCs) and endothelial cell (EC) subsets were significantly decreased in frequency, as confirmed by immunofluorescence and flow cytometry. The osteogenic and proangiogenic abilities of MSCs were impaired, and the expression of mechanotransducers yes associated protein 1 (Yap) and WW domain containing transcription regulator 1 (Taz) in MSCs decreased. Conditional deletion of Yap and Taz from LepR+ cells, which are enriched in MSCs that are important for adult bone homeostasis, significantly decreased alveolar bone mass and resisted any further changes in bone mass induced by occlusal force changes. Interestingly, LepR-Cre; Yapf/f; Tazf/f mice showed a decrease in CD31hi endomucin (Emcn)hi endothelium, and the expression of some EC-derived signals acting on osteoblastic cells was inhibited in alveolar bone. Mechanistically, conditional deletion of Yap and Taz in LepR+ cells inhibited the secretion of pleiotrophin (Ptn), which impaired the proangiogenic capacity of LepR+ cells. Knockdown in MSC-derived Ptn repressed human umbilical vein EC tube formation in vitro. More important, administration of recombinant PTN locally recovered the frequency of CD31hiEmcnhi endothelium and rescued the low bone mass phenotype of LepR-Cre; Yapf/f; Tazf/f mice. Taken together, these findings suggest that occlusal force governs MSC-regulated endothelium to maintain alveolar bone homeostasis through the Yap/Taz/Ptn axis, providing a reference for further understanding of the relationship between dysfunction and bone homeostasis.


Bite Force , Homeostasis , Mesenchymal Stem Cells , YAP-Signaling Proteins , Animals , Mice , Homeostasis/physiology , Mesenchymal Stem Cells/physiology , Adaptor Proteins, Signal Transducing/metabolism , Endothelial Cells/physiology , Osteogenesis/physiology , Alveolar Bone Loss , X-Ray Microtomography , Flow Cytometry , Transcriptional Coactivator with PDZ-Binding Motif Proteins , Neovascularization, Physiologic/physiology
17.
Am J Physiol Renal Physiol ; 326(6): F877-F893, 2024 Jun 01.
Article En | MEDLINE | ID: mdl-38601984

Autophagy is a protective mechanism through which cells degrade and recycle proteins and organelles to maintain cellular homeostasis and integrity. An accumulating body of evidence underscores the significant impact of dysregulated autophagy on podocyte injury in chronic kidney disease (CKD). In this review, we provide a comprehensive overview of the diverse types of autophagy and their regulation in cellular homeostasis, with a specific emphasis on podocytes. Furthermore, we discuss recent findings that focus on the functional role of different types of autophagy during podocyte injury in chronic kidney disease. The intricate interplay between different types of autophagy and podocyte health requires further research, which is critical for understanding the pathogenesis of CKD and developing targeted therapeutic interventions.


Autophagy , Podocytes , Renal Insufficiency, Chronic , Podocytes/pathology , Podocytes/metabolism , Autophagy/physiology , Humans , Renal Insufficiency, Chronic/pathology , Renal Insufficiency, Chronic/metabolism , Renal Insufficiency, Chronic/physiopathology , Animals , Signal Transduction , Homeostasis/physiology
18.
Neurobiol Dis ; 196: 106506, 2024 Jun 15.
Article En | MEDLINE | ID: mdl-38648865

Imbalances of iron and dopamine metabolism along with mitochondrial dysfunction have been linked to the pathogenesis of Parkinson's disease (PD). We have previously suggested a direct link between iron homeostasis and dopamine metabolism, as dopamine can increase cellular uptake of iron into macrophages thereby promoting oxidative stress responses. In this study, we investigated the interplay between iron, dopamine, and mitochondrial activity in neuroblastoma SH-SY5Y cells and human induced pluripotent stem cell (hiPSC)-derived dopaminergic neurons differentiated from a healthy control and a PD patient with a mutation in the α-synuclein (SNCA) gene. In SH-SY5Y cells, dopamine treatment resulted in increased expression of the transmembrane iron transporters transferrin receptor 1 (TFR1), ferroportin (FPN), and mitoferrin2 (MFRN2) and intracellular iron accumulation, suggesting that dopamine may promote iron uptake. Furthermore, dopamine supplementation led to reduced mitochondrial fitness including decreased mitochondrial respiration, increased cytochrome c control efficiency, reduced mtDNA copy number and citrate synthase activity, increased oxidative stress and impaired aconitase activity. In dopaminergic neurons derived from a healthy control individual, dopamine showed comparable effects as observed in SH-SY5Y cells. The hiPSC-derived PD neurons harboring an endogenous SNCA mutation demonstrated altered mitochondrial iron homeostasis, reduced mitochondrial capacity along with increased oxidative stress and alterations of tricarboxylic acid cycle linked metabolic pathways compared with control neurons. Importantly, dopamine treatment of PD neurons promoted a rescue effect by increasing mitochondrial respiration, activating antioxidant stress response, and normalizing altered metabolite levels linked to mitochondrial function. These observations provide evidence that dopamine affects iron homeostasis, intracellular stress responses and mitochondrial function in healthy cells, while dopamine supplementation can restore the disturbed regulatory network in PD cells.


