Somatotropic Research Articles

Acromegalia em felinos

Acromegaly in felines occurs mainly due to a pituitary adenoma of somatotropic cells, and presents slow and progressive evolution, responsible for increasing the production and secretion of growth hormones (GH). This condition is common in senile or adult male domestic cats, neutered and with short hair. The pathophysiology is due to the excessive release of GH in the adenohypophysis region, whose synthesis is regulated by growth hormone-releasing hormone (GHRH) and somatostatin, responsible for stimulating or inhibiting the secretory axis, respectively. The anabolic action of GH is responsible for increasing the secretion of IGF-1, which is mainly responsible for the clinical signs of acromegaly, such as body growth and organomegaly. The catabolic effect refers to insulin resistance. Clinical signs may be associated with secondary diabetes mellitus (DM), weight gain, exacerbated growth of various tissues and neurological signs as the tumor mass grows. The diagnosis of the disease can be performed through laboratory, imaging and endocrine tests such as the specific immunoassay for GH and/or insulin-like growth factor 1 (IGF-1). Treatment is based on controlling the DM that develops secondary to it, as well as on attempts to reduce or even inhibit the excess release of GH. Treatment can be performed with somatostatin analogues and dopamine agonists. The use of stereotactic radiotherapy can also be recommended, with favorable results for tumor reduction, as well as the surgical technique of transsphenoidal hypophysectomy, which presents better results than other techniques but is a complex surgical procedure. This project aims to inform veterinarians of this endocrine disease and its main currently recognized diagnoses and treatments, emphasizing the need to establish a differential diagnosis for difficult-to-control DM.

8649 Ablation of Leptin Receptors in Somatotropes Impacts Transcriptomic Plasticity in the Pou1f1 Lineage of Female Pituitary Cells

Abstract Disclosure: T.K. Miles: None. A.K. Odle: None. S. Byrum: None. A. Lagasse: None. A. Haney: None. V.G. Ortega: None. A. Herdman: None. M.C. MacNicol: None. A.M. MacNicol: None. G.V. Childs: None. Anterior pituitary somatotropes produce growth hormone (GH) to optimize body composition, receiving tropic signals from leptin about the metabolic state. When leptin receptors are ablated in somatotropes, GH proteins, serum GH and GHRH receptors are reduced. Unexpectedly, POU1F1, Prolactin, and TSH-beta proteins are also reduced in pituitaries of Somatotrope LEPR-null females (mutants), suggesting a tropic role for leptin in differentiation. To test this hypothesis, single cell RNA-seq analysis compared the pituitary transcriptome of 6-month-old control and mutant female mice housed under thermoneutral conditions (28°C). Following scRNA-seq, cells were clustered computationally with the use of Seurat; all cell types were identified in separate UMAP clusters. Mutants showed increases in cell numbers in somatotrope (4.7X) and Pou1f1 (5.7x) clusters, but no change in thyrotrope or lactotrope clusters. In LEPR-null female somatotropes, the 516 differentially expressed genes (DEGs; adj p<0.05) included upregulated Pomc, Prl, Lhb, Tshb and Cga (Log2FC+0.5-1.7) and downregulated Pou1f1, Ghrhr, and Gh (Log2FC -0.5—1.5). In the lactotrope cluster from mutants, Pomc, Cga, and Gh were upregulated (Log2FC+1.1-1.5) and Pou1f1 and Prl were downregulated. The thyrotrope cluster was unchanged. Prl, Pomc, and Gh were upregulated in the Pou1f1 cluster. The down regulation of Gh, Pou1f1, and Ghrhr in somatotropes and Prl in lactotropes correlates with the lower serum levels of GH and Prl in mutant females. However, the upregulated DEGs do not correlate with increased secretory activity suggesting that the multihormonal cells are not fully functional. This was confirmed with Ingenuity Pathway Analysis (IPA) showing downregulation of canonical pathways involved in secretion in mutant somatotropes. Unexpectedly, mutant females exposed to a HFD (60% fat) for 16 weeks (+16.6g) showed a reversal of the changes in somatotrope cell numbers and multihormonal expression seen in control fed mutants. The increase in genes belonging to IPA canonical cytoplasmic translation pathways in mutant somatotropes were also completely reversed following a HFD. Furthermore, the downregulated secretory/signaling pathways seen in control fed mutant female somatotropes and lactotropes (endocytosis, vesicle transport, Gaq, GnRH) were upregulated modestly following a HFD. The high serum leptin in the HFD fed mutant mice may activate signaling pathways in cells still expressing LEPR. Collectively, these results confirm a role for leptin in maintaining differentiated somatotropes. They also suggest that leptin may limit expansion of multihormonal progenitor cells. The decreased multihormonal expression and protein synthesis in lactotrope clusters from mutant mice exposed to a HFD are also seen in lactotropes from control mice on a HFD, which suggests that a HFD may compromise pituitary plasticity. Presentation: 6/3/2024

