Chromaffin Cells Research Articles

Novel miRNA-inducing drugs enable differentiation of retinoic acid-resistant neuroblastoma cells.

Tumor cell heterogeneity in neuroblastoma, a pediatric cancer arising from neural crest-derived progenitor cells, poses a significant clinical challenge. In particular, unlike adrenergic (ADRN) neuroblastoma cells, mesenchymal (MES) cells are resistant to chemotherapy and retinoid therapy and thereby significantly contribute to relapses and treatment failures. Previous research suggested that overexpression or activation of miR-124, a neurogenic microRNA with tumor suppressor activity, can induce the differentiation of retinoic acid-resistant neuroblastoma cells. Leveraging our established screen for miRNA-modulatory small molecules, we validated PP121, a dual inhibitor of tyrosine and phosphoinositide kinases, as a robust inducer of miR-124. A combination of PP121 and BDNF-activating bufalin synergistically arrests proliferation, induces differentiation, and maintains the differentiated state of MES SK-N-AS cells for 8 weeks. RNA-seq and deconvolution analyses revealed a collapse of the ADRN core regulatory circuitry (CRC) and the emergence of novel CRCs associated with chromaffin cells and Schwann cell precursors. Using a similar protocol, we differentiated and maintained MES neuroblastoma GI-ME-N and SH-EP cell lines, as well as glioblastoma LN-229 and U-251 cell lines, for over 16 weeks. In conclusion, our novel protocol suggests a promising treatment for therapy-resistant cancers of the nervous system. Moreover, these long-lived, differentiated cells provide valuable models for studying mechanisms underlying differentiation, maturation, and senescence.

Unusual neuroendocrine tumor in unusual site: a case report and review of literature

Paragangliomas (PGL) are uncommon tumors that develop in the extra-adrenal chromaffin cells of the autonomic nervous system. They are usually found in the retroperitoneum along the abdominal para-aortic region. PGL arising near the pancreas are extremely rare. These tumors can be difficult to diagnose as they can resemble more common pancreatic tumors, making it challenging for clinicians, radiologists, and pathologists alike. In this report, we describe a case of PGL that originated in the pancreaticoduodenal groove, which was initially diagnosed as a neuroendocrine tumor arising from the second part of the duodenum. The patient underwent pancreas-preserving surgery to remove the tumour.

Mouse developmental defects, but not paraganglioma tumorigenesis, upon conditional Complex II loss in early Sox10+ cells.

In humans, loss of heterozygosity for defective alleles of any of the four subunits of mitochondrial tricarboxylic acid cycle enzyme succinate dehydrogenase (SDH, also Complex II of the electron transport chain) can lead to paraganglioma tumors in neuroendocrine cells. With the goal of developing mouse models of this rare disorder, we have developed various SDH conditional loss strategies. Based on recent lineage tracing studies, we hypothesized that conditional SDHC loss in early embryogenesis during migration of primordial neural crest cells that form the susceptible chromaffin cells of the adrenal medulla might induce paraganglioma. We triggered low levels of detectable SDHC loss in Sox10+ cells at E11.5 of mouse development. We report that, rather than developing adrenal medulla paraganglioma (pheochromocytoma), offspring survived with evidence of neural crest cell dysfunction. Phenotypes included mild lower extremity gait anomalies suggestive of neural tube closure defects and patches of unpigmented fur consistent with neural crest-derived melanocyte dysfunction. These defects were not observed in mice lacking Sdhc knockout. Our results add to existing data suggesting that, unlike humans, even early embryonic (Sox10-driven) SDHx loss is inadequate to trigger paraganglioma in mice of the genetic backgrounds that have been investigated. Instead, low levels of tricarboxylic acid cycle-deficient neural crest cells cause mild developmental defects in hind limb and melanocyte function. This new model may be of interest for studies of metabolism during early neural crest cell development.

Deletion of the α2δ-1 calcium channel subunit increases excitability of mouse chromaffin cells.

