Seventy years of pheochromocytomas and paragangliomas in Argentina. The FRENAR database

Pheochromocytomas and paragangliomas (PPGL) are neuroendocrine tumors characterized by the excessive production of catecholamines. This study aims to describe the clinical characteristics of PPGL cases in Argentina over recent decades. A multicenter retrospective cross-sectional analysis was carried out using a database comprising both pediatric and adult patients with confirmed PPGL diagnoses based on pathological reports. A cohort of 486 patients with PPGL was recruited. Women represent 58.4% of the patients, with a mean age of 38.3 years old at the time of diagnosis and 15.2% of the patients were under the age of 18. Hypertension, as well as classic signs and symptoms, were present in 80.9% of the patients. The adrenal incidentaloma, as a mode of presentation, increased in the last two decades rising from 3.9% (1953-2000) to 21.8% (2001-2022), p<0.001. Most tumors were located within the adrenal glands, accounting 83.0% of the cases, with bilateral occurrences noted in 20.0%. The median tumor size was 4.8cm. Local recurrence and metastases were observed in 10.9% and 12.2%. Out of 412 patients, 87.0% exhibited urinary excretion elevation of catecholamines and/or their metabolites. Furthermore, 148 patients, representing 30.4% of the study population, displayed a distinct genetic profile indicative of hereditary syndromes. The distribution of hereditary syndromes revealed that MEN2, VHL, and PGL4 constituted the most prevalent syndromes. This population-based study, spanning seven decades, offers valuable insights into the demographic and clinical characteristics of PPGL patients in Argentina.

The 3D in vitro Adrenoid cell model recapitulates the complexity of the adrenal gland

The crosstalk between the chromaffin and adrenocortical cells is essential for the endocrine activity of the adrenal glands. This interaction is also likely important for tumorigenesis and progression of adrenocortical cancer and pheochromocytoma. We developed a unique in vitro 3D model of the whole adrenal gland called Adrenoid consisting in adrenocortical carcinoma H295R and pheochromocytoma MTT cell lines. Adrenoids showed a round compact morphology with a growth rate significantly higher compared to MTT-spheroids. Confocal analysis of differential fluorescence staining of H295R and MTT cells demonstrated that H295R organized into small clusters inside Adrenoids dispersed in a core of MTT cells. Transmission electron microscopy confirmed the strict cell-cell interaction occurring between H295R and MTT cells in Adrenoids, which displayed ultrastructural features of more functional cells compared to the single cell type monolayer cultures. Adrenoid maintenance of the dual endocrine activity was demonstrated by the expression not only of cortical and chromaffin markers (steroidogenic factor 1, and chromogranin) but also by protein detection of the main enzymes involved in steroidogenesis (steroidogenic acute regulatory protein, and CYP11B1) and in catecholamine production (tyrosine hydroxylase and phenylethanolamine N-methyltransferase). Mass spectrometry detection of steroid hormones and liquid chromatography measurement of catecholamines confirmed Adrenoid functional activity. In conclusion, Adrenoids represent an innovative in vitro 3D-model that mimics the spatial and functional complexity of the adrenal gland, thus being a useful tool to investigate the crosstalk between the two endocrine components in the pathophysiology of this endocrine organ.

Biochemical Assessment of Pheochromocytoma and Paraganglioma

Pheochromocytoma and paraganglioma (PPGL) require prompt consideration and efficient diagnosis and treatment to minimize associated morbidity and mortality. Once considered, appropriate biochemical testing is key to diagnosis. Advances in understanding catecholamine metabolism have clarified why measurements of the O-methylated catecholamine metabolites rather than the catecholamines themselves are important for effective diagnosis. These metabolites, normetanephrine and metanephrine, produced respectively from norepinephrine and epinephrine, can be measured in plasma or urine, with choice according to available methods or presentation of patients. For patients with signs and symptoms of catecholamine excess, either test will invariably establish the diagnosis, whereas the plasma test provides higher sensitivity than urinary metanephrines for patients screened due to an incidentaloma or genetic predisposition, particularly for small tumors or in patients with an asymptomatic presentation. Additional measurements of plasma methoxytyramine can be important for some tumors, such as paragangliomas, and for surveillance of patients at risk of metastatic disease. Avoidance of false-positive test results is best achieved by plasma measurements with appropriate reference intervals and preanalytical precautions, including sampling blood in the fully supine position. Follow-up of positive results, including optimization of preanalytics for repeat tests or whether to proceed directly to anatomic imaging or confirmatory clonidine tests, depends on the test results, which can also suggest likely size, adrenal vs extra-adrenal location, underlying biology, or even metastatic involvement of a suspected tumor. Modern biochemical testing now makes diagnosis of PPGL relatively simple. Integration of artificial intelligence into the process should make it possible to fine-tune these advances.

A remarkable adaptive paradigm of heart performance and protection emerges in response to marked cardiac-specific overexpression of ADCY8

Adult (3 month) mice with cardiac-specific overexpression of adenylyl cyclase (AC) type VIII (TGAC8) adapt to an increased cAMP-induced cardiac workload (~30% increases in heart rate, ejection fraction and cardiac output) for up to a year without signs of heart failure or excessive mortality. Here, we show classical cardiac hypertrophy markers were absent in TGAC8, and that total left ventricular (LV) mass was not increased: a reduced LV cavity volume in TGAC8 was encased by thicker LV walls harboring an increased number of small cardiac myocytes, and a network of small interstitial proliferative non-cardiac myocytes compared to wild type (WT) littermates; Protein synthesis, proteosome activity, and autophagy were enhanced in TGAC8 vs WT, and Nrf-2, Hsp90α, and ACC2 protein levels were increased. Despite increased energy demands in vivo LV ATP and phosphocreatine levels in TGAC8 did not differ from WT. Unbiased omics analyses identified more than 2,000 transcripts and proteins, comprising a broad array of biological processes across multiple cellular compartments, which differed by genotype; compared to WT, in TGAC8 there was a shift from fatty acid oxidation to aerobic glycolysis in the context of increased utilization of the pentose phosphate shunt and nucleotide synthesis. Thus, marked overexpression of AC8 engages complex, coordinate adaptation "circuity" that has evolved in mammalian cells to defend against stress that threatens health or life (elements of which have already been shown to be central to cardiac ischemic pre-conditioning and exercise endurance cardiac conditioning) that may be of biological significance to allow for proper healing in disease states such as infarction or failure of the heart.

Clonidine suppression test for a reliable diagnosis of pheochromocytoma: When to use

OBJECTIVE

In clinical practice, false-positive results in biochemical testing for suspected pheochromocytoma/paraganglioma (PPGL) are not infrequent and may lead to unnecessary examinations. We aimed to evaluate the role of the clonidine suppression test (CST) in the era of analyses of plasma-free metanephrines for the diagnosis or exclusion of PPGL in patients with adrenal tumours and/or arterial hypertension.

DESIGN AND METHODS

This single-centre, prospective trial investigated the use of CST in 60 patients with suspected PPGL associated with out-patient elevations of plasma normetanephrine (NMN) and/or metanephrine (MN), in most cases accompanied with hypertension or an adrenal mass. Measurements of plasma catecholamines and free metanephrines were performed by liquid chromatography with electrochemical detection and tandem mass spectrometry, respectively.

RESULTS

Forty-six patients entered final analysis (n = 20 with PPGL and n = 26 with a nonfunctional adrenal mass and/or hypertension). CST reliably excluded false-positive baseline NMN results with a specificity of 100%. The sensitivity of CST improved from 85% to 94% when tumours with isolated MN increase (n = 3) were not considered. In patients with elevated baseline NMN (n = 24), CST correctly identified all patients without PPGL. Patients with falsely elevated baseline NMN results (n = 7, 26.9%) exhibited increases of baseline NMN up to 1.7-fold above the upper reference limit.

CONCLUSION

CST qualifies as a useful diagnostic tool for differential diagnosis of borderline elevated plasma-free NMN in patients with suspected PPGL. In this context, CST helps to correctly identify all false-positive NMN screening results.

Oscillatory waveform sharpness asymmetry changes in motor thalamus and motor cortex in a rat model of Parkinson's disease

Parkinson's disease (PD) causes bursty and oscillatory activity in basal ganglia output that is thought to contribute to movement deficits through impact on motor thalamus and motor cortex (MCx). We examined the effect of dopamine loss on motor thalamus and motor cortex activity by recording neuronal and LFP activities in ventroanterior-ventrolateral (VAVL) thalamus and MCx in urethane-anesthetised control and parkinsonian rats. Dopamine lesion decreased the firing rate and increased the bursting of putative pyramidal neurons in layer V, but not layer VI, of the MCx without changing other aspects of firing pattern. In contrast, dopamine lesion did not affect VAVL firing rate, pattern or low threshold calcium spike bursts. Slow-wave (~1 Hz) oscillations in LFP recordings were analyzed with conventional power and waveform shape analyses. While dopamine lesion did not influence total power, it was consistently associated with an increase in oscillatory waveform sharpness asymmetry (i.e., sharper troughs vs. peaks) in both motor thalamus and MCx. Furthermore, we found that measures of sharpness asymmetry were positively correlated in paired motor thalamus-MCx recordings, and that correlation coefficients were larger in dopamine lesioned rats. These data support the idea that dysfunctional MCx activity in parkinsonism emerges from subsets of cell groups (e.g. layer V pyramidal neurons) and is evident in the shape but not absolute power of slow-wave oscillations. Hypoactive layer V pyramidal neuron firing in dopamine lesioned rats is unlikely to be driven by VAVL thalamus and may, therefore, reflect the loss of mesocortical dopaminergic afferents and/or changes in intrinsic excitability.

Multiple catechols in human plasma after drinking caffeinated or decaffeinated coffee

BACKGROUND

Coffee is one of the most frequently consumed beverages worldwide. Research on effects of coffee drinking has focused on caffeine; however, coffee contains myriad biochemicals that are chemically unrelated to caffeine, including 3,4-dihydroxyphenyl compounds (catechols) such as caffeic acid and dihydrocaffeic acid (DHCA).