Paracrine FGF1 signaling directs pituitary architecture and size

Organ architecture is established during development through intricate cell-cell communication mechanisms, yet the specific signals mediating these communications often remain elusive. Here, we used the anterior pituitary gland that harbors different interdigitated hormone-secreting homotypic cell networks to dissect cell-cell communication mechanisms operating during late development. We show that blocking differentiation of corticotrope cells leads to pituitary hypoplasia with a major effect on somatotrope cells that directly contact corticotropes. Gene knockout of the corticotrope-restricted transcription factor Tpit results in fewer somatotropes, with less secretory granules and a loss of cell polarity, resulting in systemic growth retardation. Single-cell transcriptomic analyses identified FGF1 as a corticotrope-specific Tpit dosage-dependent target gene responsible for these phenotypes. Consistently, genetic ablation of FGF1 in mice phenocopies pituitary hypoplasia and growth impairment observed in Tpit-deficient mice. These findings reveal FGF1 produced by the corticotrope cell network as an essential paracrine signaling molecule participating in pituitary architecture and size.

Experimental Autoimmune Encephalomyelitis Influences GH-Axis in Female Rats.

Inflammation, demyelination, and axonal damage to the central nervous system (CNS) are the hallmarks of multiple sclerosis (MS) and its representative animal model, experimental autoimmune encephalomyelitis (EAE). There is scientific evidence for the involvement of growth hormone (GH) in autoimmune regulation. Previous data on the relationship between the GH/insulin like growth factor-1 (IGF-1) axis and MS/EAE are inconclusive; therefore, the aim of our study was to investigate the changes in the GH axis during acute monophasic EAE. The results show that the gene expression of Ghrh and Sst in the hypothalamus does not change, except for Npy and Agrp, while at the pituitary level the Gh, Ghrhr and Ghr genes are upregulated. Interestingly, the cell volume of somatotropic cells in the pituitary gland remains unchanged at the peak of the disease. We found elevated serum GH levels in association with low IGF-1 concentration and downregulated Ghr and Igf1r expression in the liver, indicating a condition resembling GH resistance. This is likely due to inadequate nutrient intake at the peak of the disease when inflammation in the CNS is greatest. Considering that GH secretion is finely regulated by numerous central and peripheral signals, the involvement of the GH/IGF-1 axis in MS/EAE should be thoroughly investigated for possible future therapeutic strategies, especially with a view to improving EAE disease.

New findings on brain actions of growth hormone and potential clinical implications.

Growth hormone (GH) is secreted by somatotropic cells of the anterior pituitary gland. The classical effects of GH comprise the stimulation of cell proliferation, tissue and body growth, lipolysis, and insulin resistance. The GH receptor (GHR) is expressed in numerous brain regions. Notably, a growing body of evidence indicates that GH-induced GHR signaling in specific neuronal populations regulates multiple physiological functions, including energy balance, glucose homeostasis, stress response, behavior, and several neurological/cognitive aspects. The importance of central GHR signaling is particularly evident when the organism is under metabolic stress, such as pregnancy, chronic food deprivation, hypoglycemia, and prolonged exercise. These particular situations are associated with elevated GH secretion. Thus, central GH action represents an internal signal that coordinates metabolic, neurological, neuroendocrine, and behavioral adaptations that are evolutionarily advantageous to increase the chances of survival. This review summarizes and discusses recent findings indicating that the brain is an important target of GH, and GHR signaling in different neuronal populations regulates essential physiological functions.