High voltage-gated Ca2+ channels (HVCCs) shape the electrical activity and control hormone release in most endocrine cells. HVCCs are multi-subunit protein complexes formed by the pore-forming α1 and the auxiliary β, α2δ and γ subunits. Four genes code for the α2δ isoforms. At the mRNA level, mouse chromaffin cells (MCCs) express predominantly the CACNA2D1 gene coding for the α2δ-1 isoform. Here we show that α2δ-1 deletion led to ∼60% reduced HVCC Ca2+ influx with slower inactivation kinetics. Pharmacological dissection showed that HVCC composition remained similar in α2δ-1-/- MCCs compared to wild-type (WT), demonstrating that α2δ-1 exerts similar functional effects on all HVCC isoforms. Consistent with reduced HVCC Ca2+ influx, α2δ-1-/- MCCs showed reduced spontaneous electrical activity with action potentials (APs) having a shorter half-maximal duration caused by faster rising and decay slopes. However, the induced electrical activity showed opposite effects with α2δ-1-/- MCCs displaying significantly higher AP frequency in the tonic firing mode as well as an increase in the number of cells firing AP bursts compared to WT. This gain-of-function phenotype was caused by reduced functional activation of Ca2+-dependent K+ currents. Additionally, despite the reduced HVCC Ca2+ influx, the intracellular Ca2+ transients and vesicle exocytosis or endocytosis were unaltered in α2δ-1-/- MCCs compared to WT during sustained stimulation. In conclusion, our study shows that α2δ-1 genetic deletion reduces Ca2+ influx in cultured MCCs but leads to a paradoxical increase in catecholamine secretion due to increased excitability. KEY POINTS: Deletion of the α2δ-1 high voltage-gated Ca2+ channel (HVCC) subunit reduces mouse chromaffin cell (MCC) Ca2+ influx by ∼60% but causes a paradoxical increase in induced excitability. MCC intracellular Ca2+ transients are unaffected by the reduced HVCC Ca2+ influx. Deletion of α2δ-1 reduces the immediately releasable pool vesicle exocytosis but has no effect on catecholamine (CA) release in response to sustained stimuli. The increased electrical activity and CA release from MCCs might contribute to the previously reported cardiovascular phenotype of patients carrying α2δ-1 loss-of-function mutations.

Paraganglioma in the bladder wall: A case report

AbstractBackgroundPheochromocytomas are tumors originating from chromaffin cells and producing catecholamines. In 10%–20% of cases, these tumors act outside of the adrenal medulla, defining conglomerates named paragangliomas. Bladder paraganglioma is a rare tumor and accounts for less than 0.06% of all bladder neoplasms and less than 1% of all pheochromocytomas, with the first case described in 1953. The clinical procedure given by 47%–77% of the overall number of cases, consists of headache 48.1%, tachycardia 43.4%, hypertension 54.7%, hematuria 47.2%, and visual alterations.Case PresentationThe article reports a case of a patient whose lesion was identified in the lateral wall of the bladder during a prostate ultrasonography exam, and was subsequently treated surgically with a partial cystectomy. The aim of this study is to detail the diagnosis and treatment of a patient with bladder paraganglioma.ConclusionFrom the overall study conducted in this article, it is possible to conclude that paraganglioma requires adequate diagnostic and therapeutic methods. These methods include ultrasounds and computed tomography scans, followed by cystoscopy with visualization and biopsy of the lesion, and resection of the lesion.

Ultrastructural changes in the adrenal gland in terms of age and gender-related

Objectives: The adrenal glands are endocrine organs that synthesise hormones with crucial functions in the body. This irreplaceable structure performs multiple functions, from metabolism of carbohydrates, fats and proteins to sex development. Any disorder concerning the adrenal glands can give rise to life-threatening conditions. The aging process inevitably affects the adrenal glands. The effects of ageing are marked by a rise in cortisol secretion in the zona fasciculata and a decrease in androgen secretion in the zona reticularis. Elevated cortisol levels in the blood disturb most bodily systems in favour of catabolism, amplifying the cellular decline and destruction that accompanies ageing. The deterioration of the adrenal glands relates not just to spongiocytes and chromaffin cells, but also to the endothelium, which enables circulation. It is clear that a decline in vascular function will have a negative impact on endocrine activities. Our study aims to explore the influence of ageing on the adrenal glands in rats, analysing sex-specific ultrastructural scales. Materials and Methods: A total of 28 Sprague-Dawley rats, 14 males and 14 females, were planned to be used in the study. Of these 28 rats, 4 females and 4 males will constitute the control group. The rats in the control group will be approximately 10 weeks old, and the rats in the experimental group, which will represent the aged group, will be 19 weeks old. All animals in the study will be anaesthetised and then sacrificed by removal of the heart. The right and left common carotid arteries were removed from the sacrificed animals. Collected vessels prepared for TEM examination. For each animal, at least four TEM images were taken from four different sections from the same block. Results: Our findings demonstrate that the ageing process not only affects spongiocytes within the adrenal gland, but also contributes to the deterioration of endothelial cells. As anticipated, our results indicate the presence of senescence and apoptosis in endothelial cells. The observed vascular separations and ruptures are due to the endothelial deterioration. Spongiocytes experienced hypertrophy to compensate for the functional deficiencies following a decrease in their number due to ageing. Elevated levels of lipofuscin, lipid droplets, and lysosomes were discovered in spongiocytes. Impaired endothelium potentially contributes to certain changes in spongiocytes. Conclusions: While ageing-related changes appear similar in both genders, males tend to be more impacted.

