Chromaffin Cells Of Adrenal Medulla Research Articles

Postnatal Exposure to the Endocrine Disruptor Dichlorodiphenyltrichloroethane Affects Adrenomedullary Chromaffin Cell Physiology and Alters the Balance of Mechanisms Underlying Cell Renewal.

Dichlorodiphenyltrichloroethane (DDT) is a wide-spread systemic pollutant with endocrine disrupting properties. Prenatal exposure to low doses of DDT has been shown to affect adrenal medulla growth and function. The role of postnatal exposure to DDT in developmental disorders remains unclear. The aim of the present investigation is to assess growth parameters and the expression of factors mediating the function and renewal of chromaffin cells in the adult adrenal medulla of male Wistar rats exposed to the endocrine disruptor o,p'-DDT since birth until sexual maturation. The DDT-exposed rats exhibited normal growth of the adrenal medulla but significantly decreased tyrosine hydroxylase production by chromaffin cells during postnatal period. Unlike the control, the exposed rats showed enhanced proliferation and reduced expression of nuclear β-catenin, transcription factor Oct4, and ligand of Sonic hedgehog after termination of the adrenal growth period. No expression of pluripotency marker Sox2 and absence of Ascl 1-positive progenitors were found in the adrenal medulla during postnatal ontogeny of the exposed and the control rats. The present findings indicate that an increase in proliferative activity and inhibition of the formation of reserve for chromaffin cell renewal, two main mechanisms for cell maintenance in adrenal medulla, in the adult DDT-exposed rats may reflect a compensatory reaction aimed at the restoration of catecholamine production levels. The increased proliferation of chromaffin cells in adults suggests excessive growth of the adrenal medulla. Thus, postnatal exposure to DDT alters cell physiology and increases the risk of functional insufficiency and hyperplasia of the adrenal medulla.

The effects of perioperative dexmedetomidine infusion on hemodynamic stability during laparoscopic adrenalectomy for pheochromocytoma: a randomized study.

Pheochromocytoma is a rare catecholamine-producing neuroendocrine tumor originating from the adrenal medulla chromaffin cells. Hemodynamic instability can occur during the induction of anesthesia and surgical manipulation of the tumor. This study investigated the effects of intraoperative dexmedetomidine administration on hemodynamic stability in patients undergoing laparoscopic adrenalectomy for pheochromocytoma. Forty patients who underwent laparoscopic adrenalectomy for pheochromocytoma were randomly assigned to the dexmedetomidine (n = 20) or control (n = 20) group. The primary outcome of this study was intraoperative hemodynamic stability, and the secondary endpoint was the plasma catecholamine concentrations, specifically of epinephrine and norepinephrine. The intraoperative maximum blood pressures were significantly lower in the dexmedetomidine group (control vs. dexmedetomidine group: 182 ± 31 vs. 161 ± 20, 102 ± 17 vs. 90 ± 10, and 128 ± 22 vs. 116 ± 12 [mean ± SD] mmHg and p = 0.020, 0.015, and 0.040 for systolic, diastolic, and mean blood pressure, respectively). The maximum heart rate during surgery was 108 ± 15 bpm in the control group and 95 ± 12 bpm in the dexmedetomidine group (p = 0.010). Other parameters of hemodynamic instability were comparable between both groups. Plasma catecholamine concentrations did not differ between the groups. Dexmedetomidine infusion following the induction of anesthesia at a rate of 0.5 μg/kg/h significantly attenuated the maximum intraoperative SBP, DBP, MBP, and HR, contributing to improved hemodynamic stability.

