Menkes disease and Wilson disease are debilitating neurometabolic disorders caused by mutations in the copper (Cu) transporters ATP7A and ATP7B, respectively. In either disease, normalization of systemic Cu levels often does not eliminate neurological deficits, suggesting dysregulated Cu homeostasis within vulnerable neuronal populations. However, the specific roles of ATP7A and ATP7B and the extent of their functional redundancy in neurons remain poorly defined. Here, we selectively deleted Atp7a or Atp7b in noradrenergic neurons, which express both transporters and require Cu for catecholamine biosynthesis. ATP7A deletion reduced Cu levels in the locus coeruleus, disrupted dopamine-β-hydroxylase localization, impaired norepinephrine synthesis, and induced proteomic signatures of defective vesicular trafficking and proteostasis, culminating in neurodegeneration and impaired regulation of energy balance and adaptive thermogenesis. In contrast, ATP7B deletion preserved Cu levels but altered intracellular Cu utilization, resulting in catecholamine imbalance, α-synuclein upregulation, aberrant dopamine-β-hydroxylase distribution, and dysregulated thermogenesis. These findings establish ATP7A and ATP7B as non-redundant regulators of noradrenergic function within neural circuits governing metabolic and energy homeostasis and provide a mechanistic framework for persistent neurological pathology independent of systemic Cu levels.

Inflammatory activity during multiple sclerosis (MS) often improves during pregnancy, suggesting that pregnancy-related immune adaptations affect the disease. Here we show that growth/differentiation factor-15 (GDF-15) increases during pregnancy and correlates with a reduced rate of MS relapses. GDF-15 also accumulates in the inflamed central nervous system, and its absence impairs inflammation resolution in a mouse model of MS. GDF-15 suppresses autoimmune T cell responses through an indirect signaling pathway involving the activation of GDNF family receptor α-like (GFRAL) on brainstem neurons. Therapeutic approaches, including neuronal gene delivery, recombinant GDF-15 administration and targeted chemogenetic activation of GFRAL-positive neurons induce β-adrenergic signaling and norepinephrine synthesis in the spleen, leading to decreased expression of integrins on T cells required for transmigration across the blood-brain barrier and confer protection against neuroinflammation in preclinical models of MS. These findings position GDF-15 as a crucial neuroimmune mediator and the GDF-15-GFRAL axis as promising target for MS.

The locus coeruleus is the primary site of norepinephrine (NE) synthesis in the brain. Its dysfunction has been implicated in the pathogenesis of Alzheimer's disease. Vascular risk factors, thyroid dysfunction, and vitamin deficiencies have also been associated with an increased risk of dementia. This study aimed to evaluate the relationship between the catecholaminergic system-by measuring cerebrospinal fluid (CSF) levels of L-3,4-dihydroxyphenylalanine (L-DOPA), dopamine (DA), and NE-and vascular risk factors, thyroid dysfunction, and vitamin deficiencies. We conducted a cross-sectional observational study in which CSF levels of L-DOPA, DA and NE were measured in 117 participants. Data on Blood Pressure (BP), heart rate, glycaemic and lipid profiles, smoking history, thyroid function and vitamin B12 and folic acid levels were collected for each participant. We found significant correlations between NE and CSF glucose levels (r = 0.308, p = 0.003) in participants without diabetes mellitus, between L-DOPA and orthostatic variation of diastolic BP (r = -0.288, p = 0.014) and high-density lipoprotein (r = 0.404, p = 0.001) and between NE and triglycerides (r = 0.271, p = 0.030) and folic acid (r = 0.298, p = 0.009). This is the first study to demonstrate correlations between CSF NE levels and CSF glucose, probably due to the effect of NE on astrocytes, and between CSF NE levels and folic acid, possibly related to its role in catecholamine synthesis. CSF L-DOPA levels were correlated with cardiovascular risk factors such as the orthostatic regulation of diastolic BP. These findings may contribute to a better understanding of the pathophysiology of neurodegenerative diseases.