1215 Cardiovascular Compromise and Hypertensive Crisis Secondary to Phaeochromocytoma

Abstract Phaeochromocytoma is a rare tumour of the chromaffin cells in the adrenal medulla, which secretes catecholamines. While associated with genetic disorders e.g., MEN-2, they tend to occur sporadically, and are often initially asymptomatic, found incidentally on imaging. Classical symptoms of Phaeochromocytoma include headaches, sweating, and palpitations, with sustained or paroxysmal hypertension which is refractory to a cocktail of antihypertensives. A variety of presentations have been reported in the literature including, but not limited to colitis, intracerebral haemorrhage, and PRES syndrome. We present a case of a 64-year-old man with an incidental left adrenal nodule. This radiologically indeterminate lesion was initially asymptomatic. Secretion studies revealed elevated metadrenaline levels, and an MIBG scan with positive avidity unveiled the lesion's pheochromocytoma nature. Whilst awaiting surgical intervention, the patient required emergency admission with a hypertensive crisis, presenting with left-sided flank pain and a blood pressure peaking at 220mmHg systolic. ECG findings were consistent with a myocardial infarction-like picture, and echocardiogram demonstrated regional wall motion abnormalities. CT coronary angiography revealed no significant coronary arterial disease – confirming that the patient’s presentation was in fact secondary to the pheochromocytoma. Pre-operative optimization is crucial for safe surgery. After the crisis, surgery was delayed by 6 weeks for cardiac rehabilitation. The patient was admitted a week before the procedure for optimal haemodynamics. Adrenalectomy proceeded as planned after alpha-blockade. A structured endocrine surgery clinic follow-up was established to assess the patient's ongoing recovery, and cardiovascular status. This case highlights cardiovascular implications of phaeochromocytoma, stressing a multidisciplinary approach for hypertensive crises and optimising outcomes.

Characterisation of an Adult Zebrafish Model for SDHB-Associated Phaeochromocytomas and Paragangliomas.

Phaeochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumours arising from chromaffin cells. Pathogenic variants in the gene succinate dehydrogenase subunit B (SDHB) are associated with malignancy and poor prognosis. When metastases arise, limited treatment options are available. The pathomechanism of SDHB-associated PPGL remains largely unknown, and the lack of suitable models hinders therapy development. Germline heterozygous SDHB pathogenic variants predispose to developing PPGLs with a life-long penetrance of around 50%. To mimic the human disease phenotype, we characterised adult heterozygous sdhb mutant zebrafish as a potential model to study SDHB-related PPGLs. Adult sdhb mutant zebrafish did not develop an obvious tumour phenotype and were anatomically and histologically like their wild-type siblings. However, sdhb mutants showed significantly increased succinate levels, a major hallmark of SDHB-related PPGLs. While basal activity was increased during day periods in mutants, mitochondrial complex activity and catecholamine metabolite levels were not significantly different. In conclusion, we characterised an adult in vivo zebrafish model, genetically resembling human carriers. Adult heterozygous sdhb mutants mimicked their human counterparts, showing systemic elevation of succinate levels despite the absence of a tumour phenotype. This model forms a promising basis for developing a full tumour phenotype and gaining knowledge of the pathomechanism behind SDHB-related PPGLs.

A PACAP-activated network for secretion requires coordination of Ca2+ influx and Ca2+ mobilization.