FRI208 Treating Pheochromocytoma For Glycemic And Blood Pressure Control

Abstract Disclosure: A.M. Santiago Carrion: None. A.N. Gonzalez Bossolo: None. Pheochromocytomas are catecholamine-secreting tumors of the adrenal medulla chromaffin cells. They account for 0.2-0.6% of hypertension (HTN) in patients of general outpatient clinics. In addition, is known that this excess of catecholamine production is associated with impaired insulin release from pancreatic beta-cells leading to hyperglycemia. However, pheochromocytoma as a cause of diabetes and HTN is frequently overlooked. A 60-year-old woman with medical history of arterial HTN and type 2 diabetes mellitus since 10 years ago was referred to the Endocrine clinic by Nephrology for glycemic control. Her medical regimen consisted of linagliptin 5mg daily, metformin 1000mg twice daily, insulin glargine 40 units daily, losartan 50mg twice daily, amlodipine 10mg daily and hydrochlorothiazide 25mg daily. Physical examination was unremarkable, including adequate vital signs with blood pressure 110/64 mmHg and heart rate 93/min. Laboratories were notable for glycated hemoglobin 8.7%, fasting blood glucose 118 mg/dL, and urine albumin-creatinine ratio (UACR) 4622 mg/g with adequate glomerular filtration rate. Upon further investigation of nephrotic-range proteinuria, patient was incidentally found with a right adrenal mass on ultrasound, which was confirmed to have absent signal dropout on MRI and measured 5 cm. On retrospective, patient revealed feeling episodic palpitations, diaphoresis, and occasional headaches which she attributed to menopausal symptoms. Plasma free metanephrines were negative, but free normetanephrines were elevated at 2160 pg/mL (range <148 pg/mL). Patient underwent successful right adrenalectomy and pathology confirmed a right 5 cm pheochromocytoma with negative margins. Unfortunately, she wished to defer genetic testing. Four weeks after surgery, plasma normetanephrines fell to normal levels 141.8 pg/mL. Furthermore, patient was able to wean off basal insulin completely and HTN remained controlled with losartan monotherapy. Glycated hemoglobin improved to 6.7%. Additionally, UACR improved to 1352.94 mg/g and empagliflozin was added to avoid diabetic kidney progression. In this case we presented a patient with common comorbidities encountered in the clinic, but with an unusual etiology. Moreover, this patient presented with nephrotic-range proteinuria that has significantly improved after removal of the tumor, which has only been seen in case reports. Some authors propose a possible immunological pathogenesis or glomerular hyperfiltration. Detection of resistant HTN should had prompted earlier detection of pheochromocytoma in this patient. As physicians, we should be aware of endocrine causes of diabetes and HTN, such as Cushing syndrome, Acromegaly, Primary Aldosteronism, and Pheochromocytoma and Paraganglioma, as treating these may lead to better quality of life, and less disease-related complications and polypharmacy. Presentation: Friday, June 16, 2023

Biochemical analysis and management of phaeochromocytoma: A case report

Phaeochromocytoma is a tumour from chromaffin cells in adrenal medulla or extra-adrenal autonomic ganglia, usually releasing catecholamines and metanephrines. It is an unusual cause of severe hypertension in the young. This is the first report from our hospital, the Federal Medical Centre, Umuahia. There are important steps in management which if unattended to results in high peri-operative mortality. This article highlight these issues in its management.

MASH1 induces neuron transdifferentiation of adrenal medulla chromaffin cells.

Nerve growth factor (NGF) induces neuron transdifferentiation of adrenal medulla chromaffin cells (AMCCs) and consequently downregulates the secretion of epinephrine (EPI), which may be involved in the pathogenesis of bronchial asthma. Mammalian achaete scute-homologous 1 (MASH1), a key regulator of neurogenesis in the nervous system, has been proved to be elevated in AMCCs with neuron transdifferentiation in vivo. This study aims to explore the role of MASH1 in the process of neuron transdifferentiation of AMCCs and the mechanisms. Rat AMCCs were isolated and cultured. AMCCs were transfected with siMASH1 or MASH1 overexpression plasmid, then were stimulated with NGF and/or dexamethasone, PD98059 (a MAPK kinase-1 inhibitor) for 48 hours. Morphological changes were observed using light and electron microscope. Phenylethanolamine-N-methyltransferase (PNMT, the key enzyme for epinephrine synthesis) and tyrosine hydroxylase were detected by immunofluorescence. Western blotting was used to test the protein levels of PNMT, MASH1, peripherin (neuronal markers), extracellular regulated protein kinases (ERK), phosphorylated extracellular regulated protein kinases (pERK), and JMJD3. Real-time RT-PCR was applied to analyze the mRNA levels of MASH1 and JMJD3. EPI levels in the cellular supernatant were measured using ELISA. Cells with both tyrosine hydroxylase and PNMT positive by immunofluorescence were proved to be AMCCs. Exposure to NGF, AMCCs exhibited neurite-like processes concomitant with increases in pERK/ERK, peripherin, and MASH1 levels (all P<0.05). Additionally, impairment of endocrine phenotype was proved by a signifcant decrease in the PNMT level and the secretion of EPI from AMCCs (all P<0.01). MASH1 interference reversed the effect of NGF, causing increases in the levels of PNMT and EPI, conversely reduced the peripherin level and cell processes (all P<0.01). MASH1 overexpression significantly increased the number of cell processes and peripherin level, while decreased the levels of PNMT and EPI (all P<0.01). Compared with the NGF group, the levels of MASH1, JMJD3 protein and mRNA in AMCCs in the NGF+PD98059 group were decreased (all P<0.05). After treatment with PD98059 and dexamethasone, the effect of NGF on promoting the transdifferentiation of AMCCs was inhibited, and the number of cell processes and EPI levels were decreased (both P<0.05). In addition, the activity of the pERK/MASH1 pathway activated by NGF was also inhibited. MASH1 is the key factor in neuron transdifferentiation of AMCCs. NGF-induced neuron transdifferentiation is probably mediated via pERK/MASH1 signaling.