Involvement of Sirtuin 1 in the Growth Hormone/Insulin-like Growth Factor 1 Signal Transduction and Its Impact on Growth Processes in Children.

The regulation of growth processes in children depends on the synthesis of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Insulin-like growth factor 1, which is mainly secreted in the liver in response to GH, is the main peripheral mediator of GH action. Newly discovered factors regulating GH secretion and its effects are being studied recently. One of them is sirtuin 1 (SIRT1). This NAD+-dependent deacetylase, by modulating the JAK2/STAT pathway, is involved in the transduction of the GH signal in hepatocytes, leading to the synthesis of IGF-1. In addition, it participates in the regulation of the synthesis of GHRH in the hypothalamus and GH in the somatotropic cells. SIRT1 is suggested to be involved in growth plate chondrogenesis and longitudinal bone growth as it has a positive effect on the epiphyseal growth plate. SIRT1 is also implicated in various cellular processes, including metabolism, cell cycle regulation, apoptosis, oxidative stress response, and DNA repair. Thus, its expression varies depending on the different metabolic states. During malnutrition, SIRT1 blocks GH signal transduction in hepatocytes to reduce the IGF-1 secretion and prevent hypoglycemia (i.e., it causes transient GH resistance). In this review, we focused on the influence of SIRT1 on GH signal transduction and the implications that may arise for growth processes in children.

Characterization of Somatotrope Cell Expansion in Response to GHRH in the Neonatal Mouse Pituitary.

In humans and mice, loss-of-function mutations in growth hormone-releasing hormone receptor (GHRHR) cause isolated GH deficiency. The mutant GHRHR mouse model, GhrhrLit/Lit (LIT), exhibits loss of serum GH, but also fewer somatotropes. However, how loss of GHRH signaling affects expansion of stem and progenitor cells giving rise to GH-producing cells is unknown. LIT mice and wild-type littermates were examined for differences in proliferation and gene expression of pituitary lineage markers by quantitative reverse transcription polymerase chain reaction and immunohistochemistry at postnatal day 5 (p5) and 5 weeks. At p5, the LIT mouse shows a global decrease in pituitary proliferation measured by proliferation marker Ki67 and phospho-histone H3. This proliferative defect is seen in a pituitary cell expressing POU1F1 with or without GH. SOX9-positive progenitors show no changes in proliferation in p5 LIT mice. Additionally, the other POU1F1 lineage cells are not decreased in number; rather, we observe an increase in lactotrope cell population as well as messenger RNA for Tshb and Prl. In the 5-week LIT pituitary, the proliferative deficit in POU1F1-expressing cells observed neonatally persists, while the number and proliferative proportion of SOX9 cells do not appear changed. Treatment of cultured pituitary explants with GHRH promotes proliferation of POU1F1-expressing cells, but not GH-positive cells, in a mitogen-activated protein kinase-dependent manner. These findings indicate that hypothalamic GHRH targets proliferation of a POU1F1-positive cell, targeted to the somatotrope lineage, to fine tune their numbers.

Intrathymic somatotropic circuitry: consequences upon thymus involution.

Growth hormone (GH) is a classic pituitary-derived hormone crucial to body growth and metabolism. In the pituitary gland, GH production is stimulated by GH-releasing hormone and inhibited by somatostatin. GH secretion can also be induced by other peptides, such as ghrelin, which interacts with receptors present in somatotropic cells. It is well established that GH acts directly on target cells or indirectly by stimulating the production of insulin-like growth factors (IGFs), particularly IGF-1. Notably, such somatotropic circuitry is also involved in the development and function of immune cells and organs, including the thymus. Interestingly, GH, IGF-1, ghrelin, and somatostatin are expressed in the thymus in the lymphoid and microenvironmental compartments, where they stimulate the secretion of soluble factors and extracellular matrix molecules involved in the general process of intrathymic T-cell development. Clinical trials in which GH was used to treat immunocompromised patients successfully recovered thymic function. Additionally, there is evidence that the reduction in the function of the somatotropic axis is associated with age-related thymus atrophy. Treatment with GH, IGF-1 or ghrelin can restore thymopoiesis of old animals, thus in keeping with a clinical study showing that treatment with GH, associated with metformin and dehydroepiandrosterone, could induce thymus regeneration in healthy aged individuals. In conclusion, the molecules of the somatotrophic axis can be envisioned as potential therapeutic targets for thymus regeneration in age-related or pathological thymus involution.