OBJECTIVE

This prospective within-subjects study examined effects of drinking caffeinated or decaffeinated coffee on plasma free (unconjugated) catechols measured by liquid chromatography with series electrochemical detection (LCED) after batch alumina extraction. To confirm coffee-related chromatographic peaks represented catechols, plasma was incubated with catechol-O-methyltransferase and S-adenosylmethionine before the alumina extraction; reductions in peak heights would identify catechols.

METHODS

Ten healthy volunteers drank 2 cups each of caffeinated and decaffeinated coffee on separate days after fasting overnight. With subjects supine, blood was drawn through an intravenous catheter up to 240 min after coffee ingestion and the plasma assayed by alumina extraction followed by LCED.

RESULTS

Within 15 min of drinking coffee of either type, >20 additional peaks were noted in chromatographs from the alumina eluates. Most of the coffee-related peaks corresponded to free catechols. Plasma levels of the catecholamines epinephrine and dopamine increased with both caffeinated and decaffeinated coffee. Levels of other endogenous catechols were unaffected. Plasma DHCA increased bi-phasically, in contrast with other coffee-related free catechols.

INTERPRETATION

Drinking coffee-whether caffeinated or decaffeinated-results in the rapid appearance of numerous free catechols in the plasma. These might affect the disposition of circulating catecholamines. The bi-phasic increase in plasma DHCA is consistent with production by gut bacteria.

Differential Susceptibilities of Catecholamines to Metabolism by Monoamine Oxidases

The endogenous catecholamines dopamine (DA), norepinephrine (NE), and epinephrine (EPI) play key roles in neurobehavioral, cardiovascular, and metabolic processes; various clinical disorders; and effects of numerous drugs. Steps in intracellular catecholamine synthesis and metabolism were delineated long ago, but there remains a knowledge gap. Catecholamines are metabolized by two isoforms of monoamine oxidase (MAO), MAO-A and MAO-B, and although the anatomic localization of MAO-A and MAO-B and substrate specificities of enzyme inhibitors are well characterized, relative susceptibilities of the endogenous catecholamines to enzymatic oxidation by MAO-A and MAO-B have not been studied systematically. MAOs catalyze the conversion of catecholamines to catecholaldehydes-3,4-dihydroxyphenylacetaldehyde (DOPAL) from DA and 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL) from NE and EPI. In this study we exploited the technical ability to assay DOPAL and DOPEGAL simultaneously with the substrate catecholamines to compare DA, NE, and EPI in their metabolism by MAO-A and MAO-B. For both MAO isoforms, DA was the better substrate compared to NE or EPI, which were metabolized equally. Since catecholaminergic neurons express mainly MAO-A, the finding that MAO-A is more efficient than MAO-B in metabolizing endogenous catecholamines reinforces the view that the predominant route of intraneuronal enzymatic oxidation of catecholamines is via MAO-A. The results have implications for clinical neurochemistry, experimental therapeutics, and computational models of catecholaminergic neurodegeneration. For instance, the greater susceptibility of DA than the other catecholamines to both MAO isoforms can help explain relatively high concentrations of the deaminated DA metabolite 3,4-dihydroxyphenylacetic acid than of the NE metabolite 3,4-dihydroxyphenylglycol in human plasma and urine. SIGNIFICANCE STATEMENT: Endogenous catecholamines are metabolized by monoamine oxidase (MAO)-A and -B, yielding the catecholaldehydes 3,4-dihydroxyphenylacetaldehyde (DOPAL) from dopamine (DA) and 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL) from norepinephrine (NE) and epinephrine (EPI). Based on measurements of DOPAL and DOPEGAL production, DA is a better substrate than NE or EPI for both MAO isoforms, and MAO-A is more efficient than MAO-B in metabolizing DA, NE, and EPI. MAO-A is the main route of intraneuronal metabolism of endogenous catecholamines.

HIF2α regulates the synthesis and release of epinephrine in the adrenal medulla

The adrenal gland and its hormones regulate numerous fundamental biological processes; however, the impact of hypoxia signaling on adrenal function remains poorly understood. Here, we reveal that deficiency of HIF (hypoxia inducible factors) prolyl hydroxylase domain protein-2 (PHD2) in the adrenal medulla of mice results in HIF2α-mediated reduction in phenylethanolamine N-methyltransferase (PNMT) expression, and consequent reduction in epinephrine synthesis. Simultaneous loss of PHD2 in renal erythropoietin (EPO)-producing cells (REPCs) stimulated HIF2α-driven EPO overproduction, excessive RBC formation (erythrocytosis), and systemic hypoglycemia, which is necessary and sufficient to enhance exocytosis of epinephrine from the adrenal medulla. Based on these results, we propose that the PHD2-HIF2α axis in the adrenal medulla regulates the synthesis of epinephrine, whereas in REPCs, it indirectly induces the release of this hormone. Our findings are also highly relevant to the testing of small molecule PHD inhibitors in phase III clinical trials for patients with renal anemia. KEY MESSAGES: HIF2α and not HIF1α modulates PNMT during epinephrine synthesis in chromaffin cells. The PHD2-HIF2α-EPO axis induces erythrocytosis and hypoglycemia. Reduced systemic glucose facilitates exocytosis of epinephrine from adrenal gland.

The Catecholaldehyde Hypothesis for the Pathogenesis of Catecholaminergic Neurodegeneration: What We Know and What We Do Not Know

3,4-Dihydroxyphenylacetaldehyde (DOPAL) is the focus of the catecholaldehyde hypothesis for the pathogenesis of Parkinson’s disease and other Lewy body diseases. The catecholaldehyde is produced via oxidative deamination catalyzed by monoamine oxidase (MAO) acting on cytoplasmic dopamine. DOPAL is autotoxic, in that it can harm the same cells in which it is produced. Normally, DOPAL is detoxified by aldehyde dehydrogenase (ALDH)-mediated conversion to 3,4-dihydroxyphenylacetic acid (DOPAC), which rapidly exits the neurons. Genetic, environmental, or drug-induced manipulations of ALDH that build up DOPAL promote catecholaminergic neurodegeneration. A concept derived from the catecholaldehyde hypothesis imputes deleterious interactions between DOPAL and the protein alpha-synuclein (αS), a major component of Lewy bodies. DOPAL potently oligomerizes αS, and αS oligomers impede vesicular and mitochondrial functions, shifting the fate of cytoplasmic dopamine toward the MAO-catalyzed formation of DOPAL—destabilizing vicious cycles. Direct and indirect effects of DOPAL and of DOPAL-induced misfolded proteins could “freeze” intraneuronal reactions, plasticity of which is required for neuronal homeostasis. The extent to which DOPAL toxicity is mediated by interactions with αS, and vice versa, is poorly understood. Because of numerous secondary effects such as augmented spontaneous oxidation of dopamine by MAO inhibition, there has been insufficient testing of the catecholaldehyde hypothesis in animal models. The clinical pathophysiological significance of genetics, emotional stress, environmental agents, and interactions with numerous proteins relevant to the catecholaldehyde hypothesis are matters for future research. The imposing complexity of intraneuronal catecholamine metabolism seems to require a computational modeling approach to elucidate clinical pathogenetic mechanisms and devise pathophysiology-based, individualized treatments.

Adrenal Hormone Interactions and Metabolism: A Single Sample Multi-Omics Approach

The adrenal gland is important for many physiological and pathophysiological processes, but studies are often restricted by limited availability of sample material. Improved methods for sample preparation are needed to facilitate analyses of multiple classes of adrenal metabolites and macromolecules in a single sample. A procedure was developed for preparation of chromaffin cells, mouse adrenals, and human chromaffin tumors that allows for multi-omics analyses of different metabolites and preservation of native proteins. To evaluate the new procedure, aliquots of samples were also prepared using conventional procedures. Metabolites were analyzed by liquid-chromatography with mass spectrometry or electrochemical detection. Metabolite contents of chromaffin cells and tissues analyzed with the new procedure were similar or even higher than with conventional methods. Catecholamine contents were comparable between both procedures. The TCA cycle metabolites, cis-aconitate, isocitate, and α-ketoglutarate were detected at higher concentrations in cells, while in tumor tissue only isocitrate and potentially fumarate were measured at higher contents. In contrast, in a broad untargeted metabolomics approach, a methanol-based preparation procedure of adrenals led to a 1.3-fold higher number of detected metabolites. The established procedure also allows for simultaneous investigation of adrenal hormones and related enzyme activities as well as proteins within a single sample. This novel multi-omics approach not only minimizes the amount of sample required and overcomes problems associated with tissue heterogeneity, but also provides a more complete picture of adrenal function and intra-adrenal interactions than previously possible.

Pharmacokinetics and pharmacodynamics of ampreloxetine, a novel, selective norepinephrine reuptake inhibitor, in symptomatic neurogenic orthostatic hypotension

Purpose

Ampreloxetine is a novel, selective, long-acting norepinephrine reuptake (NET) inhibitor being investigated as a once-daily oral treatment for symptomatic neurogenic orthostatic hypotension (nOH) in patients with autonomic synucleinopathies. The purpose of this study was to characterize the pharmacokinetic and pharmacodynamic profiles of ampreloxetine in this target population.

Methods

Patients with nOH were enrolled in a multicenter, phase II clinical trial of ampreloxetine (NCT02705755). They received escalating doses over 5 days in the clinical research unit, followed by 20 weeks of open-label treatment and then a 4-week withdrawal. As neurochemical biomarkers of NET inhibition, we assayed plasma concentrations of norepinephrine (NE) and its main intraneuronal metabolite 3,4-dihydroxyphenylglycol (DHPG) pre- and post-ampreloxetine.