Chromaffin cells of the adrenal medulla transduce sympathetic nerve activity into stress hormone secretion. The two neurotransmitters principally responsible for coupling cell stimulation to secretion are acetylcholine and pituitary adenylate activating polypeptide (PACAP). In contrast to acetylcholine, PACAP evokes a persistent secretory response from chromaffin cells. However, the mechanisms by which PACAP acts are poorly understood. Here, it is shown that PACAP induces sustained increases in cytosolic Ca2+ which are disrupted when Ca2+ influx through L-type channels is blocked or internal Ca2+ stores are depleted. PACAP liberates stored Ca2+ via inositol trisphosphate receptors (IP3Rs) on the endoplasmic reticulum (ER), thereby functionally coupling Ca2+ mobilization to Ca2+ influx and supporting Ca2+-induced Ca2+-release. These Ca2+ influx and mobilization pathways are unified by an absolute dependence on phospholipase C epsilon (PLCε) activity. Thus, the persistent secretory response that is a defining feature of PACAP activity, in situ, is regulated by a signaling network that promotes sustained elevations in intracellular Ca2+ through multiple pathways.

Comparative Histological study of Adrenal Gland at pre and post maturation stage in locally domestic Cats

Object of this study was to describe the histological composition of the adrenal gland in immature and adult local domestic cats. Twenty four healthy cats, as twelve immature aged 2-3 months and twelve adult aged 11-12 months were used. Post euthanized of all cats, their abdominal dissected, identified their adrenal glands and taken carefully. Proper specimens for histological assessment from glands were obtained and after fixation and processing routinely, thin sections prepared and stained. Histological results illustrated, in both ages of the cat, a connective tissue capsule encircled the gland. Two zones of tissues were represent the gland parenchyma including medullary region that hold chromaffin cells, and outer cortex which composed of glomerular, fasciculate, and reticular zones, which contain cells that differ in shape and arrangement. According to data analysis that related to measurements of basic structures of gland, it was revealed that significant differences in most them between the left and right gland as well as between both ages of cats. In conclusion, the study confirmed that the adrenal gland in immature cats showed a distinguish in formation of all basic structure of the gland despite the difference in the thickness of those structure from that of adult cats.

Multi-omic analysis of SDHB-deficient pheochromocytomas and paragangliomas identifies metastasis and treatment-related molecular profiles.

Hereditary SDHB-mutant pheochromocytomas (PC) and paragangliomas (PG) are rare tumours with a high propensity to metastasize although their clinical behaviour is unpredictable. To characterize the genomic landscape of these tumours and identify metastasis biomarkers, we performed multi-omic analysis on 94 tumours from 79 patients using seven molecular methods. Sympathetic (chromaffin cell) and parasympathetic (non-chromaffin cell) PCPG had distinct molecular profiles reflecting their cell-of-origin and biochemical profile. TERT and ATRX-alterations were associated with metastatic PCPG and these tumours had an increased mutation load, and distinct transcriptional and telomeric features. Most PCPG had quiet genomes with some rare co-operative driver events observed, including EPAS1/HIF-2α mutations. Two mechanisms of acquired resistance to DNA alkylating chemotherapies were also detected - MGMT overexpression and mismatch repair-deficiency causing hypermutation. Our comprehensive multi-omic analysis of SDHB-mutant PCPG therefore identified features of metastatic disease and treatment response, expanding our understanding of these rare neuroendocrine tumours.

Modulating Ca2+ influx into adrenal chromaffin cells with short-duration nanosecond electric pulses