Increased GH Secretion and Body Growth in Mice Carrying Ablation of IGF-1 Receptor in GH-releasing Hormone Cells

Growth hormone (GH) secretion is controlled by short and long negative feedback loops. In this regard, both GH (short-loop feedback) and insulin-like growth factor 1 (IGF-1; long-loop feedback) can target somatotropic cells of the pituitary gland and neuroendocrine hypothalamic neurons to regulate the GH/IGF-1 axis. GH-releasing hormone (GHRH)-expressing neurons play a fundamental role in stimulating pituitary GH secretion. However, it is currently unknown whether IGF-1 action on GHRH-expressing cells is required for the control of the GH/IGF-1/growth axis. In the present study, we investigated the phenotype of male and female mice carrying ablation of IGF-1 receptor (IGF1R) exclusively in GHRH cells. After weaning, both male and female GHRHΔIGF1R mice exhibited increases in body weight, lean body mass, linear growth, and length of long bones (tibia, femur, humerus, and radius). In contrast, the percentage of body fat was similar between control and GHRHΔIGF1R mice. The higher body growth of GHRHΔIGF1R mice can be explained by increases in mean GH levels, GH pulse amplitude, and pulse frequency, calculated from 36 blood samples collected from each animal at 10-minute intervals. GHRHΔIGF1R mice also showed increased hypothalamic Ghrh mRNA levels, pituitary Gh mRNA expression, hepatic Igf1 expression, and serum IGF-1 levels compared with control animals. Furthermore, GHRHΔIGF1R mice displayed significant alterations in the sexually dimorphic hepatic gene expression profile, with a prevailing feminization in most genes analyzed. In conclusion, our findings indicate that GHRH neurons represent a key and necessary site for the long-loop negative feedback that controls the GH/IGF-1 axis and body growth.

Comparative microscopic and electron microscopic study of somatotropic pituitary cells in two rare mammalian species

The aim of this study was to find out the microscopic and ultrastructural features of somatotropic endocrinocytes in two rare mammalian species in postnatal ontogenesis.Material and methods. We used material from river beavers (Castor fiber L.) and sea otters (sea beaver, Enhydra lutris), listed in the Red Book of the Russian Federation. The collection of material was carried out in the Voronezh Reserve and on the rookeries of marine mammals on the Commander Islands (Bering Island, Medny Island). To fix the material, Shteve, Bouin, and Zenker liquids were used. Paraffin sections were stained with hematoxylin and eosin, aldehyde fuchsin according to Helmi–Dyban. The linear dimensions of cell structures were measured, the cross-sectional area of cells and their nuclei was calculated, and the nuclear cytoplasmic index was calculated. The numerical density of somatotropic endocrinocytes in the field of view was determined. For electron microscopy, pituitary specimens were fixed in 2.5% glutaraldehyde and 1% osmium fixative. Sections were prepared on BS-490 and LKB-4800 ultramicrotomes. Sections were counterstained with uranyl acetate and lead citrate and studied under a Tesla BS-500 electron microscope.Results. In river beavers and sea otters at the age of 6 months, compared with newborn animals, the number of somatotropic cells in the center of the pituitary gland increases by 3.46 (p<0.05) and 3.32 times (p<0.05), respectively, and in the lateral zones – 2.61 times (p<0.05) and 3.39 times (p<0.05); cell cytoplasm area – 1.96 times (p<0.05) and 1.85 times (p<0.05); the area of the nuclei – 1.48 times (p<0.05) and 1.30 times (p<0.05). In river beavers and sea otters at the age of one year, compared with six-month-old animals, an increase in the number of somatotropic cells in the center of the pituitary gland by 1.27 times (p<0.05) and 1.33 times (p<0.05) was revealed; and in the lateral zones by 1.08 times (p<0.05) and 1.02 times (p>0.05); and area of the cytoplasm of cells, respectively – 1.29 times (p<0.05) and. 1.25 times (p<0.05). The maximum indicators of secretory activity of somatotropic cells were found in river beavers and sea otters at the age of 1 year.