Results

Thirty-four patients with nOH were enrolled. Plasma ampreloxetine concentrations increased with repeated escalating doses, with peak concentrations observed 6–9 h post-drug administration. The median ampreloxetine dose in the 20-week treatment phase was 10 mg once daily. Plasma ampreloxetine concentrations reached steady state by 2 weeks, with stable plasma levels over 24 h. No influence of age or renal function on ampreloxetine plasma concentrations was observed. On treatment, compared to baseline, plasma NE significantly increased by 71% (p < 0.005), plasma DHPG significantly declined by 22% (p < 0.05), and the NE:DHPG ratio significantly increased (p < 0.001).

Conclusions

Persistent elevation of plasma NE levels accompanied by reduced DHPG levels after ampreloxetine suggests reduced neuronal reuptake and metabolism of NE in postganglionic efferent sympathetic neurons. The findings are consistent with long-lasting NET inhibition, which may increase vasoconstrictor tone, supporting once-daily ampreloxetine dosing in patients with nOH.

The longevity gene mIndy (I'm Not Dead, Yet) affects blood pressure through sympathoadrenal mechanisms

Reduced expression of the plasma membrane citrate transporter INDY (acronym I’m Not Dead, Yet) extends life span in lower organisms. Deletion of the mammalian Indy (mIndy) gene in rodents improves metabolism via mechanisms akin to caloric restriction, known to lower blood pressure (BP) by sympathoadrenal inhibition. We hypothesized that mIndy deletion attenuates sympathoadrenal support of BP. Continuous arterial BP and heart rate (HR) were reduced in mINDY-KO mice. Concomitantly, urinary catecholamine content was lower, and the decreases in BP and HR by mIndy deletion were attenuated after autonomic ganglionic blockade. Catecholamine biosynthesis pathways were reduced in mINDY-KO adrenals using unbiased microarray analysis. Citrate, the main mINDY substrate, increased catecholamine content in pheochromocytoma cells, while pharmacological inhibition of citrate uptake blunted the effect. Our data suggest that deletion of mIndy reduces sympathoadrenal support of BP and HR by attenuating catecholamine biosynthesis. Deletion of mIndy recapitulates beneficial cardiovascular and metabolic responses to caloric restriction, making it an attractive therapeutic target.

Deletion of mIndy reduces blood pressure and heart rate by attenuating catecholamine biosynthesis and recapitulates beneficial cardiovascular and metabolic responses to caloric restriction.

HIF1α is a direct regulator of steroidogenesis in the adrenal gland

Endogenous steroid hormones, especially glucocorticoids and mineralocorticoids, derive from the adrenal cortex, and drastic or sustained changes in their circulatory levels affect multiple organ systems. Although hypoxia signaling in steroidogenesis has been suggested, knowledge on the true impact of the HIFs (Hypoxia-Inducible Factors) in the adrenocortical cells of vertebrates is scant. By creating a unique set of transgenic mouse lines, we reveal a prominent role for HIF1α in the synthesis of virtually all steroids in vivo. Specifically, mice deficient in HIF1α in adrenocortical cells displayed enhanced levels of enzymes responsible for steroidogenesis and a cognate increase in circulatory steroid levels. These changes resulted in cytokine alterations and changes in the profile of circulatory mature hematopoietic cells. Conversely, HIF1α overexpression resulted in the opposite phenotype of insufficient steroid production due to impaired transcription of necessary enzymes. Based on these results, we propose HIF1α to be a vital regulator of steroidogenesis as its modulation in adrenocortical cells dramatically impacts hormone synthesis with systemic consequences. In addition, these mice can have potential clinical significances as they may serve as essential tools to understand the pathophysiology of hormone modulations in a number of diseases associated with metabolic syndrome, auto-immunity or even cancer.

Mutation of the Cell Cycle Regulator p27kip1 Drives Pseudohypoxic Pheochromocytoma Development

Simple Summary

Pheochromocytomas and paragangliomas (PPGLs) can be subdivided into at least three different subgroups associated with different clinical manifestations and depending on the risk to metastasize. A shortage in human tumor material, the lack of a functional human cell line and very limited animal models were major drawbacks for PPGL research and consequently for the development of patient-tailored targeted therapies. We have previously reported that the MENX rat model develops pheochromocytoma with a full penetrance at the age of 8–10 months, however, it was unclear which human group the rat tumors modeled best. In order to characterize the rat pheochromocytomas, we analyzed gene expression, the catecholamine profile, TCA-cycle metabolism, methylation, angiogenesis, histology and mitochondrial ultrastructure. In all aspects, rat MENX pheochromocytomas resemble the features of the human pseudohypoxia group, the most aggressive one and in need of effective therapeutic approaches.

Abstract

Background: Pseudohypoxic tumors activate pro-oncogenic pathways typically associated with severe hypoxia even when sufficient oxygen is present, leading to highly aggressive tumors. Prime examples are pseudohypoxic pheochromocytomas and paragangliomas (p-PPGLs), neuroendendocrine tumors currently lacking effective therapy. Previous attempts to generate mouse models for p-PPGLs all failed. Here, we describe that the rat MENX line, carrying a Cdkn1b (p27) frameshift-mutation, spontaneously develops pseudohypoxic pheochromocytoma (p-PCC). Methods: We compared rat p-PCCs with their cognate human tumors at different levels: histology, immunohistochemistry, catecholamine profiling, electron microscopy, transcriptome and metabolome. The vessel architecture and angiogenic potential of pheochromocytomas (PCCs) was analyzed by light-sheet fluorescence microscopy ex vivo and multi-spectral optoacoustic tomography (MSOT) in vivo. Results: The analysis of tissues at various stages, from hyperplasia to advanced grades, allowed us to correlate tumor characteristics with progression. Pathological changes affecting the mitochrondrial ultrastructure where present already in hyperplasias. Rat PCCs secreted high levels of norepinephrine and dopamine. Transcriptomic and metabolomic analysis revealed changes in oxidative phosphorylation that aggravated over time, leading to an accumulation of the oncometabolite 2-hydroxyglutarate, and to hypermethylation, evident by the loss of the epigenetic mark 5-hmC. While rat PCC xenografts showed high oxygenation, induced by massive neoangiogenesis, rat primary PCC transcriptomes possessed a pseudohypoxic signature of high Hif2a, Vegfa, and low Pnmt expression, thereby clustering with human p-PPGL. Conclusion: Endogenous rat PCCs recapitulate key phenotypic features of human p-PPGLs. Thus, MENX rats emerge as the best available animal model of these aggressive tumors. Our study provides evidence of a link between cell cycle dysregulation and pseudohypoxia.

Sympathetic Markers are Different Between Clinical Responders and Nonresponders After Left Ventricular Assist Device Implantation

BACKGROUND

Clinical response to left ventricular assist devices (LVADs), as measured by health-related quality of life, varies among patients after implantation; however, it is unknown which pathophysiological mechanisms underlie differences in clinical response by health-related quality of life.

OBJECTIVE

The purpose of this study was to compare changes in sympathetic markers (β-adrenergic receptor kinase-1 [βARK1], norepinephrine [NE], and 3,4-dihydroxyphenylglycol [DHPG]) between health-related quality of life clinical responders and nonresponders from pre- to post-LVAD implantation.

METHODS

We performed a secondary analysis on a subset of data from a cohort study of patients from pre- to 1, 3, and 6 months after LVAD implantation. Clinical response was defined as an increase of 5 points or higher on the Kansas City Cardiomyopathy Questionnaire Clinical Summary score from pre- to 6 months post-LVAD implantation. We measured plasma βARK1 level with an enzyme-linked immunosorbent assay and plasma NE and DHPG levels with high-performance liquid chromatography with electrochemical detection. Latent growth curve modeling was used to compare the trajectories of markers between groups.

RESULTS

The mean (SD) age of the sample (n = 39) was 52.9 (13.2) years, and most were male (74.4%) and received LVADs as bridge to transplantation (69.2%). Preimplantation plasma βARK1 levels were significantly higher in clinical responders (n = 19) than in nonresponders (n = 20) (P = .001), but change was similar after LVAD (P = .235). Preimplantation plasma DHPG levels were significantly lower in clinical responders than in nonresponders (P = .002), but the change was similar after LVAD (P = .881). There were no significant differences in plasma NE levels.

CONCLUSIONS

Preimplantation βARK1 and DHPG levels are differentiating factors between health-related quality of life clinical responders and nonresponders to LVAD, potentially signaling differing levels of sympathetic stimulation underlying clinical response.

Hormonal Blood Pressure Regulationduring General Anesthesia Usinga Standardized Propofol Dosagein Children and Adolescents SeemsNot to Be Affected by Body Weight

Obesity in pediatric surgical patients is a challenge for the anesthesiologist. Despite potentially beneficial properties, propofol might also induce hypotension. This study examined whether a dose adjustment in overweight children could avoid hypotension and if there would be differences regarding hormonal regulation in children under anesthesia. Fifty-nine children undergoing surgery under general anesthesia were enrolled in this prospective observational trial. Participants were allocated into two groups according to their BMI. The induction of anesthesia was conducted using propofol (“overweight”: 2 mg/kgBW, “regular”: 3.2 mg/kgBW). The maintenance of anesthesia was conducted as total intravenous anesthesia. Hormone levels of renin, angiotensin II, aldosterone, copeptin, norepinephrine and epinephrine were assessed at different timepoints. Blood pressure dropped after the administration of propofol in both groups, with a nadir 2 min after administration—but without a significant difference in the strength of reduction between the two groups. As a reaction, an increase in the plasma levels of renin, angiotensin and aldosterone was observed, while levels of epinephrine, norepinephrine and copeptin dropped. By adjusting the propofol dosage in overweight children, the rate of preincision hypotension could be reduced to the level of normal-weight patients with a non-modified propofol dose. The hormonal counter regulation was comparable in both groups. The release of catecholamines and copeptin as an indicator of arginine vasopressin seemed to be inhibited by propofol.

