Alteration of Copper Fluxes in Brain Aging: A Longitudinal Study in Rodent Using 64CuCl2-PET/CT

Mechanism of Cu entry into the brain: many unanswered questions

Brain tissue requires high amounts of copper (Cu) for its key physiological processes, such as energy production, neurotransmitter synthesis, maturation of neuropeptides, myelination, synaptic plasticity, and radical scavenging. The requirements for Cu in the brain vary depending on specific brain regions, cell types, organism age, and nutritional status. Cu imbalances cause or contribute to several life-threatening neurologic disorders including Menkes disease, Wilson disease, Alzheimer's disease, Parkinson's disease, and others. Despite the well-established role of Cu homeostasis in brain development and function, the mechanisms that govern Cu delivery to the brain are not well defined. This review summarizes available information on Cu transfer through the brain barriers and discusses issues that require further research.

Rodent model intervention for prevention and optimal management of sarcopenia: A systematic review on the beneficial effects of nutrients & non-nutrients and exercise to improve skeletal muscle health

Sarcopenia is a common musculoskeletal disorder characterized by degenerative processes and is strongly linked to an increased susceptibility to falls, fractures, physical limitations, and mortality. Several models have been used to explore therapeutic and preventative measures as well as to gain insight into the molecular mechanisms behind sarcopenia. With novel experimental methodologies emerging to design foods or novel versions of conventional foods, understanding the impact of nutrition on the prevention and management of sarcopenia has become important. This review provides a thorough assessment of the use of rodent models of sarcopenia for understanding the aging process, focusing the effects of nutrients, plant extracts, exercise, and combined interventions on skeletal muscle health. According to empirical research, nutraceuticals and functional foods have demonstrated potential benefits in enhancing physical performance. In preclinical investigations, the administration of herbal extracts and naturally occurring bioactive compounds yielded advantageous outcomes such as augmented muscle mass and strength generation. Furthermore, herbal treatments exhibited inhibitory effects on muscle atrophy and sarcopenia. A substantial body of information establishes a connection between diet and the muscle mass, strength, and functionality of older individuals. This suggests that nutrition has a major impact in both the prevention and treatment of sarcopenia.

Assessment of Water Quality Parameters in Lake Hayq, Northeastern Ethiopia

Lake Hayq is one of the highland lakes of Ethiopia that furnishes very important ecosystem services, fishing, tourism, transportation, drinking water, livestock watering, and irrigation. However, the lake ecosystem is being degraded by pollution, siltation, and excessive growth of macrophytes, buffer zone degradation, overfishing, and climate variability. Therefore, this study was conducted to assess the physicochemical, heavy metals, and biological water quality parameters of Lake Hayq. Physiochemical (pH, water temperature, conductivity, TDS, total alkalinity, dissolved oxygen, Ca2+, Mg2+, Na+, K+, NH4+, NH3, NO2 -, NO3 -, CO3 -, HCO3 -, SO4 2-, PO4 3-, SiO2, and total phosphorus), heavy metals (Pb, Fe, Zn, Cr, Cu2+, Mn2+, and Ni), and biological (BOD5 and total coliforms) water quality parameters were analyzed both in situ and ex situ. The physicochemical parameters were measured using portable water quality measuring multimeters, the heavy metal analysis was done using the Atomic Absorption Spectrometer, the BOD5 was measured using a BOD5 meter, and the total coliform analysis was done using the spread plate technique. The collected data were analyzed using multivariate, two-way ANOVA to see the mean difference among sampling sites and seasons through the application of SPSS 16. Most of the water quality parameters of Lake Hayq have met the WHO standards for recreation, aquatic life, and drinking water quality. However, some parameters, such as Pb, BOD5, and total coliforms, were above WHO water quality permissible limits. Therefore, ecohydrological (nature-based) waste treatment methods such as macrophyte restoration in buffer zones and ecofriendly farming activities should be practiced to minimize the contamination of the lake.

RNA analysis of diet-induced sarcopenic obesity in rats

Obesity has been suggested as a risk factor for sarcopenia. Sarcopenic obesity (SO), as a new category of obesity, is a high-risk geriatric syndrome in elderly individuals. However, knowledge about the molecular pathomechanisms of SO is still sparse. In the present study, starting at 13 months, male Sprague-Dawley (SD) rats were fed a high-fat diet (HFD) and normal diet (ND) for 28 weeks to establish a rodent animal model of SO with an identical protocol, which was further assessed and verified as a successful SO model. Through RNA-seq analysis of gastrocnemius muscle in SO rats, we found that differentially expressed genes (DEGs) and alternative splicing events (ASEs) focused mainly on inflammatory, immune-response, skeletal muscle cell differentiation, fat cell differentiation and antigen processing and presentation. Furthermore, as the core regulation factor of skeletal muscle, the mef2c (myocyte enhancer Factor 2C) gene also has a significant alternative 3' splice site (A3SS) and down-regulated expression in HFD-induced SO. The alternative genes targeted by mef2c identified by GO analysis were enriched in transcript regulation of RNA polymerase II promoter. In conclusion, these explorative findings in aging high-fat-fed rats might serve as a firm starting point for understanding the pathway and mechanism of sarcopenic obesity.