María Teresa Miras Portugal: a pioneer for vesicular nucleotide storage.

Chromaffin granules are secretory granules present in adrenal medulla chromaffin cells. They contain high contents of catecholamines and nucleotides and have been regarded as a model system for the study of vesicular transmitter uptake and release. In 1988, Dr. María Teresa Miras Portugal, when studying catecholamine biosynthesis, detected a novel group of nucleotides, the diadenosine polyphosphates, in the adrenal chromaffin granules. Based on this finding, she unraveled the existence of diadenosine polyphosphate-mediated chemical transmission, leading to a paradigm shift in the field of purinergic signaling. She is also a pioneer in the studies on vesicular nucleotide storage. First, María Teresa and her group characterized nucleotide transport in chromaffin granules and synaptic vesicles using fluorescent nucleotide derivatives such as 1, N6-ethenoadenosine triphosphates. Then, they revealed the presence of a hypothetical vesicular nucleotide transporter with unique properties in terms of substrate specificity. In this article, we will describe her contributions to vesicular nucleotide storage and the foundations she laid for future studies.

Deep Membrane Proteome Profiling Reveals Overexpression of Prostate-Specific Membrane Antigen (PSMA) in High-Risk Human Paraganglioma and Pheochromocytoma, Suggesting New Theranostic Opportunity.

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors arising from chromaffin cells of adrenal medulla or sympathetic or parasympathetic paraganglia, respectively. To identify new therapeutic targets, we performed a detailed membrane-focused proteomic analysis of five human paraganglioma (PGL) samples. Using the Pitchfork strategy, which combines specific enrichments of glycopeptides, hydrophobic transmembrane segments, and non-glycosylated extra-membrane peptides, we identified over 1800 integral membrane proteins (IMPs). We found 45 “tumor enriched” proteins, i.e., proteins identified in all five PGLs but not found in control chromaffin tissue. Among them, 18 IMPs were predicted to be localized on the cell surface, a preferred drug targeting site, including prostate-specific membrane antigen (PSMA), a well-established target for nuclear imaging and therapy of advanced prostate cancer. Using specific antibodies, we verified PSMA expression in 22 well-characterized human PPGL samples. Compared to control chromaffin tissue, PSMA was markedly overexpressed in high-risk PPGLs belonging to the established Cluster 1, which is characterized by worse clinical outcomes, pseudohypoxia, multiplicity, recurrence, and metastasis, specifically including SDHB, VHL, and EPAS1 mutations. Using immunohistochemistry, we localized PSMA expression to tumor vasculature. Our study provides the first direct evidence of PSMA overexpression in PPGLs which could translate to therapeutic and diagnostic applications of anti-PSMA radio-conjugates in high-risk PPGLs.

Antiproliferative effects of metformin in cellular models of pheochromocytoma

Pheochromocytomas (PCCs) are rare neuroendocrine tumors derived from adrenal medulla chromaffin cells. Malignancy and recurrence are rare but demand effective treatment. Metformin exerts antiproliferative effects in several cancer cell lines. We thus evaluated the effects of metformin on cell viability and proliferation, cellular respiration and AMPK-AKT-mTOR-HIFA proliferation pathway on a rat PCC cell line (PC12-Adh). We then addressed metformin's effects on the AMPK-AKT-mTOR-HIFA pathway on two human primary cultures: one from a VHL-mutant PCC and other from a sporadic PCC. Metformin (20 mM) inhibited PC12-Adh cell proliferation, and decreased oxygen consumption, ATP production and proton leak, in addition to loss of mitochondrial membrane potential. Further, metformin induced AMPK phosphorylation and impaired AMPK-PI3k-AKT-mTOR pathway activation. The mTOR pathway was also inhibited in human VHL-related PCC cells, however, in an AMPK-independent manner. Metformin-induced decrease of HIF1A levels was likely mediated by proteasomal degradation. Altogether our results suggest that metformin impairs PCC cellular proliferation.