Depression is a major global public health challenge, with current treatments often limited by suboptimal efficacy and adverse effects. This study investigated the antidepressant potential of cerebroprotein hydrolysate oral liquid (CHOL), a neuroprotective peptide-based solution derived from porcine brain through enzymatic hydrolysis. In model mice subjected to chronic social defeat stress (CSDS) and chronic restraint stress (CRS), CHOL was found to significantly attenuate depressive-like behaviors. Furthermore, CHOL also effectively reduced corticosterone-induced cell damage in PC12 cells. Metabolomic analysis revealed that depression modeling led to significant disturbances in neurotransmitter-related metabolites, especially norepinephrine, whereas CHOL could restore these metabolites in key brain regions and serum. Mechanism exploration revealed that the elevation of norepinephrine by CHOL was achieved through upregulation of tyrosine hydroxylase expression. Pharmacokinetic studies demonstrated that the 8 peptides in CHOL could rapidly distribute to the brain, with serine proteases, cysteine proteases, and metalloproteases identified as the key enzymes mediating CHOL metabolism. These findings underscored CHOL's preventive and therapeutic potential and provided mechanistic insights for its development as a novel antidepressant strategy. SIGNIFICANCE STATEMENT: This study integrated multiple depression models to confirm the significant antidepressant effects of cerebroprotein hydrolysate oral liquid. For the first time, we elucidated its underlying mechanism by regulating tyrosine hydroxylase expression and promoting norepinephrine synthesis. Furthermore, 8 brain-penetrant peptides were identified, and a targeted protease-inhibition strategy was developed to enhance in vivo exposure, thereby providing novel mechanistic insights and potential translational applications in depression therapeutics.

ABSTRACTBackgroundFibromyalgia is a chronic pain condition without an established aetiology. However, noradrenergic dysfunction is a possible mechanism to explain the constellation of symptoms associated with fibromyalgia. Noradrenaline synthesis in the locus coeruleus (LC) results in a paramagnetic by‐product, neuromelanin. Recently, a magnetic resonance imaging sequence sensitive to neuromelanin has been used to assay LC signal intensity, a proxy for noradrenergic system function. Here, we use MR imaging to investigate the noradrenergic‐locus coeruleus system in participants with fibromyalgia and healthy controls.MethodsForty‐six participants with fibromyalgia and 41 healthy controls were recruited for a cross‐sectional characterisation of LC signal intensity at 3 T, quantified from a 2D gradient echo acquisition. Participants completed the Revised Fibromyalgia Impact Questionnaire, as well as measures of anxiety, depression, sleep and the THINC‐it cognitive battery.ResultsAn independent groups t‐test revealed no differences in LC signal intensity between participants with fibromyalgia and healthy controls. For the participants with fibromyalgia, partial correlations accounting for age showed no association between LC signal intensity and fibromyalgia history, fibromyalgia symptom severity, anxiety, depression, insomnia or cognitive performance. Almost 90% of participants with fibromyalgia had been exposed to medications targeting noradrenergic function complicating the interpretation of these findings.ConclusionsLC signal intensity as measured by MR did not distinguish participants with fibromyalgia and healthy controls, nor was it associated with core fibromyalgia pain symptoms or associated symptoms. Dynamic measures of noradrenergic function may be required to understand noradrenergic contributions to fibromyalgia.Significance StatementThis study is the first report using MR measured signal intensity of the LC to examine noradrenergic function in participants with fibromyalgia. There was no difference in signal intensity when comparing patients to controls, nor did it associate with any symptoms or associated features of fibromyalgia. This suggests that lifetime noradrenergic function may not distinguish fibromyalgia.