Non-invasive radionuclide imaging of trace metal trafficking in health and disease: "PET metallomics"

Several specific metallic elements must be present in the human body to maintain health and function. Maintaining the correct quantity (from trace to bulk) and location at the cell and tissue level is essential. The study of the biological role of metals has become known as metallomics. While quantities of metals in cells and tissues can be readily measured in biopsy and autopsy samples by destructive analytical techniques, their trafficking and its role in health and disease are poorly understood. Molecular imaging with radionuclides - positron emission tomography (PET) and single photon emission computed tomography (SPECT) - is emerging as a means to non-invasively study the acute trafficking of essential metals between organs, non-invasively and in real time, in health and disease. PET scanners are increasingly widely available in hospitals, and methods for producing radionuclides of some of the key essential metals are developing fast. This review summarises recent developments in radionuclide imaging technology that permit such investigations, describes the radiological and physicochemical properties of key radioisotopes of essential trace metals and useful analogues, and introduces current and potential future applications in preclinical and clinical investigations to study the biology of essential trace metals in health and disease.

Age-dependent decline of copper clearance at the blood-cerebrospinal fluid barrier

The homeostasis of copper (Cu) in the central nervous system is regulated by the blood-brain barrier and blood-cerebrospinal (CSF) barrier (BCB) in the choroid plexus. While proteins responsible for Cu uptake, release, storage and intracellular trafficking exist in the choroid plexus, the influence of age on Cu clearance from the CSF via the choroid plexus and how Cu transporting proteins contribute to the process are unelucidated. This study was designed to test the hypothesis that the aging process diminishes Cu clearance from the CSF of rats by disrupting Cu transporting proteins in the choroid plexus. Data from ventriculo-cisternal perfusion experiments demonstrated greater ⁶⁴Cu radioactivity in the CSF effluents of older rats (18 months) compared to younger (1 month) and adult (2 months) rats, suggesting much slower removal of Cu by the choroid plexus in old animals. Studies utilizing qPCR and immunofluorescence revealed an age-specific expression pattern of Cu transporting proteins in the choroid plexus. Moreover, proteomic analyses unraveled age-specific proteomes in the choroid plexus with distinct pathway differences, particularly associated with extracellular matrix and neurodevelopment between young and old animals. Taken together, these findings support an age-dependent deterioration in CSF Cu clearance, which appears to be associated with altered subcellular distribution of Cu transporting proteins and proteomes in the choroid plexus.

Rejuvenating the Aging Heart by Enhancing the Expression of the Cisd2 Prolongevity Gene

Aging is the major risk factor for cardiovascular disease, which is the leading cause of mortality worldwide among aging populations. Cisd2 is a prolongevity gene that mediates lifespan in mammals. Previously, our investigations revealed that a persistently high level of Cisd2 expression in mice is able to prevent age-associated cardiac dysfunction. This study was designed to apply a genetic approach that induces cardiac-specific Cisd2 overexpression (Cisd2 icOE) at a late-life stage, namely a time point immediately preceding the onset of old age, and evaluate the translational potential of this approach. Several discoveries are pinpointed. Firstly, Cisd2 is downregulated in the aging heart. This decrease in Cisd2 leads to cardiac dysfunction and impairs electromechanical performance. Intriguingly, Cisd2 icOE prevents an exacerbation of age-associated electromechanical dysfunction. Secondly, Cisd2 icOE ameliorates cardiac fibrosis and improves the integrity of the intercalated discs, thereby reversing various structural abnormalities. Finally, Cisd2 icOE reverses the transcriptomic profile of the aging heart, changing it from an older-age pattern to a younger pattern. Intriguingly, Cisd2 icOE modulates a number of aging-related pathways, namely the sirtuin signaling, autophagy, and senescence pathways, to bring about rejuvenation of the heart as it enters old age. Our findings highlight Cisd2 as a novel molecular target for developing therapies targeting cardiac aging.