Pheochromocytoma and Paraganglioma Patients With Poor Survival Often Show Brown Adipose Tissue Activation

CONTEXT

Pheochromocytomas/paragangliomas (PPGLs) are neuroendocrine tumors that can secrete norepinephrine (NE). Brown adipose tissue (BAT) activation is mediated through the action of NE on β-adrenoceptors (β-ARs). In some malignancies, BAT activation is associated with higher cancer activity.

OBJECTIVE

To study the relationship between BAT activation and PPGL clinical outcomes.

DESIGN

A retrospective case-control study that included 342 patients with PPGLs who underwent 18F-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography (18F-FDG PET/CT) imaging at the National Institutes of Health (NIH). We excluded all patients with parasympathetic tumors and those who underwent 18F-FDG PET/CT after PPGL resection. Scans of 205 patients were reviewed by 2 blinded nuclear medicine physicians; 16 patients had BAT activation on 18F-FDG PET/CT [7.80%; age 27.50 (15.00-45.50) years; 10 female/6 male; body mass index [BMI] 24.90 [19.60-25.35] kg/m2). From the remaining 189 patients, we selected 36 matched controls (age 34.4 [25.4-45.5] years; 21 female/15 male; BMI 25.0 [22.0-26.0] kg/m2).

PRIMARY OUTCOME MEASURE

Overall survival.

RESULTS

The presence of active BAT on 18F-FDG PET/CT was associated with decreased overall survival when compared with the control group (HRz 5.80; 95% CI, 1.05-32.05; P = 0.02). This association remained significant after adjusting for the SDHB mutation. Median plasma NE in the BAT group was higher than the control group [4.65 vs 0.55 times above the upper limit of normal; P < 0.01]. There was a significant association between higher plasma NE levels and mortality in PPGLs in both groups.

CONCLUSIONS

Our findings suggest that the detection of BAT activity in PPGL patients is associated with higher mortality. We suggest that BAT activation could either be reflecting or contributing to a state of increased host stress that may predict poor outcome in metastatic PPGL.

The catecholaldehyde hypothesis: where MAO fits in

Monoamine oxidase (MAO) plays a central role in the metabolism of the neurotransmitters dopamine, norepinephrine, and serotonin. This brief review focuses on 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is the immediate product of MAO acting on cytoplasmic dopamine. DOPAL is toxic; however, normally DOPAL is converted via aldehyde dehydrogenase (ALDH) to 3,4-dihydroxyphenylacetic acid (DOPAC), which rapidly exits the neurons. In addition to vesicular uptake of dopamine via the vesicular monoamine transporter (VMAT), the two-enzyme sequence of MAO and ALDH keeps cytoplasmic dopamine levels low. Dopamine oxidizes readily to form toxic products that could threaten neuronal homeostasis. The catecholaldehyde hypothesis posits that diseases featuring catecholaminergic neurodegeneration result from harmful interactions between DOPAL and the protein alpha-synuclein, a major component of Lewy bodies in diseases such as Parkinson disease, dementia with Lewy bodies, and pure autonomic failure. DOPAL potently oligomerizes alpha-synuclein, and alpha-synuclein oligomers impede vesicular functions, shifting the fate of cytoplasmic dopamine toward MAO-catalyzed formation of DOPAL-a vicious cycle. When MAO deaminates dopamine to form DOPAL, hydrogen peroxide is generated; and DOPAL, hydrogen peroxide, and divalent metal cations react to form hydroxyl radicals, which peroxidate lipid membranes. Lipid peroxidation products in turn inhibit ALDH, causing DOPAL to accumulate-another vicious cycle. MAO inhibition decreases DOPAL formation but concurrently increases the spontaneous oxidation of dopamine, potentially trading off one form of toxicity for another. These considerations rationalize a neuroprotection strategy based on concurrent treatment with an MAO inhibitor and an anti-oxidant.

Ganglionic and ovarian action of acetylcholine during diestrous II in rats. Neuroendocrine control of the luteal regression

Our aim was to investigate if acetylcholine (Ach), added to the celiac ganglion-superior ovarian nerve-ovary system (CG-SON-ovary) or in ovary incubations, modifies the release of progesterone (P₄), androstenedione (A₂), dopamine (DA), norepinephrine (NE), gonadotropin-releasing hormone (GnRH), and alters the expression of 3β-hydroxysteroid dehydrogenase (3β-HSD), 20α-hydroxysteroid dehydrogenase (20α-HSD), and apoptotic genes in ovarian tissue during the diestrous II (DII) in rats. The CG-SON-ovary system or the ovary alone were removed and placed into separate cuvettes both containing Krebs-Ringer solution (control groups). In experimental groups, 10^-6 M Ach was added into the ganglion compartment or into the ovary compartment. P₄, A₂ and GnRH were measured by RIA, mRNA expression by RT-PCR, and catecholamines by HPLC. In addition, a routine histological technique was applied. In ex-vivo system, 10^-6 M Ach into the ganglion compartment decreased P₄ and NE release, altered 3β-HSD and 20α-HSD expression, and decreased bax/bcl-2 ratio, while increasing the release of A₂ and DA, and bcl-2 expression. In ovary incubations, 10^-6 M Ach decreased P₄ and GnRH release, decreased 3β-HSD and bcl-2 expression, increased A₂ release, increased 20α-HSD and bax expression, and the bax/bcl-2 ratio, and induced disorganization of the corpus luteum structure. The peripheral nervous system protected the ovary from the apoptotic mechanisms while in the ovary incubation the effect was reversed. Our results indicate that Ach in DII regulates steroidogenesis and apoptosis in the ovary, by modulating the concentration of neurotransmitters. In vivo, an alteration in the extrinsic cholinergic innervation of the ovary could disrupt the endocrine control of the reproductive function.

Adipocyte β-arrestin-2 is essential for maintaining whole body glucose and energy homeostasis

β-Arrestins are major regulators of G protein-coupled receptor-mediated signaling processes. Their potential roles in regulating adipocyte function in vivo remain unexplored. Here we report the novel finding that mice lacking β-arrestin-2 (barr2) selectively in adipocytes show significantly reduced adiposity and striking metabolic improvements when consuming excess calories. We demonstrate that these beneficial metabolic effects are due to enhanced signaling through adipocyte β3-adrenergic receptors (β3-ARs), indicating that barr2 represents a potent negative regulator of adipocyte β3-AR activity in vivo. Interestingly, essentially all beneficial metabolic effects caused by adipocyte barr2 deficiency are absent in adipocyte barr2-PRDM16 double KO mice, indicating that the metabolic improvements caused by the lack of barr2 in adipocytes are mediated by the browning/beiging of white adipose tissue. Our data support the novel concept that 'G protein-biased' β3-AR agonists that do not promote β3-AR/barr2 interactions may prove useful for the treatment of obesity and related metabolic disorders.

Overexpression of a Neuronal Type Adenylyl Cyclase (Type 8) in Sinoatrial Node Markedly Impacts Heart Rate and Rhythm

Heart rate (HR) and HR variability (HRV), predictors of over-all organism health, are widely believed to be driven by autonomic input to the sinoatrial node (SAN), with sympathetic input increasing HR and reducing HRV. However, variability in spontaneous beating intervals in isolated SAN tissue and single SAN cells, devoid of autonomic neural input, suggests that clocks intrinsic to SAN cells may also contribute to HR and HRV in vivo. We assessed contributions of both intrinsic and autonomic neuronal input mechanisms of SAN cell function on HR and HRV via in vivo, telemetric EKG recordings. This was done in both wild type (WT) mice, and those in which adenylyl cyclase type 8 (ADCY8), a main driver of intrinsic cAMP-PKA-Ca²⁺ mediated pacemaker function, was overexpressed exclusively in the heart (TG^AC8). We hypothesized that TG^AC8 mice would: (1) manifest a more coherent pattern of HRV in vivo, i.e., a reduced HRV driven by mechanisms intrinsic to SAN cells, and less so to modulation by autonomic input and (2) utilize unique adaptations to limit sympathetic input to a heart with high levels of intrinsic cAMP-Ca²⁺ signaling. Increased adenylyl cyclase (AC) activity in TG^AC8 SAN tissue was accompanied by a marked increase in HR and a concurrent marked reduction in HRV, both in the absence or presence of dual autonomic blockade. The marked increase in intrinsic HR and coherence of HRV in TG^AC8 mice occurred in the context of: (1) reduced HR and HRV responses to β-adrenergic receptor (β-AR) stimulation; (2) increased transcription of genes and expression of proteins [β-Arrestin, G Protein-Coupled Receptor Kinase 5 (GRK5) and Clathrin Adaptor Protein (Dab2)] that desensitize β-AR signaling within SAN tissue, (3) reduced transcripts or protein levels of enzymes [dopamine beta-hydorxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT)] required for catecholamine production in intrinsic cardiac adrenergic cells, and (4) substantially reduced plasma catecholamine levels. Thus, mechanisms driven by cAMP-PKA-Ca²⁺ signaling intrinsic to SAN cells underlie the marked coherence of TG^AC8 mice HRV. Adaptations to limit additional activation of AC signaling, via decreased neuronal sympathetic input, are utilized to ensure the hearts survival and prevent Ca²⁺ overload.

The Significant Reduction or Complete Eradication of Subcutaneous and Metastatic Lesions in a Pheochromocytoma Mouse Model after Immunotherapy Using Mannan-BAM, TLR Ligands, and Anti-CD40

Therapeutic options for metastatic pheochromocytoma/paraganglioma (PHEO/PGL) are limited. Here, we tested an immunotherapeutic approach based on intratumoral injections of mannan-BAM with toll-like receptor ligands into subcutaneous PHEO in a mouse model. This therapy elicited a strong innate immunity-mediated antitumor response and resulted in a significantly lower PHEO volume compared to the phosphate buffered saline (PBS)-treated group and in a significant improvement in mice survival. The cytotoxic effect of neutrophils, as innate immune cells predominantly infiltrating treated tumors, was verified in vitro. Moreover, the combination of mannan-BAM and toll-like receptor ligands with agonistic anti-CD40 was associated with increased mice survival. Subsequent tumor re-challenge also supported adaptive immunity activation, reflected primarily by long-term tumor-specific memory. These results were further verified in metastatic PHEO, where the intratumoral injections of mannan-BAM, toll-like receptor ligands, and anti-CD40 into subcutaneous tumors resulted in significantly less intense bioluminescence signals of liver metastatic lesions induced by tail vein injection compared to the PBS-treated group. Subsequent experiments focusing on the depletion of T cell subpopulations confirmed the crucial role of CD8⁺ T cells in inhibition of bioluminescence signal intensity of liver metastatic lesions. These data call for a new therapeutic approach in patients with metastatic PHEO/PGL using immunotherapy that initially activates innate immunity followed by an adaptive immune response.