Isolated bovine adrenal chromaffin cells exposed to single 2-, 4-, or 5-ns pulses undergo a rapid, transient rise in intracellular Ca2+ mediated by Ca2+ entry via voltage-gated Ca2+ channels (VGCCs), mimicking the activation of these cells in vivo by acetylcholine. However, pulse durations 150 ns or longer elicit larger amplitude and longer-lived Ca2+ responses due to Ca2+ influx via both VGCCs and a yet to be identified plasma membrane pathway(s). To further our understanding of the differential effects of ultrashort versus longer pulse durations on Ca2+ influx, chromaffin cells were loaded with calcium green-1 and exposed to single 3-, 5-, 11-, 25-, or 50-ns pulses applied at their respective Ca2+ activation threshold electric fields. Increasing pulse duration from 3 or 5 ns to only 11 ns was sufficient to elicit increased amplitude and longer-lived Ca2+ responses in the majority of cells, a trend that continued as pulse duration increased to 50 ns. The amplification of Ca2+ responses was not the result of Ca2+ release from intracellular stores and was accompanied by a decreased effectiveness of VGCC inhibitors to block the responses and a reduced reliance on extracellular Na+ and membrane depolarization to evoke the responses. Inhibitors of pannexin channels, P2X receptors, or non-selective cation channels failed to attenuate 50-ns-elicited Ca2+ responses, ruling out these Ca2+-permeable channels as secondary Ca2+ entry pathways. Analytical calculations and numerical modeling suggest that the parameter that best determines the response of chromaffin cells to increasing pulse durations is the time the membrane charges to its peak voltage. These results highlight the pronounced sensitivity of a neuroendocrine cell to pulse durations differing by only tens of nanoseconds, which has important implications for the future development of nanosecond pulse technologies enabling electrostimulation applications for spatially focused and graded in vivo neuromodulation.

Mechanical Strain Induces and Increases Vesicular Release Monitored by Microfabricated Stretchable Electrodes

AbstractExocytosis involving the fusion of intracellular vesicles with cell membrane, is thought to be modulated by the mechanical cues in the microenvironment. Single‐cell electrochemistry can offer unique information about the quantification and kinetics of exocytotic events; however, the effects of mechanical force on vesicular release have been poorly explored. Herein, we developed a stretchable microelectrode with excellent electrochemical stability under mechanical deformation by microfabrication of functionalized poly(3,4‐ethylenedioxythiophene) conductive ink, which achieved real‐time quantitation of strain‐induced vesicular exocytosis from a single cell for the first time. We found that mechanical strain could cause calcium influx via the activation of Piezo1 channels in chromaffin cell, initiating the vesicular exocytosis process. Interestingly, mechanical strain increases the amount of catecholamines released by accelerating the opening and prolonging the closing of fusion pore during exocytosis. This work is expected to provide revealing insights into the regulatory effects of mechanical stimuli on vesicular exocytosis.

Mechanical Strain Induces and Increases Vesicular Release Monitored by Microfabricated Stretchable Electrodes.

Exocytosis involving the fusion of intracellular vesicles with cell membrane, is thought to be modulated by the mechanical cues in the microenvironment. Single-cell electrochemistry can offer unique information about the quantification and kinetics of exocytotic events; however, the effects of mechanical force on vesicular release have been poorly explored. Herein, we developed a stretchable microelectrode with excellent electrochemical stability under mechanical deformation by microfabrication of functionalized poly(3,4-ethylenedioxythiophene) conductive ink, which achieved real-time quantitation of strain-induced vesicular exocytosis from a single cell for the first time. We found that mechanical strain could cause calcium influx via the activation of Piezo1 channels in chromaffin cell, initiating the vesicular exocytosis process. Interestingly, mechanical strain increases the amount of catecholamines released by accelerating the opening and prolonging the closing of fusion pore during exocytosis. This work is expected to provide revealing insights into the regulatory effects of mechanical stimuli on vesicular exocytosis.

Clathrin mediates membrane fission and budding by constricting membrane pores

Membrane budding, which underlies fundamental processes like endocytosis, intracellular trafficking, and viral infection, is thought to involve membrane coat-forming proteins, including the most observed clathrin, to form Ω-shape profiles and helix-forming proteins like dynamin to constrict Ω-profiles’ pores and thus mediate fission. Challenging this fundamental concept, we report that polymerized clathrin is required for Ω-profiles’ pore closure and that clathrin around Ω-profiles’ base/pore region mediates pore constriction/closure in neuroendocrine chromaffin cells. Mathematical modeling suggests that clathrin polymerization at Ω-profiles’ base/pore region generates forces from its intrinsically curved shape to constrict/close the pore. This new fission function may exert broader impacts than clathrin’s well-known coat-forming function during clathrin (coat)-dependent endocytosis, because it underlies not only clathrin (coat)-dependent endocytosis, but also diverse endocytic modes, including ultrafast, fast, slow, bulk, and overshoot endocytosis previously considered clathrin (coat)-independent in chromaffin cells. It mediates kiss-and-run fusion (fusion pore closure) previously considered bona fide clathrin-independent, and limits the vesicular content release rate. Furthermore, analogous to results in chromaffin cells, we found that clathrin is essential for fast and slow endocytosis at hippocampal synapses where clathrin was previously considered dispensable, suggesting clathrin in mediating synaptic vesicle endocytosis and fission. These results suggest that clathrin and likely other intrinsically curved coat proteins are a new class of fission proteins underlying vesicle budding and fusion. The half-a-century concept and studies that attribute vesicle-coat contents’ function to Ω-profile formation and classify budding as coat-protein (e.g., clathrin)-dependent or -independent may need to be re-defined and re-examined by considering clathrin’s pivotal role in pore constriction/closure.