GPR101 drives growth hormone hypersecretion and gigantism in mice via constitutive activation of G s and G q/11

Growth hormone (GH) is a key modulator of growth and GH over-secretion can lead to gigantism. One form is X-linked acrogigantism (X-LAG), in which infants develop GH secreting pituitary tumors over-expressing the orphan G-protein coupled receptor, GPR101. The role of GPR101 in GH secretion remains obscure. We studied GPR101 signaling pathways and their effects in HEK293 and rat pituitary GH3 cell lines, human tumors and in transgenic mice with elevated somatotrope Gpr101 expression driven by the rat Ghrhr promoter (GhrhrGpr101). We report that Gpr101 causes elevated GH/prolactin secretion in transgenic GhrhrGpr101mice. We also show that GPR101 promotes GH secretion through the activation of not only Gs, but also Gq/11, in a PKA and PKC-dependent manner, respectively. Interestingly, in stark contrast with other Gs-coupled receptors, GPR101 activation did not lead to the proliferation of somatotrope cells. These signatures of GPR101 signaling, notably PKC activation, are also present in human X-LAG pituitary tumors with high GPR101 expression. These results underline a role for GPR101 in the regulation of somatotrope axis function.

Intra-molecular Conformational Stability in Human Growth Hormone

Human growth hormone (hGH) is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior lobe of pituitary glands; and is transported to other organs of human body. Study of intra-molecular structure and its binding mechanisms within the molecule gives more insight of structural stability of the molecule and is also essential in drug designing. In this article, we have investigated the various bonded and non-bonded interactions that contribute for the conformation of entire structure of the hGH molecule using molecular dynamics (MD) simulation. The MD outcomes show that the molecule is hydrophobic in nature. In its conformation, several types of interactions exist, such as disulphide bridges (bonded) and nonbonded: hydrogen bond, hydrophobic, aromatic-aromatic, ionic, aromatic-sulphur, cation-pi.

Control of the Anterior Pituitary Cell Lineage Regulator POU1F1 by the Stem Cell Determinant Musashi.

The adipokine leptin regulates energy homeostasis through ubiquitously expressed leptin receptors. Leptin has a number of major signaling targets in the brain, including cells of the anterior pituitary (AP). We have previously reported that mice lacking leptin receptors in AP somatotropes display growth hormone (GH) deficiency, metabolic dysfunction, and adult-onset obesity. Among other targets, leptin signaling promotes increased levels of the pituitary transcription factor POU1F1, which in turn regulates the specification of somatotrope, lactotrope, and thyrotrope cell lineages within the AP. Leptin's mechanism of action on somatotropes is sex dependent, with females demonstrating posttranscriptional control of Pou1f1 messenger RNA (mRNA) translation. Here, we report that the stem cell marker and mRNA translational control protein, Musashi1, exerts repression of the Pou1f1 mRNA. In female somatotropes, Msi1 mRNA and protein levels are increased in the mouse model that lacks leptin signaling (Gh-CRE Lepr-null), coincident with lack of POU1f1 protein, despite normal levels of Pou1f1 mRNA. Single-cell RNA sequencing of pituitary cells from control female animals indicates that both Msi1 and Pou1f1 mRNAs are expressed in Gh-expressing somatotropes, and immunocytochemistry confirms that Musashi1 protein is present in the somatotrope cell population. We demonstrate that Musashi interacts directly with the Pou1f1 mRNA 3' untranslated region and exerts translational repression of a Pou1f1 mRNA translation reporter in a leptin-sensitive manner. Musashi immunoprecipitation from whole pituitary reveals coassociated Pou1f1 mRNA. These findings suggest a mechanism in which leptin stimulation is required to reverse Musashi-mediated Pou1f1 mRNA translational control to coordinate AP somatotrope function with metabolic status.