The abnormalities of adrenomedullary hormonal system in genetic hypertension: Their contribution to altered regulation of blood pressure.

It is widely accepted that sympathetic nervous system plays a crucial role in the development of hypertension. On the other hand, the role of adrenal medulla (the adrenomedullary component of the sympathoadrenal system) in the development and maintenance of high blood pressure in man as well as in experimental models of hypertension is still controversial. Spontaneously hypertensive rats (SHR) are the most widely used animal model of human essential hypertension characterized by sympathetic hyperactivity. However, the persistence of moderately elevated blood pressure in SHR subjected to sympathectomy neonatally as well as the resistance of adult SHR to the treatment by sympatholytic drugs suggests that other factors (including enhanced activity of the adrenomedullary hormonal system) are involved in the pathogenesis of hypertension of SHR. This review describes abnormalities in adrenomedullary hormonal system of SHR rats starting with the hyperactivity of brain centers regulating sympathetic outflow, through the exaggerated activation of sympathoadrenal preganglionic neurons, to the local changes in chromaffin cells of adrenal medulla. All the above alterations might contribute to the enhanced release of epinephrine and/or norepinephrine from adrenal medulla. Special attention is paid to the alterations in the expression of genes involved in catecholamine biosynthesis, storage, release, reuptake, degradation and adrenergic receptors in chromaffin cells of SHR. The contribution of the adrenomedullary hormonal system to the development and maintenance of hypertension as well as its importance during stressful conditions is also discussed.

Detection of Biomolecules by HPLC-EC

Peptides which are biologically active are attracting remarkable interest due to its influence in different areas such as pathophysiological and psychiatric disorders. Neuropeptide Y (NPY) is a 36 amino acid amidated neuropeptide that occurs in both the central nervous system and peripheral tissues. This neuropeptide is known because its different levels have been reported affect different processes such as stress-related disorders, major depressive disorders and ingestive behavior. NPY is a neurotransmitter produced by chromaffin cells of adrenal medulla, it acts through different G protein-coupled receptors ( Y1 Y2 Y 3 Y 4 Y5) and its important because it stimulated catecholamines release.Catecholamines are nerve-endogenous substances with amine and catechol groups such as epinephrine, norepinephrine and dopamine. These molecules also play an important role in the regulation of the central and peripheral nervous system and they are mostly used to diagnose and treat several diseases. The importance of this project lies on the use of High-Performance Liquid Chromatography couple with Electrochemical Impedance Spectroscopy for catecholamines detection. This techniques allow researchers to detect these biomolecules more accurately in time and space. For a better understanding of the catecholamines release we use HPLC-EC. This is a method with high sensitivity which has been used during years for the characterization of different biomolecules. Our HPLC have a electrochemical detector (HPLC-EC) which improves the sensitivity and the resolution of our analysis. We decided to make our analysis by Size Exclusion using 1X PBS.

Anaesthetic Management for Laparascopic Adrenalectomy for Pheochromocytoma as Part of Vonn Hippel-Lindau Syndrome in Child

Pheochromocytoma is a tumor that originates from either chromaffincells in adrenal medulla or in other paraganglia tissues (paragangliomas) of the sympathetic nervous system. It might be familial and associated with hereditary tumors such as Von Hippel-Lindau syndrome and multiple endocrine neoplasia type II. The symptoms are variable related to the level of secreted catecholamine. The most common are hypertension, tachycardia, headache and abdominal pain. The most effective treatment is surgical resection as in recent years, laparoscopic surgery has been more preferred. The perioperative management is quite challenging especially in view of hemodynamic fluctuations. Although there is a considerable amount of information on the management of the adult with phaeochromocytoma, much less has been written concerning children with the disease. We present a case of 9-year-old hypertensive boy with left sided pheochromocytoma, scheduled for excision of tumour. He had presented with complaints of pain in abdomen, excessive sweating, headache and raised blood pressure, as well as family anamnesis for von Hippel-Lindau syndrome (father with confirmed diagnosis). Diagnosis was confirmed by CT scan (abdomen), raised 24-hour urinary catecholamine levels and genetics tests. Preoperative blood pressure was controlled with prazosin (ά-adrenergic blocker). The anaesthetic technique used was general anaesthesia. Child was later discharged on oral antihypertensive.