Dopamine , Dopaminergic Neurons , Homeostasis , Iron , Mitochondria , Parkinson Disease , alpha-Synuclein , Humans , Iron/metabolism , Mitochondria/metabolism , Mitochondria/drug effects , Homeostasis/physiology , Homeostasis/drug effects , Parkinson Disease/metabolism , Dopamine/metabolism , Dopaminergic Neurons/metabolism , Dopaminergic Neurons/drug effects , alpha-Synuclein/metabolism , Induced Pluripotent Stem Cells/metabolism , Cell Line, Tumor , Oxidative Stress/physiology , Oxidative Stress/drug effects
19.
Ageing Res Rev ; 97: 102311, 2024 Jun.
Article En | MEDLINE | ID: mdl-38636559

Ovarian aging is marked by a reduction in the quantity and quality of ovarian follicles, leading to a decline in female fertility and ovarian endocrine function. While the biological characteristics of ovarian aging are well-established, the exact mechanisms underlying this process remain elusive. Recent studies underscore the vital role of trace elements (TEs) in maintaining ovarian function. Imbalances in TEs can lead to ovarian aging, characterized by reduced enzyme activity, hormonal imbalances, ovulatory disorders, and decreased fertility. A comprehensive understanding of the relationship between systemic and cellular TEs balance and ovarian aging is critical for developing treatments to delay aging and manage age-related conditions. This review consolidates current insights into TEs homeostasis and its impact on ovarian aging, assesses how altered TEs metabolism affects ovarian aging, and suggests future research directions to prolong ovarian reproductive life. These studies are expected to offer novel approaches for mitigating ovarian aging.


Aging , Homeostasis , Ovary , Trace Elements , Female , Humans , Homeostasis/physiology , Ovary/metabolism , Trace Elements/metabolism , Aging/metabolism , Aging/physiology , Animals , Reproduction/physiology
20.
Ageing Res Rev ; 97: 102310, 2024 Jun.
Article En | MEDLINE | ID: mdl-38636560

Maintaining order at the tissue level is crucial throughout the lifespan, as failure can lead to cancer and an accumulation of molecular and cellular disorders. Perhaps, the most consistent and pervasive result of these failures is aging, which is characterized by the progressive loss of function and decline in the ability to maintain anatomical homeostasis and reproduce. This leads to organ malfunction, diseases, and ultimately death. The traditional understanding of aging is that it is caused by the accumulation of molecular and cellular damage. In this article, we propose a complementary view of aging from the perspective of endogenous bioelectricity which has not yet been integrated into aging research. We propose a view of aging as a morphostasis defect, a loss of biophysical prepattern information, encoding anatomical setpoints used for dynamic tissue and organ homeostasis. We hypothesize that this is specifically driven by abrogation of the endogenous bioelectric signaling that normally harnesses individual cell behaviors toward the creation and upkeep of complex multicellular structures in vivo. Herein, we first describe bioelectricity as the physiological software of life, and then identify and discuss the links between bioelectricity and life extension strategies and age-related diseases. We develop a bridge between aging and regeneration via bioelectric signaling that suggests a research program for healthful longevity via morphoceuticals. Finally, we discuss the broader implications of the homologies between development, aging, cancer and regeneration and how morphoceuticals can be developed for aging.


Aging , Humans , Aging/physiology , Aging/pathology , Animals , Homeostasis/physiology , Longevity/physiology , Electrophysiological Phenomena/physiology
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