LC–MS/MS method for quantification of 3,4-dihydroxyphenylglycol, a norepinephrine metabolite in plasma and brain regions

Aim: To evaluate suitability of the LC–MS/MS method to quantify 3,4-dihydroxyphenylglycol (DHPG) that is used as a biomarker for monoamine oxidase (MAO) inhibition. Methods: DHPG was extracted using alumina basic cartridges and quantified on a triple quadrupole mass spectrometer using negative electrospray ionization, without the use of derivatization reagents. Results: Modulation of DHPG levels was observed following administration of selective and nonselective MAO inhibitors and results were in correlation with historical MAO inhibition potential of compounds. Conclusion: The proposed method is sensitive enough to measure plasma DHPG levels and DHPG can be used as a biomarker to assess MAO inhibition potential of new therapeutic agents.

Impact of Extrinsic and Intrinsic Hypoxia on Catecholamine Biosynthesis in Absence or Presence of Hif2α in Pheochromocytoma Cells

Pheochromocytomas and paragangliomas (PPGLs) with activated pseudohypoxic pathways are associated with an immature catecholamine phenotype and carry a higher risk for metastasis. For improved understanding of the underlying mechanisms we investigated the impact of hypoxia and pseudohypoxia on catecholamine biosynthesis in pheochromocytoma cells naturally lacking Hif2α (MPC and MTT) or expressing both Hif1α and Hif2α (PC12). Cultivation under extrinsic hypoxia or in spheroid culture (intrinsic hypoxia) increased cellular dopamine and norepinephrine contents in all cell lines. To distinguish further between Hif1α- and Hif2α-driven effects we expressed Hif2α in MTT and MPC-mCherry cells (naturally lacking Hif2α). Presence of Hif2α resulted in similarly increased cellular dopamine and norepinephrine under hypoxia as in the control cells. Furthermore, hypoxia resulted in enhanced phosphorylation of tyrosine hydroxylase (TH). A specific knockdown of Hif1α in PC12 diminished these effects. Pseudohypoxic conditions, simulated by expression of Hif2α under normoxia resulted in increased TH phosphorylation, further stimulated by extrinsic hypoxia. Correlations with PPGL tissue data led us to conclude that catecholamine biosynthesis under hypoxia is mainly mediated through increased phosphorylation of TH, regulated as a short-term response (24–48 h) by HIF1α. Continuous activation of hypoxia-related genes under pseudohypoxia leads to a HIF2α-mediated phosphorylation of TH (permanent status).

Primary fibroblast co-culture stimulates growth and metabolism in Sdhb-impaired mouse pheochromocytoma MTT cells

Pheochromocytomas and paragangliomas (PGLs) due to mutations of succinate dehydrogenase (SDH) B, a subunit of the SDH complex with a role in the Krebs cycle and the respiratory chain, tend to be larger at diagnosis and more prone to metastatic disease than other tumors. This presentation contrasts with the behavior of some cell line models of SDHB impairment, which show reduced growth compared to wild type. We hypothesize that reduced growth of SDHB-impaired monolayer culture models might reflect lack of support from sources within the tumor microenvironment. The present study therefore investigates how the microenvironment, modeled here by fibroblast co-culture, modulates cell metabolism, growth and invasion in an Sdhb-impaired mouse pheochromocytoma cell line. We employed two different constructs of short hairpin RNA to knockdown Sdhb and compared growth in a monolayer with and without fibroblast co-culture. Sdhb-silenced cells showed functional impairment of SDH with elevated succinate to fumarate ratio and decreased oxidative capacity. Cell growth was delayed with an increase in doubling time of 2 h or 20 h. Clonogenic cell survival and viability, on the other hand, were either unchanged or increased compared to control. In standard monolayer culture, no differences in pro-metastatic features were present. Co-culture with primary mouse fibroblast reversed the difference of proliferation between control and Sdhb knockdown but was unable to significantly influence invasiveness under these culture conditions. Metabolic studies identified that lactate secreted by fibroblasts was taken up preferentially by Sdhb-silenced cells. In summary, the present study identified a potential role for the tumor microenvironment in influencing phenotypic features of SDHB-mutated PGLs, providing a basis for the use of therapies targeted towards the tumor microenvironment.

Measurement of plasma norepinephrine and 3,4-dihydroxyphenylglycol: method development for a translational research study

Objective

Norepinephrine (NE), a sympathetic neurotransmitter, is often measured in plasma as an index of sympathetic activity. To better understand NE dynamics, it is important to measure its principal metabolite, 3,4-dihydroxyphenylglycol (DHPG), concurrently. Our aim was to present a method, developed in the course of a translational research study, to measure NE and DHPG in human plasma using high performance liquid chromatography with electrochemical detection (HPLC-ED).

Results

After pre-purifying plasma samples by alumina extraction, we used HPLC-ED to separate and quantify NE and DHPG. In order to remove uric acid, which co-eluted with DHPG, a sodium bicarbonate wash was added to the alumina extraction procedure, and we oxidized the column eluates followed by reduction because catechols are reversibly oxidized whereas uric acid is irreversibly oxidized. Average recoveries of plasma NE and DHPG were 35.3 ± 1.0% and 16.3 ± 1.1%, respectively, and there was no detectable uric acid. Our estimated detection limits for NE and DHPG were approximately 85 pg/mL (0.5 pmol/mL) and 165 pg/mL (0.9 pmol/mL), respectively. The measurement of NE and DHPG in human plasma has wide applicability; thus, we describe a method to quantify plasma NE and DHPG in a laboratory setting as a useful tool for translational and clinical research.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3352-3) contains supplementary material, which is available to authorized users.

Adrenomedullary function, obesity and permissive influences of catecholamines on body mass in patients with chromaffin cell tumours

BACKGROUND

Obesity-associated activation of sympathetic nervous outflow is well documented, whereas involvement of dysregulated adrenomedullary hormonal function in obesity is less clear. This study assessed relationships of sympathoadrenal function with indices of obesity and influences of circulating catecholamines on body mass.

METHODS

Anthropometric and clinical data along with plasma and 24-h urine samples were collected from 590 volunteers and 1368 patients tested for phaeochromocytoma and paraganglioma (PPGL), among whom tumours were diagnosed in 210 individuals.

RESULTS

Among patients tested for PPGL, those with tumours less often had a body mass index (BMI) above 30 kg/m² (12 vs. 31%) and more often a BMI under 25 kg/m² (56 vs. 32%) than those without tumours (P < 0.0001). Urinary outputs of catecholamines in patients with PPGL were negatively related to BMI (r = -0.175, P = 0.0133). Post-operative weight gain (P < 0.0001) after resection of PPGL was positively related to presurgical tumoural catecholamine output (r = 0.257, P = 0.0101). Higher BMI in men and women and percent body fat in women of the volunteer group were associated with lower plasma concentrations and urinary outputs of adrenaline and metanephrine, the former indicating obesity-related reduced adrenaline secretion and the latter obesity-related reduced adrenomedullary adrenaline stores. Daytime activity was associated with substantial increases in urinary adrenaline and noradrenaline excretion, with blunted responses in obese subjects.

CONCLUSIONS

The findings in patients with PPGL support an influence of high circulating catecholamines on body weight. Additional associations of adrenomedullary dysfunction with obesity raise the possibility of a permissive influence of the adrenal medulla on the regulation of body weight.

Resting heart rate variability and exercise capacity in Type 1 diabetes

People with type 1 diabetes (T1D) have lower exercise capacity (V̇O_2max) than their age‐matched nondiabetic counterparts (CON), which might be related to cardiac autonomic dysfunction. We examined whether Heart Rate Variability (HRV; indicator of cardiac autonomic modulation) was associated with exercise capacity in those with and without T1D. Twenty‐three participants with uncomplicated T1D and 17 matched CON were recruited. Heart rate (HR; ECG), blood pressure (BP; finger photo‐plethysmography), and respiratory rate (respiratory belt) were measured during baseline, paced‐breathing and clinical autonomic reflex tests (CARTs); deep breathing, lying‐to‐stand, and Valsalva maneuver. Baseline and paced‐breathing ECG were analyzed for HRV (frequency‐domain). Exercise capacity was determined during an incremental cycle ergometer test while V̇O₂, 12‐lead ECG, and BP were measured. In uncomplicated T1D, resting HR was elevated and resting HRV metrics were reduced, indicative of altered cardiac parasympathetic modulation; this was generally undetected by the CARTs. However, BP and plasma catecholamines were not different between groups. In T1D, V̇O_2max tended to be lower (P = 0.07) and HR reserve was lower (P < 0.01). Resting Total Power (TP) had stronger positive associations with V̇O_2max (R² ≥ 0.3) than all other traditional indicators such as age, resting HR, and self‐reported exercise (R² = 0.042–0.3) in both T1D and CON. Alterations in cardiac autonomic modulation are an early manifestation of uncomplicated T1D. Total Power was associated with reduced exercise capacity regardless of group, and these associations were generally stronger than traditional indicators.