Incidental Pheochromocytoma: Silent but Violent

Background: Pheochromocytoma is a rare catecholamine secreting neuroendocrine tumor. It arises from the chromaffin cells of adrenal medulla. It is diagnosed in 5–6.5% of adrenal incidentalomas which is not common. The usual clinical presentation includes the classic triad of sweating, headache and tachycardia. However, asymptomatic cases are seen in 8% of the patients with pheochromocytoma. We present a clinically asymptomatic patient diagnosed during work up of adrenal incidentaloma. The possible etiology for silent presentation includes one of the following:(i) Presence of a smaller functional tissue (ii)Accelerated turnover of the tumor causing release of the unmetabolized catecholamines in small amounts (iii) Pulsatile tumor secretion (iv)Tumors triggered by stress (v) Laboratory errors due to inappropriate handling of specimen at high-temperature (vi) False negative test results secondary to caffeine ingestion in the prior 24 hours.Clinical Case: 59 years old Caucasian female with past medical history of type 2 diabetes mellitus, obesity, essential hypertension, nonischemic cardiomyopathy, and asthma presented to the emergency room with complaints of worsening shortness of breath and pedal edema for 1 month. Physical exam: Blood pressure 146/78 mm of Hg and heart rate 82 beats/min, mild pedal edema, no pulmonary crackles. On imaging, CT angio chest showed irregularly enhancing right adrenal mass measuring 3.4 cm. This adrenal incidentaloma was not visualized on imaging done 5 years ago. Further, MRI abdomen revealed 4.1 cm right adrenal mass. Laboratory testing showed high total plasmametanephrines: 890 pg/ml (< or = 205), 24-hour urine metanephrines: 2337 (140–785), A1C: 10%. This confirmed the diagnosis of adrenal pheochromocytoma. Preoperatively, she was started on phenoxybenzamine 10 mg BID and encouraged on liberal salt intake. During the course, her blood pressure and heart rate were monitored daily. She underwent right adrenalectomy. Surgical pathology revealed 4.1 cm pheochromocytoma, negative margins with extension to the adipose tissues and vascular invasion, PASS score = 4. Post operatively, patient declined to get labs done. Due to high risk behavior of the tumor, patient needs to be monitored annually for lifelong.Conclusion: Pheochromocytoma is an uncommon tumor with varied clinical presentation. It can manifest itself widely from being silent to aggressive disease. This warrants high suspicion, early detection and management, thereby reducing the morbidity and mortality. Lately, there has been increased incidence of adrenal incidentalomas owing to widespread use of radiological investigations. We report a case of incidental pheochromocytoma which is biochemically active but clinically asymptomatic. This emphasizes the importance of being more vigilant during the evaluation of adrenal incidentalomas.

The Effects of Acute Glucoprivation on Adrenomedullary Function in SHR and WKY Rats

We have shown previously, acute intraperitoneal administration of 2-deoxy-d-glucose (2DG) into Sprague-Dawley rats led to activation of the adrenal medulla chromaffin cells, indicated with increased protein kinase activity and increased tyrosine hydroxylase (TH) phosphorylation, as well as increased plasma adrenaline and glucose levels. Here we have used spontaneous hypertensive (SHR) and Wistar Kyoto (WKY) rats to investigate whether hypertension alters basal adrenal chromaffin cell function, or the response of these cells to acute 2DG treatment. At basal level, we found no differences in adrenal medulla TH protein, TH phosphorylation, TH activity or catecholamine levels between SHR and WKY despite a significant difference in the level of systolic blood pressure; nor were there differences in plasma catecholamine levels or blood glucose (BG). Furthermore, the vehicle animals evoked no significant changes in any parameter measured in SHR, but evoked significant increases in pSer19TH, plasma adrenaline and BG in WKY. Single episode of glucoprivation evoked increases in PKA and CDK/MAPK, pSer40TH, pSer31TH, TH activity, and plasma adrenaline and BG in SHR, and in addition evoked increases in PKC, CAMKII, and pSer19TH in WKY. These findings are significant which indicates hypertension does not impact catecholamine function in the adrenal gland. It also appears that hypertension does not alter the adrenal response to glucoprivation. The findings are also significant as WKY showed greater adrenal activation of protein kinases and TH phosphorylation in response to saline and 2DG when compared to SHR and possible reasons for these findings are further discussed.