Neutrophils play a crucial role in instigating inflammation as well as its resolution post-myocardial infarction (MI). Although granulopoiesis in the bone marrow (BM) is the major source of cardiac neutrophils post-MI, infiltration of neutrophils to the heart occurs much quicker than peak granulopoiesis. These observations suggest that sources other than granulopoiesis may supply neutrophils to the heart during the early hours post-MI. Using a combination of flow cytometry, BM ablation of hematopoietic stem cells, confocal microscopy and multiple proteomics analysis, we found that the first wave of neutrophils recruited to the ischemic heart is exclusively sourced from vasculature and not from granulopoiesis in the BM/ spleen. The MI-evoked neutrophilia during the early hours bore all hallmarks of demargination induced by classical demarginating agents such as dexamethasone/ norepinephrine (NE). Various pharmacological and genetic strategies aimed at suppressing NE synthesis or disruption of β-AR signaling reduced both neutrophil demargination as well as recruitment to the heart. Interestingly, however, despite a marked reduction in cardiac neutrophil burden only short-term inhibition of β-ARs improved cardiac remodeling and function. Our findings support a pharmacological strategy to contain the initial onslaught of neutrophils on the ischemic heart using β2-AR blockers to regulate the otherwise runaway inflammatory response.

PurposeDopaminergic dysregulation plays a critical role in myopia development in animal models. Although its relevance to human myopia remains uncertain, the observation that methylphenidate hydrochloride (MPH)—a dopamine (DA) and norepinephrine (NE) uptake inhibitor—slows myopia progression in children suggests a possible link. This study aimed to investigate whether MPH can inhibit myopic growth and elucidate the underlying mechanisms using an animal model.MethodsMPH was administered via oral, topical, or intravitreal routes for 7 days (minimum 5 per group) to chicks undergoing form-deprivation myopia (FDM). Myopia was assessed by refraction and axial length. Retinal DA and NE dynamics—including synthesis, release, uptake, breakdown (DA only), extracellular levels, and receptor sensitivity—were evaluated using mass spectrometry and chronoamperometry (minimum 5 per group). DA and NE receptors were pharmacologically blocked (DA = spiperone, SCH-23390; and NE = yohimbine) to determine their role in MPH's anti-myopic effects.ResultsMPH inhibited FDM via all administration routes (oral = 55%, P < 0.05, topical = 45%, P < 0.05, and intravitreal = 87%, P < 0.05 protection against myopic growth). It enhanced DA and NE synthesis while blocking their uptake, resulting in elevated extracellular levels. MPH's anti-myopic effects were abolished when DA or NE receptors were pharmacologically blocked. Additionally, NE receptor stimulation alone inhibited FDM (P < 0.05).ConclusionsMPH suppresses experimental myopia, with its effects linked to increased extracellular levels of DA and NE. These findings align with the anti-myopic effects observed in clinical studies, supporting a role for DA in human myopia and suggesting that NE may also contribute to the regulation of ocular growth.

Early life stress (ELS) profoundly impacts the brain and correlates with negative affective behaviors in adulthood. The locus coeruleus (LC), a stress-responsive brainstem nucleus that supplies most of the brain with norepinephrine (NE), is known to modulate negative affect. Using repeated maternal separation stress (MSS), we investigated the impact of ELS on the LC and stress-related behaviors in adulthood. We performed ex vivo cell-attached electrophysiology across the lifespan to reveal that MSS significantly increased LC firing during early development and adulthood but not in pre-adolescence and adolescence. We next examined potential changes in the expression of genes linked to LC function. In adulthood, MSS decreased mRNA levels for both the alpha-2A adrenergic receptor and dopamine beta-hydroxylase, the enzyme necessary for NE synthesis. At the behavioral level, MSS increased locomotion in approach-avoidance exploratory assays and increased immobility in the forced swim test. While forced swim increased LC cFos expression, a marker for neuronal excitation, in both No MSS and MSS mice, this increase was significantly lower in MSS mice than in No MSS controls. We further showed that MSS decreased the number of LC cells, possibly underlying the difference in cFos induction and gene expression between MSS and No MSS mice. Finally, we showed that inhibiting the LC in No MSS mice increased immobility time, but did not affect MSS immobility. Instead, LC inhibition in MSS mice increased climbing time. Together, this study demonstrates that MSS dysregulates LC-NE activity across the lifespan and disrupts LC regulation of coping strategies during stressful events.