Independent and interactive effects of incremental heat strain, orthostatic stress, and mild hypohydration on cerebral perfusion

The purpose of this study was to identify the dose-dependent effects of heat strain and orthostasis [via lower body negative pressure (LBNP)], with and without mild hypohydration, on systemic function and cerebral perfusion. Eleven men (means ± SD: 27 ± 7 y; body mass 77 ± 6 kg), resting supine in a water-perfused suit, underwent progressive passive heating [0.5°C increments in core temperature (T_c; esophageal to +2.0°C)] while euhydrated (EUH) or hypohydrated (HYPO; 1.5-2% body mass deficit). At each thermal state, mean cerebral artery blood velocity (MCAv_mean; transcranial Doppler), partial pressure of end-tidal carbon dioxide ([Formula: see text]), heart rate (HR) and mean arterial blood pressure (MAP; photoplethysmography) were measured continuously during LBNP (0, -15, -30, and -45 mmHg). Four subjects became intolerant before +2.0°C T_c, unrelated to hydration status. Without LBNP, decreases in [Formula: see text] accounted fully for reductions in MCAv_mean across all T_c. With LBNP at heat tolerance (+1.5 or +2.0°C), [Formula: see text] accounted for 69 ± 25% of the change in MCAv_mean. The HYPO condition did not affect MCAv_mean or any cardiovascular variables during combined LBNP and passive heat stress (all P > 0.13). These findings indicate that hypocapnia accounted fully for the reduction in MCAv_mean when passively heat stressed in the absence of LBNP and for two- thirds of the reduction when at heat tolerance combined with LBNP. Furthermore, when elevations in T_c are matched, mild hypohydration does not influence cerebrovascular or cardiovascular responses to LBNP, even when stressed by a combination of hyperthermia and LBNP.

The microenvironment induces collective migration in SDHB-silenced mouse pheochromocytoma spheroids

Pheochromocytomas (Pheos) and paragangliomas (PGLs) are neuroendocrine tumors. Approximately 30-40% of Pheos/PGLs are due to germline mutations in one of the susceptibility genes, including those encoding the succinate dehydrogenase subunits A-D (SDHA-D). Up to 2/3 of patients affected by SDHB mutated Pheo/PGL develop metastatic disease with no successful cure at present. Here, for the first time, we evaluated the effects of SDHB silencing in a three dimension (3D) culture using spheroids of a mouse Pheo cell line silenced or not (wild type/wt/control) for the SDHB subunit. We investigated the role of the microenvironment on spheroid growth and migration/invasion by co-culturing SDHB-silenced or wt spheroids with primary cancer-activated fibroblasts (CAFs). When spheroids were co-cultured with fibroblasts, SDHB-silenced cells showed a significant increase in matrigel invasion as demonstrated by the computation of the migratory areas (P < 0.001). Moreover, cells detaching from the SDHB-silenced spheroids moved collectively, unlike the cells of wt spheroids that moved individually. Additionally, SDHB-silenced spheroids developed long filamentous formations along which clusters of cells migrated far away from the spheroid, whereas these structures were not present in wt spheroids. We found that lactate, largely secreted by CAFs, plays a specific role in promoting migration only of SDHB-silenced cells. In this study, we demonstrated that SDHB silencing per se increases tumor cell migration/invasion and that microenvironment, as represented by CAFs, plays a pivotal role in enhancing collective migration/invasion in Pheo SDHB-silenced tumor cells, suggesting their role in increasing the tumor metastasizing potential.

Plasma Catechols After Eating Olives

Olives contain 3,4‐dihydroxyphenyl compounds (catechols)—especially 3,4‐dihydroxyphenylethanol (DOPET)—that have therapeutic potential as nutraceuticals. Whether olive ingestion affects plasma levels of free (unconjugated) catechols has been unknown. Arm venous blood was sampled before and 15, 30, 45, 60, 120, 180, and 240 min after six healthy volunteers ate 10 Kalamata olives. Catechols were assayed by alumina extraction followed by liquid chromatography with series electrochemical detection. Plasma DOPET increased to 18.5 times baseline at 30 min (area under the curve (AUC) 39.2 ± 9.2 pmol‐min/mL, P = 0.008). 3,4‐Dihydroxyphenylacetic acid (DOPAC) increased markedly (peak 37.4 times baseline, AUC 23,490 ± 4,151 pmol‐min/mL, P = 0.002). The sum of 10 catechols increased 12‐fold (P < 0.0001). Eating olives produces large‐magnitude increases in plasma levels of catechols, mainly DOPAC. DOPET seems to go undergo extensive hepatic metabolism to DOPAC.

β-Adrenergic Responsiveness in the Type 2 Diabetic Heart: Effects on Cardiac Reserve

Type 2 diabetes (T2D) is associated with reduced cardiac reserve and aerobic capacity. Altered myocardial autonomic nervous regulation has been demonstrated in humans with diabetes (indirectly) and animal models (directly).

PURPOSE

This study aimed to determine the chronotopic and inotropic response of the type 2 diabetic heart to β-adrenergic stimulation.

METHODS

Eight people with uncomplicated T2D and seven matched controls performed a dual-energy x-ray absorptiometry scan and V˙O2peak test. Plasma catecholamines were determined at rest and during peak exercise. On a second visit, HR and left ventricular contractility were assessed using echocardiography during supine rest, parasympathetic blockade (atropine), and during incremental β-adrenergic stimulation (dobutamine).

RESULTS

V˙O2peak and HR reserve were lower in T2D (P < 0.05) as expected. Both groups increased norepinephrine comparably (P = 0.23) during peak exercise; however, epinephrine increased less in the T2D group (P < 0.05). The dobutamine dose required to achieve 85% of age-predicted maximal HR was 36% higher in CON (P < 0.05). Resting HR was higher (P < 0.01) and stroke volume indexed to fat free mass was smaller (P < 0.05) in T2D. During dobutamine infusion the response (% change) in HR, end-diastolic volumeFFM, stroke volume, ejection fraction, and cardiac output were not different between the groups. However, HR was higher (P < 0.01) and end-diastolic volume indexed to fat free mass (P < 0.01), stroke volumeFFM (P < 0.01), ejection fraction (P < 0.05), and stroke work (P < 0.01) were lower in T2D.

CONCLUSIONS

Although the type 2 diabetic heart worked at smaller volumes, the HR and contractile response to β-adrenergic stimulation were unaffected by diabetes. The reduced cardiac reserve observed in uncomplicated T2D was not explained by impaired myocardial sympathetic responsiveness but may reflect changes in the loading conditions or function of the diabetic left ventricle.

Endovascular Renal Denervation in End-Stage Kidney Disease Patients: Cardiovascular Protection-A Proof-of-Concept Study

Introduction

Sympathetic neural activation is markedly increased in end-stage kidney disease (ESKD). Catheter-based renal denervation (RDN) reduces sympathetic overactivity and blood pressure in resistant hypertension. We investigated the effect of RDN on sympathetic neural activation and left ventricular mass in patients with ESKD.

Methods

Nine ESKD (6 hemodialysis and 3 peritoneal dialysis) patients with dialysis vintage of ≥11 months were treated with RDN (EnligHTN system). Data were obtained on a nondialysis day; at baseline, 1, 3, and 12 months post-RDN.

Results

At baseline sympathetic neural activation measured by muscle sympathetic nervous activity (MSNA) and plasma norepinephrine concentrations were markedly elevated. Left ventricular hypertrophy (LVH) was evident in 8 of the 9 patients. At 12 months post-RDN, blind analysis revealed that MSNA_frequency (–12.2 bursts/min¹, 95% CI [–13.6, –10.7]) and LV mass (–27 g/m², 95% CI [–47, –8]) were reduced. Mean ambulatory BP (systolic: –24 mm Hg, 95% CI [–42, –5] and diastolic: –13 mm Hg, 95% CI [–22, –4]) was also reduced at 12 months. Office BP was reduced as early as 1 month (systolic: –25 mm Hg, 95% CI [–45, –5] and diastolic: –13 mm Hg, 95% CI [–24, –1]). Both ambulatory and office BP had clinically significant reductions in at least 50% of patients out to 12 months.

Discussion

Catheter-based RDN significantly reduced MSNA and LV mass as well as systemic BP in this group of patients with ESKD.

Concerted regulation of renal plasma flow and glomerular filtration rate by renal dopamine and NOS I in rats on high salt intake

Under high sodium intake renal dopamine (DA) increases while NOS I expression in macula densa cells (MD) decreases. To explore whether renal DA and NOS I, linked to natriuresis and to the stability of the tubuloglomerular feedback, respectively, act in concert to regulate renal plasma flow (RPF) and glomerular filtration rate (GFR). Male Wistar rats were studied under a normal sodium intake (NS, NaCl 0.24%) or a high sodium intake (HS, NaCl 1% in drinking water) during the 5 days of the study. For the last two days, the specific D1-like receptor antagonist SCH 23390 (1 mg kg bwt-1 day-1, sc) or a vehicle was administered. HS intake increased natriuresis, diuresis, and urinary DA while it decreased cortical NOS I expression (P < 0.05 vs. NS), Nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in MD (P < 0.001 vs. NS) and cortical nitrates+nitrites (NOx) production (NS 2.04 ± 0.22 vs. HS 1.28 ± 0.10 nmol mg protein-1, P < 0.01). Treatment with SCH 23390 to rats on HS sharply decreased hydroelectrolyte excretion (P < 0.001 vs. HS) while NOS I expression, NADPH-d activity and NOx production increased (P < 0.05 vs. HS for NOS I and P < 0.001 vs. HS for NADPH-d and NOx). SCH 23390 increased RPF and GFR in HS rats (P < 0.01 HS+SCH vs. HS). It did not cause variations in NS rats. Results indicate that when NS intake is shifted to a prolonged high sodium intake, renal DA through the D1R, and NOS I in MD cells act in concert to regulate RPF and GFR to stabilize the delivery of NaCl to the distal nephron.