An unusual and interesting case of phaeochromocytoma

Phaeochromocytomas are catecholamine-secreting tumours that arise from chromaffin cells of the adrenal medulla. The common age of onset is between the third and fifth decades of life. Commonly adrenal phaeochromocytoma secretes epinephrine (its metabolite metanephrine). Extra-adrenal phaeochromocytoma secretes norepinephrine and normetanephrine. Herein, we present the case of a 13-year-old male patient who presented with palpitations, giddiness and increased appetite for 3 days. He was found to have de novo hypertension. Imaging showed bilateral adrenal masses. Biochemical analysis revealed normal levels of plasma and 24-h urinary metanephrines. On further evaluation, serum metanephrine-fractionated assay showed marked elevation in normetanephrine levels. The patient was initially managed medically with alpha- and beta-blockers. After controlling blood pressure, adrenalectomy was done. The histopathological examination was suggestive of phaeochromocytoma. Adrenal phaeochromocytoma-secreting normetanephrines are a rare entity. On reviewing literature, only a few cases of this type were published.

Abstract 5973: GIPC2 is a candidate tumor suppressor gene in sporadic pheochromocytoma

Abstract Pheochromocytoma (PCC) is a rare endocrine tumor of the chromaffin cells in adrenal medulla or the paraganglia. Currently about 60% of PCCs can be explained by germline or somatic mutations in well-established susceptibility genes such as RET, VHL and SDHB, while for the remaining, mainly sporadic cases the pathogenesis is still unclear. We explored the molecular basis of these PCCs by analyzing 22 sporadic adrenal PCCs, using SNP6.0 arrays to identify minimal region of the most common chromosomal loss, and expression profiling to identify genes with suppressed expression relative to normal medulla. Here we report the identification of GIPC2, a gene located at 1p31.1 encoding a PDZ domain containing adaptor protein with preferential expression in adrenal, as a putative tumor suppressor gene for sporadic PCC. In a cohort of 55 sporadic PCCs, 38 were found with reduced genomic copy number of GIPC2, with accompanying reduced expression of mRNA. Much reduced or loss of GIPC2 protein expression in tumor tissues was confirmed with Western blot or immunostaining. No GIPC2 mutations were found in the cohort but significant promoter hypermethylation was demonstrated using MassARRAY EpiTYPER assay and methylation-specific PCR. The GIPC2 protein was expressed mostly in the nucleus. With GIPC2 overexpression or siRNA knockdown in both PCC derived cell lines (rat PC12 or hPheo, a cell line derived from human PCC) and primary rat adrenal chromaffin cells (ACC), we showed that GIPC2 suppressed cell proliferation by inducing cyclin kinases such as p27, and by suppressing the activation of MAPK/Erk pathways without affecting pAKT or mTOR pathways. PC12 cells stably overexpressing GIPC2 failed to develop tumor in nude mice. To explore the molecular mechanism of GIPC2 in cell cycle regulation, we searched for its interaction proteins in 293T cells via mass spectrometry and identified NONO, a nucleoprotein with a known role in regulating cell cycle. Reciprocal interaction between GIPC2 and NONO was demonstration in PC12 or hPheo cells in vivo using immune-IP or FRET. We showed that knockdown of NONO blocked GIPC2-mediated p27 up-regulation. Furthermore both GIPC2 and NONO regulated p27 promoter through the same DNA binding site and a GGCC box was significant for GIPC2-regulated p27 promoter activity through NONO. Finally, we found that PCC-causing mutations in RET and SDHB, but not VHL, genes could lead to ACC proliferation and p27 downregulation via down-regulating GIPC2. In summary, our study indicates that GIPC2 acts as a candidate tumor suppressor gene in sporadic pheochromocytomas and regulates cell cycle gene p27 through NONO. Our results provide a new insight into the molecular mechanism of sporadic PCCs. Citation Format: Yeqing Dong, Zhengguang Guo, Chengyan Fan, Zhi Zheng. GIPC2 is a candidate tumor suppressor gene in sporadic pheochromocytoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5973.

Zamicastat is a noncompetitive Dopamine‐β‐hydroxylase inhibitor that modulates sympathetic nervous system activity