Acromegaly - dealing with an uncooperative patient

Introduction: Acromegaly is a chronic disease resulting from increased secretion of growth hormone. The main reason of elevated GH concentration is pituitary adenoma that originates from somatotropic cells. As a consequence, several changes in the organism appear such as progressive deformation of the skeleton with enlargement of the skull, hands and feet, growth of soft tissues, bones and internal organs as well as many other systemic complications which are responsible for increased mortality in untreated patients. Case report: A 60-year-old patient was diagnosed with acromegaly due to the pituitary macroadenoma and associated hypopituitarism in the thyroid and gonadotropic axis 4 years ago. The disease was suspected in April 2016 by a rheumatologist, and then confirmed on the basis of hormonal tests in the Endocrinology Clinic (IGF1 - 754.7 ng/ml, N: 77-224; GH - 2.51 ng/ml, no inhibition in OGTT). The imaging examination revealed a pituitary macroadenoma with dimensions of 17x15x19 mm. The medical history revealed the characteristic symptoms of acromegaly like enlargement and deformation of the fingers, enlarged nose, excessive sweating and headaches for the last 12 years. There have been several studies investigating the complications of acromegaly that found abnormalities in the cardiovascular system, metabolic disorders (dyslipidemia, abnormal fasting glycaemia), arthropathies, sigmoid polyps and nodular goiter. Due to the patient's lack of consent to the surgical intervention, treatment with a somatostatin analogue was introduced. During 2-year therapy, the normalization of IGF-1 concentration was not achieved. In October 2018 patient completely abandoned therapy with somatostatin analogue. In 2019 the lack of control of acromegaly was confirmed. During hospitalization in 2020 the uncontrolled acromegaly was stated once again. The patient still does not consent to the surgical procedure to remove pituitary macroadenoma, however, he agreed for systematic re-treatment with a somatostatin analogue. Conclusions: Isolated pharmacological treatment doesn’t always allow for sufficient control of an illness. Effective treatment of acromegaly should consist of surgery as well as conservative treatment. The introductinon of both 2nd generation analogues and GH receptor antagonists in therapeutic programs makes effective pharmacological treatment possible.

System of Criteria for Treatment Evaluation of Acromegaly in Bulgaria.

Acromegaly is a rare endocrine disorder caused by excessive and longstanding secretion of growth hormone (GH) by the pituitary somatotroph and resulting from this overproduction of insulin-like growth factor-1 hormone (IGF-1) by the liver. There are few registers and rather limited clinical data about acromegaly treatment. The analysis of acromegaly data is rarely subject to a system of criteria for evaluating acromegaly treatment. The novelty of this paper is that it presents a real- life practice case study about the implementation results of such a system in Bulgaria. The case study analysis illustrates a clinical information approach to manage thousands of records in the Bulgarian Acromegaly Database. The here reported results provide evidence about the difficulties in maintaining both GH and IGF-1 levels inside their reference values in acromegaly treatment. Ongoing research extends the evaluation results by enabling semantic interoperability between acromegaly databases based on openEHR specification.