Homovanillic acid in CSF of mild stage Parkinson's disease patients correlates with motor impairment

In Parkinson's disease (PD), several efforts have been spent in order to find biochemical parameters able to identify the progression of the pathological processes at the basis of the disease. It is already known that advanced PD patients manifesting dyskinesia are featured by the high homovanillic acid (HVA)/dopamine (DA) ratio, suggesting the increased turnover of DA in these patients. Less clear is whether similar changes affect mild and moderate stages of the disease (between 1 and 2.5 of Hoehn & Yahr -H&Y- stage). Hence, here we tested whether cerebrospinal fluid (CSF) concentrations of DA and its major metabolites, either 3,4-dihydroxyphenylacetic acid (DOPAC) or HVA, correlate with motor performance in mild and moderate PD patients. CSF samples were collected after 2 days of anti-PD drugs washout, via lumbar puncture (LP) performed 130 min following administration of oral levodopa (LD) dose (200 mg). LP timing was determined in light of our previous tests clarifying that 2 h after oral LD administration CSF DA concentration reaches a plateau, which was un-respective of PD stage or duration. DA, DOPAC and HVA were assayed by high performance liquid chromatography in a group of 19 patients, distributed in two groups on the basis of the H&Y stage with a cut-off of 1.5. In these PD patients, HVA was correlated with DOPAC (R = 0,56, p < 0,01) and both HVA and DOPAC CSF levels increased in parallel with the motor impairment. More importantly, HVA correlated with motor impairment measured by the Unified Parkinson's Disease Score -III (UPDRS) (R = 0.61; p < 0.0001). The present findings showed the early alteration of the DA pre-synaptic machinery, as documented by the progressive increase of CSF HVA concentrations, which also correlated with PD motor impairment. Therefore, we suggest the potential use of measuring the CSF HVA level as a possible biomarker of PD stage changes in order to monitor the effectiveness of PD-modifying pharmacological therapies.

Morphology, Biochemistry, and Pathophysiology of MENX-Related Pheochromocytoma Recapitulate the Clinical Features

Pheochromocytomas (PCCs) are tumors arising from neural crest-derived chromaffin cells. There are currently few animal models of PCC that recapitulate the key features of human tumors. Because such models may be useful for investigations of molecular pathomechanisms and development of novel therapeutic interventions, we characterized a spontaneous animal model (multiple endocrine neoplasia [MENX] rats) that develops endogenous PCCs with complete penetrance. Urine was longitudinally collected from wild-type (wt) and MENX-affected (mutant) rats and outputs of catecholamines and their O-methylated metabolites determined by mass spectrometry. Adrenal catecholamine contents, cellular ultrastructure, and expression of phenylethanolamine N-methyltransferase, which converts norepinephrine to epinephrine, were also determined in wt and mutant rats. Blood pressure was longitudinally measured and end-organ pathology assessed. Compared with wt rats, mutant animals showed age-dependent increases in urinary outputs of norepinephrine (P = .0079) and normetanephrine (P = .0014) that correlated in time with development of tumor nodules, increases in blood pressure, and development of hypertension-related end-organ pathology. Development of tumor nodules, which lacked expression of N-methyltransferase, occurred on a background of adrenal medullary morphological and biochemical changes occurring as early as 1 month of age and involving increased adrenal medullary concentrations of dense cored vesicles, tissue contents of both norepinephrine and epinephrine, and urinary outputs of metanephrine, the metabolite of epinephrine. Taken together, MENX-affected rats share several biochemical and pathophysiological features with PCC patients. This model thus provides a suitable platform to study the pathogenesis of PCC for preclinical translational studies aimed at the development of novel therapies for aggressive forms of human tumors.

Arterio-venous differences in cord levels of catecholamines, glucose, lactate and blood gases

BACKGROUND

Norepinephrine (NE) and epinephrine (EPI) levels are higher in cord arterial blood relative to venous blood, consistent with active mechanisms of placental-maternal clearance. There are no contemporary studies of cord arteriovenous blood levels of sulfated and non-sulfated catechols.

AIM

To assess the arteriovenous differences in cord blood levels of dopamine (DA), the sulfated catecholamines and their sulfated and non-sulfated metabolites. To correlate levels of oxygen, H+/CO2, and glucose with cord catecholamine levels.

METHODS

Fifty-seven term infants, delivered by elective cesarean section, were recruited. Cord arterial and venous blood was sampled; levels of glucose, lactate, blood gases, six catechols and their sulfated conjugates were measured.

RESULTS

With one exception (DOPA sulfate), mean cord arterial levels of sulfated and non-sulfated catechols were significantly higher than venous levels. Arterial lactate and glucose levels were independently associated with NE levels, but only lactate was associated with levels of EPI and DA.

CONCLUSION

This study establishes that in vivo metabolic parameters of hypoxia, respiratory and metabolic acidosis are associated with catecholamine levels, a key relationship for perinatal adaptation and homeostasis, and findings that are consistent with in vitro studies of the regulators of catecholamine secretion.

CHARACTERISTICS AND OUTCOMES OF METASTATIC SDHB AND SPORADIC PHEOCHROMOCYTOMA/PARAGANGLIOMA: AN NATIONAL INSTITUTES OF HEALTH STUDY

OBJECTIVE

Overall about 10 to 20% of pheochromocytomas/paragangliomas (PHEOs/PGLs) are metastatic, with higher metastatic potential observed in succinate dehydrogenase subunit B/fumarate hydratase (SDHB/FH)-related tumors. Due to the improved availability of biochemical and genetic testing and the frequent use of anatomical/functional imaging, there is currently a higher detection rate of metastatic PHEO/PGL.

METHODS

A retrospective analysis of 132 patients (27 children, 105 adults) with metastatic PHEO/PGL diagnosed and treated from 2000 to 2014 was conducted.

RESULTS

Seventy-seven (58%) males and 55 (42%) females were included; 39 (30%) have died, with no sex preference. Seventy-three (55%) patients had SDHB mutations; 59 (45%) patients had apparently sporadic tumors (AST). SDHB patients had an average age at primary tumor diagnosis of 31 ± 16 years compared to 40 ± 15 years in AST patients (P<.001). The average metastatic interval (MI) decreased with increasing age in both SDHB and AST patients (P = .013 for both). Only 16% of all primary tumors were smaller than 4.5 cm. Eleven percent of patients had biochemically silent disease, more with SDHB. Of SDHB patients, 23% had metastatic tumors at first diagnosis, compared to 15% of AST patients. Five- and 10-year survival rates were significantly better for metastatic AST than SDHB patients (P = .01). Overall survival was significantly different between children and adults (P = .037); this was mostly attributed to the SDHB patients, in whom children had statistically significantly longer survival than adults (P = .006). The deceased patients all died due to the PHEO/PGL and mainly had noradrenergic phenotypes.

CONCLUSION

In children, metastatic PHEOs/PGLs are mainly due to SDHB mutations; in adults they are equally distributed between in SDHB mutations and AST, with better 5- and 10-year survival rates for ASTs. In SDHB patients, children survive longer than adults. Primary metastatic tumors, most presenting as noradrenergic PGLs, are larger than 4.5 cm in >80% of patients. The frequency of metastatic tumors from primary AST increases with age, including a decreased MI compared to SDHB tumors. These results support several recommendations that are summarized in the Discussion.

Comparison of Monoamine Oxidase Inhibitors in Decreasing Production of the Autotoxic Dopamine Metabolite 3,4-Dihydroxyphenylacetaldehyde in PC12 Cells

According to the catecholaldehyde hypothesis, the toxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL) contributes to the loss of nigrostriatal dopaminergic neurons in Parkinson's disease. Monoamine oxidase-A (MAO-A) catalyzes the conversion of intraneuronal dopamine to DOPAL and may serve as a therapeutic target. The "cheese effect"-paroxysmal hypertension evoked by tyramine-containing foodstuffs-limits clinical use of irreversible MAO-A inhibitors. Combined MAO-A/B inhibition decreases DOPAL production in rat pheochromocytoma PC12 cells, but whether reversible MAO-A inhibitors or MAO-B inhibitors decrease endogenous DOPAL production is unknown. We compared the potencies of MAO inhibitors in attenuating DOPAL production and examined possible secondary effects on dopamine storage, constitutive release, synthesis, and auto-oxidation. Catechol concentrations were measured in cells and medium after incubation with the irreversible MAO-A inhibitor clorgyline, three reversible MAO-A inhibitors, or the MAO-B inhibitors selegiline or rasagiline for 180 minutes. Reversible MAO-A inhibitors were generally ineffective, whereas clorgyline (1 nM), rasagiline (500 nM), and selegiline (500 nM) decreased DOPAL levels in the cells and medium. All three drugs also increased dopamine and norepinephrine, decreased 3,4-dihydroxyphenylalanine, and increased cysteinyl-dopamine concentrations in the medium, suggesting increased vesicular uptake and constitutive release, decreased dopamine synthesis, and increased dopamine spontaneous oxidation. In conclusion, clorgyline, rasagiline, and selegiline decrease production of endogenous DOPAL. At relatively high concentrations, the latter drugs probably lose their selectivity for MAO-B. Possibly offsetting increased formation of potentially toxic oxidation products and decreased formation of DOPAL might account for the failure of large clinical trials of MAO-B inhibitors to demonstrate slowing of neurodegeneration in Parkinson's disease.