Dopamine‐β‐hydroxylase (DβH; EC 1.14.17.1) is an enzyme responsible for the conversion of dopamine (DA) into norepinephrine (NE). It is present in the chromaffin cells of adrenal medulla and in noradrenergic nerve terminals of the central and peripheral sympathetic nervous system. DβH inhibition has been proposed as an alternative mechanism for the treatment of hypertension and chronic heart failure. Zamicastat ((R)‐5‐(2‐(benzylamino)ethyl)‐1‐(6,8‐difluorochroman‐3‐yl)‐1H‐imidazole‐2(3H)‐thione) is a novel DβH inhibitor. The aim of this study was to characterize the pharmacodynamics of Zamicastat in vivo, both in Wistar Han and in spontaneously hypertensive rats (SHR), and on DβH in human cells. DβH activity was measured by a modification of the Nagatsu and Udenfriend (1) spectrophotometric method, based on the conversion of tyramine into octopamine either in adrenal tissues of rats administered orally with Zamicastat (30 mg/Kg) or vehicle, or in human neuroblastoma (SK‐N‐SH) cells. Zamicastat pharmacodynamic characterization in vivo was performed in Wistar rats by evaluating NE and DA levels in tissues using HPLC with electrochemical detection at 9h post‐administration. Additionally, systolic and diastolic blood pressure, heart rate and activity were measured continually by telemetry in SHR rats (a model of essential hypertension) and their controls, Wistar Kyoto (WKY). Zamicastat was found to be a reversible noncompetitive inhibitor of DβH towards tyramine, with a Ki value of 43 (21; 66) nM and either noncompetitive or uncompetitive towards ascorbic acid. Zamicastat (30 mg/Kg, p.o.) fully inhibits adrenal DβH activity from 2 to 8h recovering to baseline values after 24h. This is accompanied with a decrease in NE and an increase in DA in peripheral tissues, namely left ventricle and kidney but not significantly in the central nervous system (brain stem or prefrontal‐cortex). Zamicastat at 3, 30 and 100 mg/Kg displayed a dose‐dependent decrease on systolic and diastolic blood pressure with no effect in heart rate or overall activity when evaluated in SHR rats by telemetry. In conclusion, Zamicastat is a DβH inhibitor displaying binding affinity for both the free enzyme and the complex enzyme‐substrate, that when orally administered at 30 mg/Kg to rats acts peripherally and significantly reduces sympathetic activity by decreasing NE levels and consequently systolic and diastolic blood pressure in an animal model of essential hypertension.

Pheochromocytoma: A Clinicopathologic Case Series

Introduction: Pheochromocytoma is a rare neuroendocrine tumor derived from the chromaffin cells of adrenal medulla. The incidence ranges from 0.005% to 0.1% in the general population.Case Presentation: This case series reported 4 patients with pheochromocytoma who were diagnosed at Sanglah General Hospital Denpasar over a period of three years (2017–2019). The age ranged from 15–59 years with the mean age of 41 + 18.9 years. A similar proportion was found for both sexes. Clinical features include lumps, headaches, flank region pain, palpitations and cold sweat. Hypertension was found in 3 cases. Local examination revealed the solid mass in the flank region in all cases; enlarged lymph nodes were found in one case, namely in the paraaortic region. Abdominal MSCT examination findings showed: a solid mass with cystic components in suprarenal; sizes ranging from 1.9 x 2.6 x 2.2 cm to 21.6 x 14.3 x 17.8 cm; bilateral (1 case), unilateral (3 cases); contrast enhancement and hypervascularization, without calcification (4 cases); central necrotic (1 case). All patients underwent radical adrenalectomy. Microscopic features showed the tumor mass which consisted of the proliferation of chromaffin cells forming alveolar (Zellballen) and solid nest patterns separated by capillary blood vessels. The cells were polygonal-shaped with clear cytoplasm, round-shaped nucleus, and moderate pleomorphic. Mitosis was not found. These histomorphologic findings supported the diagnosis of pheochromocytoma.Conclusions: Diagnosis and optimal treatment plans can be established through rapid and precise recognition of pheochromocytoma in order to achieve better outcomes.

Intricacies of the Molecular Machinery of Catecholamine Biosynthesis and Secretion by Chromaffin Cells of the Normal Adrenal Medulla and in Pheochromocytoma and Paraganglioma.

The adrenal medulla is composed predominantly of chromaffin cells producing and secreting the catecholamines dopamine, norepinephrine, and epinephrine. Catecholamine biosynthesis and secretion is a complex and tightly controlled physiologic process. The pathways involved have been extensively studied, and various elements of the underlying molecular machinery have been identified. In this review, we provide a detailed description of the route from stimulus to secretion of catecholamines by the normal adrenal chromaffin cell compared to chromaffin tumor cells in pheochromocytomas. Pheochromocytomas are adrenomedullary tumors that are characterized by uncontrolled synthesis and secretion of catecholamines. This uncontrolled secretion can be partly explained by perturbations of the molecular catecholamine secretory machinery in pheochromocytoma cells. Chromaffin cell tumors also include sympathetic paragangliomas originating in sympathetic ganglia. Pheochromocytomas and paragangliomas are usually locally confined tumors, but about 15% do metastasize to distant locations. Histopathological examination currently poorly predicts future biologic behavior, thus long term postoperative follow-up is required. Therefore, there is an unmet need for prognostic biomarkers. Clearer understanding of the cellular mechanisms involved in the secretory characteristics of pheochromocytomas and sympathetic paragangliomas may offer one approach for the discovery of novel prognostic biomarkers for improved therapeutic targeting and monitoring of treatment or disease progression.