SAT-255 Pituitary Adenoma With TSH and GH Co Secretion

Introduction:Thyrotropinomas are rare pituitary adenomas, representing 2% of pituitary tumors.They are characterized by autonomous secretion of thyrotropin (TSH) and elevated levels of peripheral hormones.A third can secrete other hormones, including growth hormone (GH).We present the case of a patient with hypersecretion TSH and GH with clinical manifestations.Clinical case:44-year-old woman with a history of palpitations and weight loss of 8 kilos of 3 months of evolution, as well as decreased visual acuity and headache.Physical exam: tachycardia, fine tremor, prognathism, thickening of the lips, increase in the base of the nose, hands and feet.TSH; 8.8mU / L (0.4-4), FT4: 35.59pg / ml (8-17), GH: 3.93 (less than 1.88), IGF-1: 716ng / ml (101-267), ANTI TPO negative, FSH, LH, Estradiol, Prolactin, Cortisol in range. Thyroid profile is repeated: TSH: 12.92mIU / ml (0.34-4.94); FT4 and T3 high.Campimetry: left temporal hemianopiaPituitary MRI: a heterogeneous 51x42x47mm Turkish chair mass with sphenoid sinus invasion and right cavernosum with vascular structures encompassing.Thyroid ultrasound: normalMethimazole and octeotride LAR are initiated and in June 2018, a transcranial approach and partial resection of the pituitary macroadenoma is performed.In August 2019, hormonal profile IGF1: 470 ng / ml, TSH: 2.7 uUI / ml, T3 207 ng / dl.Pituitary MRI showing evidence of selar, sphenoid expansive lesion with bilateral carotid invasion, bitemporal hemiapnosia, acromegalics facial features and acral growth without signs of hyperthyroidism.Neurosurgery decides to perform a tranesphenoidal approach and partial tumor resection without postoperative complications; The immunohistochemical study reveals GH positive, nonspecific TSH, KI 7% P53 20%. LAR octeotride is suspended.In September 2019, the homonal profile reports IGF1 177ng / ml, TSH: 4.39 uUI / ml, FT4 7.14 ug / dl and T3 50ng / dl, the signs of acromegaly disappear.Discussion.Thyrotropinomas are rare, even more so if they are multi-hormonal, usually they secrete one hormone or another or they are silent. Thyrotropic and somatotropic cells share common transcription factors: Pit-1 and Prop-1.Most of these tumors are silent or manifest clinically with TSH secretion. The case presented has the particularity of expressing clinical characteristics of both GH and TSH secretion.Preoperative treatment with somatostatin analogues can reduce tumor size and control hormonal hypersecretion. Radiation therapy is an alternative in case of unsatisfactory results after surgery.Multi-hormonality predicts a higher risk of recurrence than the secretory tumors of only one hormone, so monitoring these patients is essential.

Increased E2F1 mRNA and miR-17-5p Expression Is Correlated to Invasiveness and Proliferation of Pituitary Neuroendocrine Tumours.

miR-17-5p and E2F1 have been described as deregulated in cancer, but they have scarcely been studied in pituitary neuroendocrine tumours (PitNETs). This study evaluates the relationship of E2F1 and miR-17-5p with the invasiveness and proliferation of PitNETs. In this cross-sectional descriptive study, we evaluated the expression of E2F1, MYC, and miR-17-5p by quantitative real time PCR analysis in 60 PitNETs: 29 gonadotroph (GT), 15 functioning somatotroph (ST), and 16 corticotroph (CT) tumours, of which 8 were silent (sCT). The clinical data were collected from the Spanish Molecular Register of Pituitary Adenomas (REMAH) database. We defined invasiveness according to the Knosp classification and proliferation according to a molecular expression of Ki-67 ≥ 2.59. E2F1 was more expressed in invasive than in non-invasive tumours in the whole series (p = 0.004) and in STs (p = 0.01). In addition, it was overexpressed in the silent subtypes (GTs and sCTs; all macroadenomas) and normoexpressed in the functioning ones (fCTs and STs; some microadenomas). miR-17-5p was more expressed in proliferative than in non-proliferative tumours (p = 0.041) in the whole series but not by subtypes. Conclusions: Our study suggests that in PitNETs, E2F1 could be a good biomarker of invasiveness, and miR-17-5p of proliferation, helping the clinical management of these tumours.

Influence of insulin on growth hormone secretion, level and growth hormone signalling.

Growth hormone (GH), as a vital hormone, has to experience a series of processes to fulfill its function including secretion, entering the circulation to reach target tissues (pre-receptor process), binding on the GH receptor (GHR) and triggering signaling inside cells (post-GHR process). Insulin can directly or indirectly influence part of these processes. GH secretion from pituitary somatotropes is regulated by GH-releasing hormone (GHRH) and somatostatin (SS) from hypothalamus. Insulin may exert positive or negative effects on the neurons expressing GHRH and SS and somatotropes under healthy and pathological conditions including obesity and diabetes. Glucose and lipid levels in circulation and dietary habits may influence the effect of insulin on GH secretion. Insulin may also affect GHR sensitivity and the level of insulin-like growth factor 1 (IGF-1), thus influence the level of GH. The GH signaling is also important for GH to play its role. GH signaling involves GHR/JAK2/STATs, GHR/JAK2/SHC/MAPK and GH/insulin receptor substrate (IRS)/PI3K/Akt pathways. These pathways may be shared by insulin, which is the basis for the interaction between insulin and GH, and insulin may attenuate or facilitate the GH signal by influencing molecules in the pathways. Many factors are related to the effect of insulin, among them the most important ones are duration of action and amount of insulin. The tendency of insulin-reduced GH signaling becomes obvious with increased dose and acting time of insulin. The participation of suppressor of cytokine signaling (SOCS), the interaction between JAK2 and IRS, and GHR sensitivity should also be considered when discovering GH signal. The involvement of SS in response to insulin is not clear yet. The details of how GH secretion, level and signaling change in response to time and dose of insulin treatment warrant further studies.