Documenting stress in caregivers of transplantation patients: initial evidence of HPA dysregulation

There is growing evidence linking caregiver stress with an increased risk for morbidity and mortality. While the emotional and practical burden experienced by caregivers is well established, the physiological changes that may affect the caregiver's health are less understood. This study sought to compare self-reported stress, anxiety and depression along with neuroendocrine and immune markers of stress among adult caregivers of allogeneic hematopoietic stem cell transplantation patients during the acute transplant recovery period to matched non-caregivers controls. Biomarkers and self-reported data were collected at three points during the patient's HSCT: (1) before transplant, (2) after initial transplantation discharge (±7 days) and (3) 6 weeks after initial transplantation discharge. Mixed linear modeling was used to examine differences by group and time. Twenty-one caregivers and 20 controls completed all study procedures. The majority of caregivers were female (57% or 57.1%) and married (95.2%), with a mean age of 52 ± 11.4 years. Caregiver perceived stress, anxiety and depression scores were significantly higher than controls (p < 0.001) with effect sizes (ES) ranging from 1.37 to 1.80 and they did not change over time (p > 0.05) for either group. Caregivers had significantly lower serum cortisol levels than controls at both discharge (p = 0.013; ES = 0.81) and 6 weeks after discharge (p = 0.028; ES = 0.72) but exhibited no significant relationship between self-reported stress and serum cortisol. In addition, caregivers showed a significant inverse relationship between stress and epinephrine levels (r(s)=-0.654, p = 0.021). These findings support the evidence of the caregiving experience being stressful. The counter-intuitive relationship between cortisol and epinephrine might suggest dysregulation of the HPA axis and central nervous system but additional research on the physiological impact of caregiving is warranted.

Valproic acid enhances neuronal differentiation of sympathoadrenal progenitor cells

The antiepileptic drug valproic acid (VPA) has been shown to influence the neural differentiation and neurite outgrowth of neural stem cells. Sympathoadrenal progenitor cells share properties with neural stem cells and are considered a potential cell source in the treatment of neurodegenerative diseases. The present study therefore aims at modulating the neural differentiation potential of these cells by treatment with the histone deacetylase inhibitor VPA. We studied the epigenetic effects of VPA in two culture conditions: suspension conditions aimed to expand adrenomedullary sympathoadrenal progenitors within free-floating chromospheres and adherent cell cultures optimized to derive neurons. Treatment of chromospheres with VPA may launch neuronal differentiation mechanisms and improve their neurogenic potential upon transplantation. However, also transplantation of differentiated functional neurons could be beneficial. Treating chromospheres for 7 days with clinically relevant concentrations of VPA (2 mm) revealed a decrease of neural progenitor markers Nestin, Notch2 and Sox10. Furthermore, VPA initiated catecholaminergic neuronal differentiation indicated by upregulation of the neuronal marker β-III-tubulin, the dopaminergic transcription factor Pitx3 and the catecholaminergic enzymes TH and GTPCH. In adherent neural differentiation conditions, VPA treatment improved the differentiation of sympathoadrenal progenitor cells into catecholaminergic neurons with significantly elevated levels of nor- and epinephrine. In conclusion, similar to neural stem cells, VPA launches differentiation mechanisms in sympathoadrenal progenitor cells that result in increased generation of functional neurons. Thus, data from this study will be relevant to the potential use of chromaffin progenitors in transplantation therapies of neurodegenerative diseases.

Maternal and fetal factors which influence cord blood glucose levels in term infants delivered by cesarean section

AIM

To assess factors contributing to cord venous glucose homeostasis in term infants delivered by elective cesarean section.

METHODS

Observational study of women-infant pairs at delivery. Biochemical and clinical data were collected about factors which might affect the levels of glucose, lactate, norepinephrine, epinephrine, cortisol, human growth hormone, glucagon, and insulin.

RESULTS

In the context of this data-set, three models explained a substantial amount regarding the variation: 79% of the variation in cord glucose levels is explained by levels of maternal glucose, cord venous pH, and cord lactate; 77% of the variation of cord lactate is explained by levels of cord venous pH, valine, maternal lactate and glucose, and cord norepinephrine; and 71% of the variation in cord norepinephrine is explained by levels of cord venous pO2, maternal lactate, cord insulin, cord GABA (gamma-aminobutyric acid), cord lactate, cord epinephrine, cord norepinephrine sulfate, and cord valine.

CONCLUSIONS

Term infants delivered by cesarean section are relatively hyperinsulinemic (insulin:glucose ratio of 2.4) and glucose levels are strongly associated with maternal glucose levels, cord pO2, and lactate levels. There were no associations with levels of cord glucose and levels of cortisol, epinephrine and lactate, which have been shown to be important contributors to postnatal glucose homeostasis in some infant groups.

Norepinephrine preferentially modulates memory CD8 T cell function inducing inflammatory cytokine production and reducing proliferation in response to activation

BACKGROUND

Norepinephrine (NE) is one of the primary catecholamines of the sympathetic nervous system released during a stress response and plays an important role in modulating immune function. NE binds to the adrenergic receptors on immune cells, including T cells, resulting in either suppressed or enhanced function depending on the type of cell, activation status of the cell, duration of NE exposure and concentration of NE. Here, we aim to analyze the effects of NE on the functionality of naïve (Tn), central memory (Tcm) and effector memory (Tem) CD8 T cells.

METHODS

We isolated CD8 T cell subsets from healthy human adults and treated cells in vitro with NE (1×10(-6)M) for 16h; we then stimulated NE treated and untreated CD8 T cell subsets with antibodies for CD3 and CD28 for 24 and 72h. We assessed the level of beta-2 adrenergic receptor (ADRB2) expression in these cells as well as global gene expression changes in NE treated Tcm cells by microarray analysis. Altered expressed genes after NE treatment were identified and further confirmed by RT-qPCR, and by ELISA for protein changes. We further determined whether the observed NE effects on memory CD8 T cells are mediated by ADRB2 using specific adrenergic receptor agonist and antagonists. Finally, we examined the levels of mRNA and protein of the NE-induced genes in healthy adults with high serum levels of NE (>150pg/mL) compared to low levels (<150pg/mL).

RESULTS

We found that memory (Tcm and Tem) CD8 T cells expressed a significantly higher level of ADRB2 compared to naïve cells. Consequently, memory CD8 T cells were significantly more sensitive than naïve cells to NE induced changes in gene expressions in vitro. Global gene expression analysis revealed that NE induced an elevated expression of inflammatory cytokines and chemokines in resting and activated memory CD8 T cells in addition to a reduced expression of growth-related cytokines. The effects of NE on memory CD8 T cells were primarily mediated by ADRB2 as confirmed by the adrenergic receptor agonist and antagonist assays. Finally, individuals with high serum levels of NE had similar elevated gene expressions observed in vitro compared to the low NE group.

CONCLUSIONS

Our results demonstrate that NE preferentially modulates the functions of memory CD8 T cells by inducing inflammatory cytokine production and reducing activation-induced memory CD8 T cell expansion.

Defective renal dopamine function and sodium-sensitive hypertension in adult ovariectomized Wistar rats: role of the cytochrome P-450 pathway

We have previously shown that ovariectomy in adult Wistar rats under normal sodium (NS) intake results in an overexpression of the total Na(+)-K(+)-ATPase (NKA) α1-subunit (Di Ciano LA, Azurmendi PJ, Toledo JE, Oddo EM, Zotta E, Ochoa F, Arrizurieta EE, Ibarra FR. Clin Exp Hypertens 35: 475-483, 2013). Upon high sodium (HS) intake, ovariectomized (oVx) rats developed defective NKA phosphorylation, a decrease in sodium excretion, and an increment in mean blood pressure (MBP). Since NKA phosphorylation is modulated by dopamine (DA), the aim of this study was to compare the intracellular response of the renal DA system leading to NKA phosphorylation upon sodium challenge in intact female (IF) and oVx rats. In IF rats, HS caused an increase in urinary DA and sodium, in NKA phosphorylation state, in cytochrome P-4504A (CYP4A) expression, and in 20-HETE production, while MBP kept normal. Blockade of the D1 receptor (D1R) with the D1-like receptor antagonist SCH 23390 in IFHS rats shifted NKA into a more dephosphorylated state, decreased sodium excretion by 50%, and increased MBP. In oVxNS rats, D1R expression was reduced and D3R expression was increased, and under HS intake sodium excretion was lower and MBP higher than in IFHS rats (both P < 0.05), NKA was more dephosphorylated than in IFHS, and CYP4A expression or 20-HETE production did not change. Blockade of D1R in oVxHS rats changed neither NKA phosphorylation state nor sodium excretion or MBP. D2R and PKCα expression did not vary among groups. The alteration of the renal DA system produced by ovariectomy could account for the defective NKA phosphorylation, the inefficient excretion of sodium load, and the development of salt-sensitive hypertension.

Catecholamine autotoxicity. Implications for pharmacology and therapeutics of Parkinson disease and related disorders

Several neurodegenerative diseases involve loss of catecholamine neurons-Parkinson disease is a prototypical example. Catecholamine neurons are rare in the nervous system, and why they are vulnerable in PD and related disorders has been mysterious. Accumulating evidence supports the concept of "autotoxicity"-inherent cytotoxicity of catecholamines and their metabolites in the cells in which they are produced. According to the "catecholaldehyde hypothesis" for the pathogenesis of Parkinson disease, long-term increased build-up of 3,4-dihydroxyphenylacetaldehyde (DOPAL), the catecholaldehyde metabolite of dopamine, causes or contributes to the eventual death of dopaminergic neurons. Lewy bodies, a neuropathologic hallmark of PD, contain precipitated alpha-synuclein. Bases for the tendency of alpha-synuclein to precipitate in the cytoplasm of catecholaminergic neurons have also been mysterious. Since DOPAL potently oligomerizes and aggregates alpha-synuclein, the catecholaldehyde hypothesis provides a link between alpha-synucleinopathy and catecholamine neuron loss in Lewy body diseases. The concept developed here is that DOPAL and alpha-synuclein are nodes in a complex nexus of interacting homeostatic systems. Dysfunctions of several processes, including decreased vesicular sequestration of cytoplasmic catecholamines, decreased aldehyde dehydrogenase activity, and oligomerization of alpha-synuclein, lead to conversion from the stability afforded by negative feedback regulation to the instability, degeneration, and system failure caused by induction of positive feedback loops. These dysfunctions result from diverse combinations of genetic predispositions, environmental exposures, stress, and time. The notion of catecholamine autotoxicity has several implications for treatment, disease modification, and prevention. Conversely, disease modification clinical trials would provide key tests of the catecholaldehyde hypothesis.