Mouse models of sarcopenia: classification and evaluation

Sarcopenia is a progressive and widespread skeletal muscle disease that is related to an increased possibility of adverse consequences such as falls, fractures, physical disabilities and death, and its risk increases with age. With the deepening of the understanding of sarcopenia, the disease has become a major clinical disease of the elderly and a key challenge of healthy ageing. However, the exact molecular mechanism of this disease is still unclear, and the selection of treatment strategies and the evaluation of its effect are not the same. Most importantly, the early symptoms of this disease are not obvious and are easy to ignore. In addition, the clinical manifestations of each patient are not exactly the same, which makes it difficult to effectively study the progression of sarcopenia. Therefore, it is necessary to develop and use animal models to understand the pathophysiology of sarcopenia and develop therapeutic strategies. This paper reviews the mouse models that can be used in the study of sarcopenia, including ageing models, genetically engineered models, hindlimb suspension models, chemical induction models, denervation models, and immobilization models; analyses their advantages and disadvantages and application scope; and finally summarizes the evaluation of sarcopenia in mouse models.

Distribution and risk appraisal of dissolved trace elements in Begnas Lake and Rupa Lake, Gandaki Province, Nepal

Contamination of the trace elements (TEs) in the freshwater ecosystems is becoming a worldwide problem. This study was carried out to investigate the TEs contamination, and their associated health risk in Begnas Lake and Rupa Lake, Gandaki Province, Nepal. A total of 30 water samples were collected from both lakes during the pre-monsoon season in 2016. The samples were analyzed for the TEs including copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), cobalt (Co), chromium (Cr), cadmium (Cd), manganese (Mn), cesium (Cs), and arsenic (As) using inductively coupled plasma mass spectrometry. The results exhibited that the mean concentrations of all the TEs were higher in Rupa Lake as compared to Begnas Lake except Pb. Principal component analysis and cluster analysis revealed that both the geogenic and anthropic sources were the major contributors of TEs in the lake water. Anthropic activities were considered to contribute the TEs like Zn and Mn in lake water mainly via agricultural runoff, while evaluating the risk of TEs on human health all the elements showed HQ < 1 and CR < 10−4 indicating currently very low health risk concerns. In good agreement with above, the water quality index (WQI) of the Begnas Lake and Rupa Lake was 2.67 and 5.66, respectively, specifying the lake water was safe for drinking and public health concern. This appraisal would help the policymakers and concerned stakeholders for the sustainable management of Ramsar listed freshwater lakes in the Himalayas.

Cognitive Reserve in Model Systems for Mechanistic Discovery: The Importance of Longitudinal Studies

The goal of this review article is to provide a resource for longitudinal studies, using animal models, directed at understanding and modifying the relationship between cognition and brain structure and function throughout life. We propose that forthcoming longitudinal studies will build upon a wealth of knowledge gleaned from prior cross-sectional designs to identify early predictors of variability in cognitive function during aging, and characterize fundamental neurobiological mechanisms that underlie the vulnerability to, and the trajectory of, cognitive decline. Finally, we present examples of biological measures that may differentiate mechanisms of the cognitive reserve at the molecular, cellular, and network level.

The emerging value of 64Cu for molecular imaging and therapy

Along with other novel metallic radionuclides, copper-64 (⁶⁴Cu) is currently being investigated as an alternative option to the gallium-68 (⁶⁸Ga) and lutetium-177 (¹⁷⁷Lu) radiopharmaceuticals widely used for targeting somatostatin receptors, expressed by neuroendocrine tumors (NETs), and recently prostate specific membrane antigen (PSMA), expressed by prostate cancer cells. This interest is mostly driven by the peculiar nuclear properties of ⁶⁴Cu that make it an almost ideal example of theranostic radionuclide. In fact, ⁶⁴Cu emits both low-energy positrons, β^- particles and a swarm of Auger electrons. This combination of different emissions may allow to collect high-resolution PET images, but also to use the same radiopharmaceutical for eliciting a therapeutic effect. Another unique behavior of ⁶⁴Cu originates from the fundamental biological role played in organisms by the ionic forms of the copper element, which is naturally involved in a multitude of cellular processes including cell replication. These intrinsic biological characteristics has led to the discovery that ⁶⁴Cu, under its simplest dicationic form Cu²⁺, is able to specifically target a variety of cancerous cells and to detect the onset of a metastatic process in its initial stage. This short review reports an outline of the status of ⁶⁴Cu radiopharmaceuticals and of the most relevant results that are constantly disclosed by preclinical and investigational clinical studies.