Genome-wide association studies have revealed the involvement of 5'-nucleotidase domain-containing protein 2 (NT5DC2) in neuropsychiatric disorders such as schizophrenia and bipolar disorder; however, its function remains unclear. We recently found that NT5DC2 downregulation in PC12D cells increases catecholamine synthesis by promoting tyrosine hydroxylase (TH) activity. In addition, affinity purification-mass spectrometry suggested a potential interaction between NT5DC2 and monoamine oxidase A (MAO A). In this study, we examined the impact of NT5DC2 on MAO A activity in PC12D cells and the related effects on catecholamine metabolism. We analyzed changes in catecholamine metabolism in siRNA-mediated NT5DC2-downregulated PC12D cells by measuring the catecholamines and major acid metabolites produced by the addition of exogenous dopamine (DA) to PC12D cells, with DOPA synthesis suppressed by the addition of a TH inhibitor. Western blot analysis revealed that NT5DC2 primarily binds to the non-phosphorylated form of MAO A. NT5DC2 downregulation reduced MAO A activity, leading to decreased dopamine metabolism and increased noradrenaline synthesis. Our findings suggest that NT5DC2 regulates MAO A activity to control catecholamine synthesis. This study provides valuable insights into disorders associated with catecholamine dysregulation, such as Parkinson's disease and neuropsychiatric disorders.

Erzhi pill promotes norepinephrine synthesis in locus coeruleus through ERβ-TFAP2A-TH plays a neuroprotective role.

Degeneration of articular cartilage is the key underlying cause of most joint-related diseases and yet little is known about its regeneration. Here, we report that skeletal interoception induces anabolic synthesis of superficial membrane by tuning down sympathetic norepinephrine (NE). Specifically, the superficial membrane is consumed during animal activity and anabolically renewed by the underneath chondrocytes in the superficial zone (SFZ). Notably, by stereotactic knockdown of sympathetic NE synthesis in the paraventricular nucleus, articular cartilage thickness increases. Moreover, deletion of the gene encoding the prostaglandin E2 (PGE2) receptor, EP4, in sensory nerves for ascending interoceptive pathway induces damage of superficial membrane and articular cartilage degeneration. In contrast, increase of interoceptive signaling by elevation of local PGE2 reduces sympathetic outflow to promote the anabolic renewal of superficial membrane. Importantly, inducible knockout of the β-2-adrenergic-receptor (Adrb2) in the SFZ chondrocytes damages superficial membrane and treadmill running aggravates the damage. Mechanistically, NE-mediated activation of Adrb2 induces internalization of Adrb2 and TGF-β type II receptor as a complex, thereby regulating TGF-β activity for articular cartilage homeostasis regeneration. Together, physical activity induces an anabolic renewal of the superficial membrane by downregulation hypothalamic NE for optimized thicknessandintegrity of articular cartilage.

Osteocalcin (OCN) is an endocrine hormone that signals in the periphery, regulating male fertility, energy expenditure and glucose homeostasis. It can also cross the blood-brain-barrier and act on the brain via receptors GPR37 and GPR158. In the brain, OCN influences neurotransmitter synthesis of serotonin, norepinephrine, and dopamine. OCN’s function is related to cognitive and memory performance and lack of OCN is associated with anxiety and depression-like behavior in mice. We used multiparametric magnetic resonance imaging (MRI) including pharmacological MRI and resting state functional MRI, along with gene expression data for Gpr37 and Gpr158 to investigate the physiological effects of intravenously administered OCN on the wild type mouse brain. We found four core brain regions (brainstem, limbic output, association cortex, and basal ganglia) that are highly relevant in all three analytical modalities (i.e. pharmacological, resting state MRI and gene expression) and play therefore a major role in mediating OCN’s effect in the brain. This study provides the first imaging data of the physiological impact of OCN on the mouse brain, suggesting its potential role in modulating brain function and its relevance as a candidate for further investigation in anxiety, depression, and cognitive impairments.