Issue Cover (November 2018)

Journal of NeurochemistryVolume 147, Issue 4 Issue CoverFree Access Issue Cover (November 2018) First published: 26 November 2018 https://doi.org/10.1111/jnc.14201 Read the full article: ‘Altered excitability and exocytosis in chromaffin cells from the R6/1 mouse model of Huntington's disease is linked to over-expression of mutated huntingtin’ by C. Martínez-Ramírez, A. M. Baraibar, C. Nanclares, I. Méndez-López, A. Gómez, Ma. P. Muñoz, A. M. G. de Diego, L. Gandía, M. J. Casarejos, A. G. García (J. Neurochem. 2018, vol. 147 (4), pp. 454–476) on doi: 10.1111/jnc.14585 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Front cover: Background: Neurodegenerative diseases are primarily linked to alterations of neurotransmitter release and synaptic plasticity in the brain. However, the peripheral sympatho-adrenal axis has been found to be also altered in some of those diseases. Here we present a study on morphological and functional alterations in adrenal chromaffin cells (CCs) of the R6/1 mouse model of Huntington's disease (HD). Main finding: We have found (i) huntingtin overexpression as nuclear aggregates in CCs; (ii) smaller CC size with decreased dopamine β-hydroxylase expression, indicating lesser number of chromaffin secretory vesicles; (iii) reduced adrenal tissue catecholamine content; (iv) reduced Na+ currents with (v) membrane hyperpolarisation and reduced ACh-evoked action potentials; (v) reduced [Ca2+]c transients with faster Ca2+ clearance; (vi) diminished quantal secretion with smaller vesicle quantal size; (vii) faster kinetics of the exocytotic fusion pore, pore expansion, and closure. Implications: As the sympatho-adrenal axis plays an essential role in adaptation to stress through the fight-or-flight response, this study suggests that such response could be sharply deteriorated in HD patients. Image Content: The image shows an immunohistochemical staining for mutated huntingtin (Htt) in adrenal medulla chromaffin cells of the R6/1 mice at predisease stages (2 months age, 2m) before phenotypic motor alterations appear. Read the full article ‘Altered excitability and exocytosis in chromaffin cells from the R6/1 mouse model of Huntington's disease is linked to over-expression of mutated huntingtin’ by C. Martínez-Ramírez, A. M. Baraibar, C. Nanclares, I. Méndez-López, A. Gómez, Ma. P. Muñoz, A. M. G. de Diego, L. Gandía, M. J. Casarejos, A. G. García (J. Neurochem. 2018, vol. 147 (4), pp. 454–476) on doi: 10.1111/jnc.14585 Volume147, Issue4November 2018 RelatedInformation

131-I MIBG therapy of malignant pheochromocytoma and paraganglioma tumours - a single-centre study.

Pheochromocytomas and paragangliomas are rare tumors deriving from chromaffin cells of adrenal medulla or paraganglia. They are usually benign but 10-35% of them present malignant behavior. The aim of the study was to evaluate the efficacy and safety of 131-I MIBG therapy in malignant pheochromocytoma /paraganglioma patients (MPPGL). 18 patients (7 women and 11 men) were included in this study. Between 2002 and 2016 they underwent 131-I MIBG therapy because of MPPGL and their medical data were analyzed retrospectively. Clinical indications for the treatment included progressive disease or massive tissue involvement independently from disease progression. Tumor response for the first time was assessed 3 months after the last treatment according to Response Evaluation Criteria in Solid Tumors criteria and by 131-I MIBG scans. The mean single dose used was 7.25 GBq (196 mCi) and mean cumulative dose 33.08 GBq ( 894 mCi). In 2 (11%) patients complete tumor response was achieved. In 1 (6%) patient partial response was obtained. In 13 (72%) patients stable disease was observed. In 2 (11%) patients progression was diagnosed three months after treatment discontinuation. In the whole studied group the progression free survival time was 85 months and overall 5-year survival was 87%. Radionuclide treatment with use of 131-I MIBG may be effective form of palliative treatment for patients with inoperative neoplasm spread, progressive disease or patients requiring alleviation of symptoms. < p > < /p >.