General Aspects of Metal Ions as Signaling Agents in Health and Disease

This review focuses on the current knowledge on the involvement of metal ions in signaling processes within the cell, in both physiological and pathological conditions. The first section is devoted to the recent discoveries on magnesium and calcium-dependent signal transduction-the most recognized signaling agents among metals. The following sections then describe signaling pathways where zinc, copper, and iron play a key role. There are many systems in which changes in intra- and extra-cellular zinc and copper concentrations have been linked to important downstream events, especially in nervous signal transduction. Iron signaling is mostly related with its homeostasis. However, it is also involved in a recently discovered type of programmed cell death, ferroptosis. The important differences in metal ion signaling, and its disease-leading alterations, are also discussed.

Blood-Based Biomarkers for Predictive Diagnosis of Cognitive Impairment in a Pakistani Population

Numerous studies have identified an association between age-related cognitive impairment (CI) and oxidative damage, accumulation of metals, amyloid levels, tau, and deranged lipid profile. There is a concerted effort to establish the reliability of these blood-based biomarkers for predictive diagnosis of CI and its progression. We assessed the serum levels of high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, total cholesterol, selected metals (Cu, Al, Zn, Pb, Mn, Cad), and total-tau and amyloid beta-42 protein in mild (n = 71), moderate (n = 86) and severe (n = 25) cognitively impaired patients and compared them with age-matched healthy controls (n = 90) from Pakistan. We found that a decrease in HDL cholesterol (correlation coefficient r = 0.467) and amyloid beta-42 (r = 0.451) were associated with increased severity of CI. On the other hand, an increase in cholesterol ratio (r = -0.562), LDL cholesterol (r = -0.428), triglycerides, and total-tau (r = -0.443) were associated with increased severity of CI. Increases in cholesterol ratio showed the strongest association and correlated with increases in tau concentration (r = 0.368), and increased triglycerides were associated with decreased amyloid beta-42 (r = -0.345). Increased Cu levels showed the strongest association with tau increase and increased Zn and Pb levels showed the strongest association with reduced amyloid beta-42 levels. Receiver Operating Characteristic (ROC) showed the cutoff values of blood metals (Al, Pb, Cu, Cad, Zn, and Mn), total-tau, and amyloid beta-42 with sensitivity and specificity. Our data show for the first time that blood lipids, metals (particularly Cu, Zn, Pb, and Al), serum amyloid-beta-42/tau proteins modulate each other's levels and can be collectively used as a predictive marker for CI.

The 5,7-Dimethoxyflavone Suppresses Sarcopenia by Regulating Protein Turnover and Mitochondria Biogenesis-Related Pathways

Sarcopenia is a muscle disease featured by the loss of muscle mass and dysfunction with advancing age. The 5,7-dimethoxyflavone (DMF), a major flavone found in Kaempferia parviflora, has biological activities, including anti-diabetes, anti-obesity, and anti-inflammation. However, its anti-sarcopenic effect remains to be elucidated. This current study investigated the inhibitory activity of DMF on sarcopenia. Eighteen-month-old mice were orally administered DMF at the dose of 25 mg·kg⁻¹·day⁻¹ or 50 mg·kg⁻¹·day⁻¹ for 8 weeks. DMF not only stimulated grip strength and exercise endurance but also increased muscle mass and volume. Besides, DMF stimulated the phosphatidylinositol 3-kinase-Akt pathway, consequently activating the mammalian target of rapamycin-eukaryotic initiation factor 4E-binding protein 1-70-kDa ribosomal protein S6 kinase pathway for protein synthesis. DMF reduced the mRNA expression of E3 ubiquitin ligase- and autophagy-lysosomal-related genes involved in proteolysis via the phosphorylation of Forkhead box O3. DMF upregulated peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, nuclear respiratory factor 1, and mitochondrial transcription factor A along with the increase of relative mitochondrial DNA content. DMF alleviated inflammatory responses by reducing the tumor necrosis factor-alpha and interleukin-6 serum and mRNA levels. Collectively, DMF can be used as a natural agent to inhibit sarcopenia via improving protein turnover and mitochondria function.

Increased Vesicular Monoamine Transporter 2 (VMAT2) and Dopamine Transporter (DAT) Expression in Adolescent Brain Development: A Longitudinal Micro-PET/CT Study in Rodent

Background: Brain development and maturation in adolescence is a complex process with active changes of metabolic and neurotransmission pathways. Positron emission tomography (PET) is a useful imaging modality for tracking metabolic and functional changes in adolescent brain. In this study, changes of glucose metabolism, expression of vesicular monoamine transporter 2 and dopamine transporter during adolescent brain development in rats were investigated with PET/CT.