Catheter-based pulmonary artery denervation (PADN) has achieved promising outcomes to treat pulmonary hypertension (PH). We herein present stereotactic body radiotherapy (SBRT) as a novel noninvasive approach for PADN. A single fraction of 15 Gy, 20 Gy or 25 Gy was delivered for PADN in a thromboxane A2 (TxA2) - induced acute PH swine model. We demonstrated that PADN by 20-Gy SBRT reduced mean pulmonary artery (PA) pressure during the TxA2 challenge. All SBRT dosages led to a deeper denervation area compared with radiofrequency ablation (RFA) and reduced sympathetic neural norepinephrine synthesis in the ablation zone. Probable radiation related side effects were mostly found in animals treated with 25-Gy. In subsequent monocrotaline-induced chronic PH animals, PADN by 20-Gy SBRT resulted in more significant improvement in pulmonary hemodynamics and PA remodeling in comparison to RFA. In summary, our findings suggest that appropriate SBRT scheme could balance the efficacy and safety for PADN, potentiating to be a novel strategy to treat PH.

The aim of this study was to investigate how ultraviolet B (UVB) light regulates AP-1 expression via the β2-adrenergic receptor (β2-AR) in epidermal keratinocytes, which in turn regulates melanin synthesis in melanocytes, thereby modulating downstream melanin production in skin hair follicles and altering mouse skin color. We established a UV-irradiated mouse model to investigate the effects of UV radiation on changes in skin color. By measuring changes in the expression of genes related to cutaneous sympathetic nerves, norepinephrine synthesis and melanin synthesis, we investigated the relationship between β2-AR expression and cutaneous melanogenesis and determined the localization of β2-AR in cells. The results of the siRNA-mediated transfection of keratinized cells with downregulated β2-AR expression were further verified in vitro. Our results suggest that UVB alters the color of the dorsal skin in mice by activating the AP-1/IL-6 pathway, which triggers the sympathetic release of norepinephrine, thereby increasing β2-AR expression in keratinocytes. Overall, our study improves the current understanding of how UVB light influences skin color changes and highlights the complex interplay between ultraviolet radiation and skin physiology.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10753-024-02221-0.

ABSTRACT Mephentermine is a cardiac stimulant similar to methamphetamine, a member of amphetamine. It increases noradrenaline release and acts on alpha and beta receptors. It leads to increased sympathomimetic action by increasing the release of noradrenaline from locus coeruleus, the principal norepinephrine synthesis sites, which is involved in the regulations of fight-and-flight response, agitation, sleep–wake cycle, and aggressive behaviors.

Tyrosine hydroxylase (TH) catalyzes hydroxylation of L-tyrosine to L-3,4-dihydroxyphenylalanine, the initial and rate-limiting step in the synthesis of dopamine, noradrenaline, and adrenaline. Mutations in the human TH gene are associated with hereditary motor disorders. The common C886T mutation identified in the mouse Th gene results in the R278H substitution in the enzyme molecule. We investigated the impact of this mutation on the TH activity in the mouse midbrain. The TH activity in the midbrain of Mus musculus castaneus (CAST) mice homozygous for the 886C allele was higher compared to C57BL/6 and DBA/2 mice homozygous for the 886T allele. Notably, this difference in the enzyme activity was not associated with changes in the Th gene mRNA levels and TH protein content. Analysis of the TH activity in the midbrain in mice from the F2 population obtained by crossbreeding of C57BL/6 and CAST mice revealed that the 886C allele is associated with a high TH activity. Moreover, this allele showed complete dominance over the 886T allele. However, the C886T mutation did not affect the levels of TH protein in the midbrain. These findings demonstrate that the C886T mutation is a major genetic factor determining the activity of TH in the midbrain of common laboratory mouse strains. Moreover, it represents the first common spontaneous mutation in the mouse Th gene whose influence on the enzyme activity has been demonstrated. These results will help to understand the role of TH in the development of adaptive and pathological behavior, elucidate molecular mechanisms regulating the activity of TH, and explore pharmacological agents for modulating its function.