An improved method of culturing somatotropic cells from rat adenohypophysis

This study aimed to propose a simple and practical method for culturing primary rat somatotropic cells in vitro free of pericytes contamination. Rat adenohypophyses were randomly divided into two groups. An improved method was used in group A (digesting adenohypophysis with 0.25% trypsin-EDTA, followed by removing pericytes by double filtration and using serum-free medium for culturing somatotropic cells). The traditional method was used in group B (digesting adenohypophysis with 0.35% collagenase, using serum medium for culturing somatotropic cells, and removing pericytes by changing the culture dish). The numbers and viability of somatotropic cells were higher in group A than in group B after 6 days. GH secretion of somatotropic cells was also higher in group A than in group B. Besides, the pericytes grew rapidly only in group B after 3 days. α-SMA, type I collagen, and type III collagen had weaker expression in group A. Also, the viability of pericytes decreased in group A. The improved method could solve the problem of pericytes contamination, and the culture of primary rat somatotropic cells in vitro was successful. This method can be used for other primary cultures with pericytes contamination.

MON-465 SST2 Trafficking Through The Cytoskeleton: Role Of Scaffolding Proteins Filamin A And β-arrestin 2

The high expression level of somatostatin receptor 2 (SST2) in growth hormone (GH)-secreting tumors represents the rationale for the clinical use of somatostatin analogs (SSAs) in acromegaly. However, about one third of patients displays resistance to SSAs and, to date, the underlying molecular mechanisms are still under investigation. Recently, the cytoskeletal protein Filamin A (FLNA) and the scaffolding proteins β-arrestins have emerged as key modulators of the responsiveness of GH-secreting pituitary tumors to SSAs, by regulating SST2 signaling and desensitization, respectively. The aim of this study was to further explore FLNA involvement in SST2 intracellular trafficking in somatotrope cells, since alterations in this system might affect the amount of available receptor at the plasma membrane and lead to unresponsive tumor features.By biotinylation assay we first found that FLNA silencing strongly reduced octreotide-mediated SST2 internalization in rat GH3 cell line (26.9±2.7% vs 4±1.7% SST2 internalization, control vs FLNA siRNA cells, respectively, P<0.001) and in one human GH-secreting primary culture tested (93.2% vs 31.6% SST2 internalization, control vs FLNA siRNA cells, respectively). Then, co-immunoprecipitation and immunofluorescence experiments performed in GH3 cells showed that FLNA knock down did not prevent the recruitment of β-arrestin2 to cell surface ligand-activated SST2, but rather impaired receptor localization into cytosolic vesicles positive for the early endocytic marker Rab5 (Pearson’s coefficient mean 0.29±0.07 vs 0.16±0.03 of SST2-Rab5 colocalization in control vs FLNA siRNA, P<0.01). Furthermore, after octreotide removal, SST2 recycling fate was affected by the loss of FLNA. Conversely to control cells, SST2 failed to accumulate into intracellular recycling vesicles linked to the early recycling marker Rab4, as resulted by Rab4-SST2 colocalizaition analysis (Pearson’s coefficient mean 0.24±0.05 vs 0.16±0.04 of SST2-Rab4 colocalization in control vs FLNA siRNA, P<0.05) and could not reach the plasma membrane in wash out experiments. Altogether these data unveil a crucial role of FLNA in the regulation of octreotide-induced SST2 trafficking in GH-secreting cells, suggesting the possibility of targeting FLNA-SST2 complexes for the treatment of pharmacologically resistant GH-secreting pituitary tumors.