Conditional disruption of Nr5a1 directed by Sox9-Cre impairs adrenal development

The current study aimed to investigate the effect of Sox9-Cre-directed Nr5a1-conditional knockout (Sox9-Cre;Nr5a1flox/flox) on adrenal development. We showed that SOX9 is expressed by adrenocortical cells at E10.5–E11.5 but is extinguished no later than E12.5. The number of adrenocortical cells significantly reduced in Sox9-Cre;Nr5a1flox/flox mice while the number of cleaved caspase 3-positive cells increased compared to that in the controls at E11.5–E12.5, when the adrenal primordium (AP) is about to expand. This indicated that fetal adrenocortical cells are lost via apoptosis due to Nr5a1 ablation by E12.5. Both medulla formation and encapsulation were perturbed, accompanied by a smaller AP size, in Sox9-Cre;Nr5a1flox/flox mice during embryonic development. Adult Sox9-Cre;Nr5a1flox/flox adrenals were hypoplastic and exhibited irregular organization of the medulla with aberrant sex differentiation in the X zone. Additionally, there were histologically eosin-negative vacuolated cells, which were negative for both the X-zone marker 20αHSD and the steroidogenesis marker 3βHSD at the innermost cortex of Sox9-Cre;Nr5a1flox/flox adrenals. Although Nr5a1+/− adrenals were hypoplastic, a small number of chromaffin cells were properly located in the center, having normal sex differences in the X-zone. The results collectively provided in-vivo evidence that Nr5a1 plays a critical role in AP expansion and subsequent adrenal development.

Evaluation of pharmacokinetics, safety, and efficacy of [211At] meta-astatobenzylguanidine ([211At] MABG) in patients with pheochromocytoma or paraganglioma (PPGL): A study protocol.

Pheochromocytoma, or paraganglioma (PPGL), is a tumor that arises from catecholamine-producing chromaffin cells of the adrenal medulla or paraganglion. Systemic therapy, such as the combination of cyclophosphamide, vincristine, and dacarbazine or therapeutic radiopharmaceuticals such as [131I] meta-iodobenzylguanidine (MIBG), may be administered in cases of locally advanced tumors or distant metastases. However, the current therapies are limited in terms of efficacy and implementation. [211At] meta-astatobenzylguanidine (MABG) is an alpha-emitting radionuclide-labeled ligand that has demonstrated remarkable tumor-reducing effects in preclinical studies, and is expected to have a high therapeutic effect on pheochromocytoma cells. We are currently conducting an investigator-initiated first-in-human clinical trial to evaluate the pharmacokinetics, safety, and efficacy of [211At] MABG. Patients with locally unresectable or metastatic PPGL refractory to standard therapy and scintigraphically positive [123I] MIBG aggregation are being recruited, and a 3 + 3 dose escalation design was adopted. The initial dose of [211At] MABG is 0.65 MBq/kg, with a dose escalation in a 1:2:4 ratio in each cohort. Dose-limiting toxicity is observed for 6 weeks after a single bolus dose of [211At] MABG, and the patients are observed for 3 months to explore safety and efficacy profiles. The primary endpoint is dose-limiting toxicity to determine both maximum tolerated and recommended doses. The secondary endpoints include radiopharmacokinetics, urinary radioactive excretion rate, urinary catecholamine response rate, objective response rate, progression free survival, [123I] MIBG scintigraphy on reducing tumor accumulation, and quality of life. jRCT2021220012 registered on 17 June 2022.