The sympathetic nervous system drives hyperinflammatory responses to Clostridioides difficile infection

BackgroundMigraine and insomnia are prevalent conditions that often co-occur, each exacerbating the other and substantially impacting the quality of life. The locus coeruleus (LC), a brainstem region responsible for norepinephrine synthesis, participates in pain modulation, sleep/wake cycles, and emotional regulation, rendering it a potential nexus in the comorbidity of migraine and insomnia. Disruptions in the LC-noradrenergic system have been hypothesized to contribute to the comorbidities of migraine and insomnia, although neuroimaging evidence in humans remains scarce. In this study, we aimed to investigate the intrinsic functional connectivity (FC) network of the LC in patients with comorbid migraine and subjective chronic insomnia and patients with migraine with no insomnia (MnI) using resting-state functional magnetic resonance imaging (rs-fMRI) and seed-based FC analyses.MethodsIn this cross-sectional study, 30 patients with comorbid migraine and chronic insomnia (MI), 30 patients with MnI, and 30 healthy controls (HCs) were enrolled. Participants underwent neuropsychological testing and rs-fMRI. The LC-FC network was constructed using seed-based voxel-wise FC analysis. To identify group differences in LC-FC networks, voxel-wise covariance analysis was conducted with sex and age as covariates. Subsequently, a partial correlation analysis was conducted to probe the clinical relevance of aberrant LC-FC in patients with MI and MnI.ResultsExcept for the insomnia score, no other significant difference was detected in demographic characteristics and behavioral performance between the MI and MnI groups. Compared with HCs, patients with MI exhibited altered LC-FC in several brain regions, including the dorsomedial prefrontal cortex (DMPFC), anterior cerebellum, dorsolateral prefrontal cortex (DLPFC), thalamus, and parahippocampal gyrus (PHG). Lower FC between the LC and DLPFC was associated with greater insomnia severity, whereas higher FC between the LC and DMPFC was linked to longer migraine attack duration in the MI group.ConclusionOur findings reveal the presence of aberrant LC-FC networks in patients with MI, providing neuroimaging evidence of the interplay between these conditions. The identified LC-FC alterations may serve as potential targets for therapeutic interventions and highlight the importance of considering the LC-noradrenergic system in the management of MI.

Effects of acute inhibition of dopamine β-hydroxylase on neural responses to pups in adult virgin male California mice (Peromyscus californicus)

Tyrosine hydroxylase (TH) catalyzes hydroxylation of L-tyrosine to L-3,4-dihydroxyphenylalanine, the initial and rate-limiting step in the synthesis of dopamine, noradrenaline, and adrenaline. Mutations in the human TH gene are associated with hereditary motor disorders. The common C886T mutation identified in the mouse Th gene results in the R278H substitution in the enzyme molecule. We investigated the impact of this mutation on the TH activity in the mouse midbrain. The TH activity in the midbrain of Mus musculus castaneus (CAST) mice homozygous for the 886C allele was higher compared to C57BL/6 and DBA/2 mice homozygous for the 886T allele. Notably, this difference in the enzyme activity was not associated with changes in the Th gene mRNA levels and TH protein content. Analysis of the TH activity in the midbrain in mice from the F2 population obtained by crossbreeding of C57BL/6 and CAST mice revealed that the 886C allele is associated with a high TH activity. Moreover, this allele showed complete dominance over the 886T allele. However, the C886T mutation did not affect the levels of TH protein in the midbrain. These findings demonstrate that the C886T mutation is a major genetic factor determining the activity of TH in the midbrain of common laboratory mouse strains. Moreover, it represents the first common spontaneous mutation in the mouse Th gene whose influence on the enzyme activity has been demonstrated. These results will help to understand the role of TH in the development of adaptive and pathological behavior, elucidate molecular mechanisms regulating the activity of TH, and explore pharmacological agents for modulating its function.