Methods: A longitudinal PET/CT study of age-dependent changes of VMAT2, DAT and glucose metabolism in adolescent brain was conducted in a group of Wistar rats (n = 6) post sequential intravenous injection of ¹⁸F-PF-(+)-DTBZ, ¹¹C-CFT, and ¹⁸F-FDG, respectively. PET acquisition was performed at 2, 4, 9, and 12 months of age. Radiotracer uptake in different brain regions, including the striatum, cerebellum, and hippocampus, were quantified and recorded as Standardized uptake value (SUV) and striatal specific uptake ratio (SUVR: SUV in brain regions/SUV in cerebellum).

Results: Variable uptake of ¹⁸F-PF-(+)-DTBZ and ¹¹C-CFT were detected, with highest level uptake in the striatum and accumbens. There was significant age-dependent increase of ¹⁸F-PF-(+)-DTBZ and ¹¹C-CFT uptake in the striatum from 2 months of age (SUV: 1.36 ± 0.22, 1.37 ± 0.39, respectively), to 4 months (SUV: 2.22 ± 0.29, 2.04 ± 0.33), 9 months (1.98 ± 0.34, 2.09 ± 0.18), 12 months (SUV: 1.93 ± 0.19, 2.00 ± 0.17) of age, SUV of ¹⁸F-FDG also increased from 2 months of age to older ages (SUV in the striatum: 3.71 ± 0.78 at 2 month, 5.28 ± 0.81, 5.14 ± 0.73, 4.94 ± 0.50 at 4, 9, 12 month, respectively).

Conclusion: Age-dependent increases of striatal of ¹⁸F-FDG, ¹⁸F-PF-(+)-DTBZ, and ¹¹C-CFT uptake were detected in rats from 2 to 4 month of age, demonstrating striatal development presents over the first 4 months of age. Four months of age can be considered a safe threshold to launch brain disease studies for exclusion of confusion of continuing tissue development. These findings support further investigation of age-dependent changes in expression of DAT, VMAT2, and glucose metabolism for their potential use as a new imaging biomarker for study of brain development and functional maturation.

Copper-64: a real theranostic agent

Ongoing studies of physiological and pathological processes have led to a corresponding need for new radiopharmaceuticals, especially when studies are limited by the absence of a particular radiolabeled target. Thus, the development of new radioactive tracers is highly relevant and can represent a significant contribution to efforts to elucidate important phenomena in biology. Currently, theranostics represents a new frontier in the fields of medicine and nuclear medicine, with the same compound being used for both diagnosis and treatment. In the human body, copper (Cu) is the third most abundant metal and it plays a crucial role in many biological functions. Correspondingly, in various acquired and inherited pathological conditions, such as cancer and Alzheimer’s disease, alterations in Cu levels have been found. Moreover, a wide spectrum of neurodegenerative disorders are associated with higher or lower levels of Cu, as well as inappropriately bound or distributed levels of Cu in the brain. In human cells, the membrane protein, hCtr1, binds Cu in its Cu(I) oxidation state in an energy-dependent manner. Copper-64 (⁶⁴Cu) is a cyclotron-produced radionuclide that has exhibited physical properties that are complementary for diagnosis and/or therapeutic purposes. To date, very few reports have described the clinical development of ⁶⁴Cu as a radiotracer for cancer imaging. In this review, we highlight recent insights in our understanding and use of ⁶⁴CuCl₂ as a theranostic agent for various types of tumors. To the best of our knowledge, no adverse effects or clinically observable pharmacological effects have been described for ⁶⁴CuCl₂ in the literature. Thus, ⁶⁴Cu represents a revolutionary radiopharmaceutical for positron emission tomography imaging and opens a new era in the theranostic field.

Insights into Trace Metal Metabolism in Health and Disease from PET: "PET Metallomics"

Essential trace metals such as copper, zinc, iron, and manganese perform critical functions in cellular and physiologic processes including catalytic, regulatory, and signaling roles. Disturbed metal homeostasis is associated with the pathogenesis of diseases such as dementia, cancer, and inherited metabolic abnormalities. Intracellular pathways involving essential metals have been extensively studied but whole-body fluxes and transport between different compartments remain poorly understood. The growing availability of PET scanners and positron-emitting isotopes of key essential metals, particularly 64Cu, 63Zn, and 52Mn, provide new tools with which to study these processes in vivo. This review highlights opportunities that now present themselves, exemplified by studies of copper metabolism that are in the vanguard of a new research front in molecular imaging: "PET metallomics."