AMPK inhibits voltage-gated calcium channel-current in rat chromaffin cells

Metabolic changes are critical in the regulation of Ca2+ influx in central and peripheral neuroendocrine cells. To study the regulation of L-type Ca2+ channels by AMPK we used biochemical reagents and ATP/glucose-concentration manipulations in rat chromaffin cells. AICAR and Compound-C, at low concentration, significantly induce changes in L-type Ca2+ channel-current amplitude and voltage dependence. Remarkably, an overlasting decrease in the channel-current density can be induced by lowering the intracellular level of ATP. Accordingly, Ca2+ channel-current density gradually diminishes by decreasing the extracellular glucose concentration. By using immunofluorescence, a decrease in the expression of CaV1.2 is observed while decreasing extracellular glucose, suggesting that AMPK reduces the number of functional Ca2+ channels into the plasma membrane. Together, these results support for the first time the dependence of metabolic changes in the maintenance of Ca2+ channel-current by AMPK. They reveal a key step in Ca2+ influx in secretory cells.

A comparative analysis of surgically excised hereditary and sporadic pheochromocytomas: Insights from a single-center experience.

Pheochromocytoma is a tumor that usually originating from adrenal medullary chromaffin cells and producing one or more catecholamines, can manifest as hereditary or sporadic. While the majority pheochromocytomas are sporadic, hereditary forms are often associated with genetic syndromes such as von Hippel-Lindau, multiple endocrine neoplasia type 2, and neurofibromatosis type 1. This study aims to analyze data from our series of surgically excited pheochromocytoma patients and compare the characteristics between hereditary and sporadic cases. We retrospectively evaluated 33 diagnosed pheochromocytoma patients, documenting clinical features, surgical complications, and tumor characteristics in both hereditary and sporadic cases. Among the patients, 21% (7 individuals) had hereditary pheochromocytoma, while 79% (26 individuals) had sporadic cases. During diagnosis, hereditary pheochromocytoma patients exhibited a significantly lower mean age compared to the sporadic group (26.4 ± 9.9 years vs. 50.4 ± 14.0 years; p < 0.001). The maximum tumor size was also lower in hereditary cases compared to sporadic cases (p = 0.004). Adrenal tumor localization analysis showed that 63.6% were right-sided, 24.2% were left-sided, and 12.1% were bilateral. Laboratory analysis revealed significantly higher urinary norepinephrine levels in hereditary pheochromocytoma patients (p = 0.021). Our findings suggest that hereditary pheochromocytoma cases are characterized by a younger age at diagnosis, smaller tumor size, and a higher prevalence of multiple bilateral adrenal adenomas. We recommend genetic testing for all pheochromocytoma patients, particularly those with early-onset disease and bilateral adrenal tumors.

Cardiac repolarization abnormalities and neurally mediated syncope: overlooked aspects in the diagnosis of pheochromocytoma

BackgroundPheochromocytoma is a rare catecholamine-producing tumour originating from adrenal chromaffin cells. Classic clinical presentation includes headache, diaphoresis and palpitation. Syncope is uncommon and may result from hypotension or arrhythmia. We report a case of neurally mediated syncope in pheochromocytoma associated with cardiac repolarization abnormalities, a unique presentation of the disease.Case presentationThis case report presents a 28 year-old woman, describing recurrent syncope usually preceded by prodromes such as headache, visual blurring, heart palpitations and psychomotor agitation. Firstly she was diagnosed with anxiety and depression, but there was no improvement of symptoms with psychiatric treatment. Previous Holter revealed long QT interval. Echocardiogram showed normal dimensions, preserved left ventricular function and no valvopathies. The patient was referred for a Head-up tilt test (HUTT) in order to investigate reflex syncope. The electrocardiogram (ECG) exhibited normal sinus rhythm and diffuse cardiac repolarisation abnormalities. HUTT was positive for vasodepressor type neurally mediated syncope and ECG showed U waves after a syncope episode. This electrocardiographic finding motivated further clinical investigation. The patient also described abdominal pain, increased abdominal volume, weight loss and blood pressure instability. Based on clinical history and ventricular repolarisation abnormalities uncovered by HUTT, pheochromocytoma was suspected. Urinary test was positive for catecholamines and the abdominal imaging revelead expansive lesion. She underwent surgery to remove the pheochromocytoma, confirmed by immunohistochemistry.ConclusionsAfter surgery she had no recurrency of symptoms, remaining asymptomatic after six years of follow-up, suggesting a cause-effect relationship between neurally mediated syncope and pheochromocytoma.