Pituitary GH Research Articles

Differences in the efficacy of second-line therapies on the biochemical control of acromegaly in patients with GH secreting pituitary neuroendocrine tumors (Pit-NETs) and GH and PRL cosecreting Pit-NETs

Differences in the efficacy of second-line therapies on the biochemical control of acromegaly in patients with GH secreting pituitary neuroendocrine tumors (Pit-NETs) and GH and PRL cosecreting Pit-NETs

Neuregulin 4 (Nrg4) cooperates with melatonin to regulate the PRL expression via ErbB4/Erk signaling pathway as a potential prolactin (PRL) regulator.

Neuregulin-4 (Nrg4) and melatonin play vital roles in endocrine diseases. However, there is little discussion about the function and potential mechanism of Nrg4 and melatonin in prolactin (PRL) regulation. The human normal pituitary data from Gene Expression Profiling Interactive Analysis (GEPIA) database was used to explore the correlation between NRG4 and PRL. The expression and correlation of NRG4 and PRL were determined by Immunofluorescence staining (IF) and human normal pituitary tissue microarray. Western Blot (WB) was used to detect the expression of PRL, p-ErbB2/3/4, ErbB2/3/4, p-Erk1/2, Erk1/2, p-Akt and Akt in PRL-secreting pituitary GH3 and RC-4B/C cells treated by Nrg4, Nrg4-small interfering RNA, Erk1/2 inhibitor FR180204 and melatonin. The expression of NRG4 was significantly positively correlated with that of PRL in the GEPIA database and normal human pituitary tissues. Nrg4 significantly increased the expression and secretion of PRL and p-Erk1/2 expression in GH3 cells and RC-4B/C cells. Inhibition of Nrg4 significantly inhibited PRL expression. The increased levels of p-Erk1/2 and PRL induced by Nrg4 were abolished significantly in response to FR180204 in GH3 and RC-4B/C cells. Additionally, Melatonin promotes the expression of Nrg4, p-ErbB4, p-Erk1/2, and PRL and can further promote the expression of p-Erk1/2 and PRL in combination with Nrg4. Further investigation into the function of Nrg4 and melatonin on PRL expression and secretion may provide new clues to advance the clinical control of prolactinomas and hyperprolactinemia.

Differences between GH and PRL co-secreting and GH-secreting pituitary adenomas. A series of 604 cases.

To evaluate differences in clinical presentation and in surgical outcomes between growth hormone-secreting pituitary adenomas (GH-PAs) and GH and prolactin co-secreting pituitary adenomas (GH&PRL-PAs). Multicenter retrospective study of 604 patients with acromegaly submitted to pituitary surgery. Patients were classified into two groups according to serum PRL levels at diagnosis and immunohistochemistry (IHC) for PRL: a) GH&PRL-PAs when PRL levels were above the upper limit of normal and IHC for GH and PRL was positive or PRL levels were >100ng/and PRL IHC was not available (n=130) and b) GH-PAs who did not meet the previously mentioned criteria (n=474). GH&PRL-PAs represented 21.5% (n=130) of patients with acromegaly. The mean age at diagnosis was lower in GH&PRL-PAs than in GH-PAs (P<0.001). GH&PRL-PAs were more frequently macroadenomas (90.6% vs. 77.4%, P=0.001) and tended to be more invasive (33.6% vs. 24.7%, P=0.057) than GH-PAs. Furthermore, they had presurgical hypopituitarism more frequently (OR 2.8, 95% CI 1.83-4.38). IGF-1 upper limit of normality (ULN) levels at diagnosis were lower in patients with GH&PRL-PAs (median 2.4 [IQR 1.73-3.29] vs. 2.7 [IQR 1.91-3.67], P=0.023). There were no differences in the immediate (41.1% vs 43.3%, P=0.659) or long-term post-surgical acromegaly biochemical cure rate (53.5% vs. 53.1%, P=0.936) between groups. However, there was a higher incidence of permanent arginine-vasopressin deficiency (AVP-D) (7.3% vs. 2.4%, P=0.011) in GH&PRL-PAs patients. GH&PRL-PAs are responsible for 20% of acromegaly cases. These tumors are more invasive, larger and cause hypopituitarism more frequently than GH-PAs and are diagnosed at an earlier age. The biochemical cure rate is similar between both groups, but patients with GH&PRL-PAs tend to develop permanent postsurgical AVP-D more frequently.

Identification and functional analysis of first heterozygous frameshift mutation in the GHRH gene in a Chinese boy with isolated growth hormone deficiency

BackgroundIsolated growth hormone deficiency (IGHD) is a rare genetically heterogeneous disorder caused primarily by mutations in GH1 and GH releasing hormone receptor (GHRHR). The aim of this study was to identify the molecular etiology of a Chinese boy with IGHD. MethodsWhole-exome sequencing, sanger sequencing and bioinformatic analysis were performed to screen for candidate mutations. The impacts of candidate mutation on gene expression, intracellular localization and protein function were further evaluated by in vitro assays. ResultsA novel heterozygous frameshift mutation in the GHRH gene (c.91dupC, p.R31Pfs*98) was identified in a Chinese boy clinically diagnosed as having IGHD. The mutation was absent in multiple public databases, and considered as deleterious using in silico prediction, conservative analysis and three-dimensional homology modeling. Furthermore, mRNA and protein expression levels of mutant GHRH were significantly increased than wild-type GHRH (p < 0.05). Moreover, mutant GHRH showed an aberrant accumulation within the cytoplasm, and obviously reduced ability to stimulate GH secretion and cAMP accumulation in human GHRHR-expressing pituitary GH3 cells compared to wild-type GHRH (p < 0.05). ConclusionOur study discovered the first loss-of function mutation of GHRH in a Chinese boy with IGHD and provided new insights on IGHD pathogenesis caused by GHRH haploinsufficiency.

Safinamide, an inhibitor of monoamine oxidase, modulates the magnitude, gating, and hysteresis of sodium ion current

BackgroundSafinamide (SAF), an α-aminoamide derivative and a selective, reversible monoamine oxidase (MAO)-B inhibitor, has both dopaminergic and nondopaminergic (glutamatergic) properties. Several studies have explored the potential of SAF against various neurological disorders; however, to what extent SAF modulates the magnitude, gating, and voltage-dependent hysteresis [Hys(V)] of ionic currents remains unknown.MethodsWith the aid of patch-clamp technology, we investigated the effects of SAF on voltage-gated sodium ion (NaV) channels in pituitary GH3 cells.ResultsSAF concentration-dependently stimulated the transient (peak) and late (sustained) components of voltage-gated sodium ion current (INa) in pituitary GH3 cells. The conductance–voltage relationship of transient INa [INa(T)] was shifted to more negative potentials with the SAF presence; however, the steady-state inactivation curve of INa(T) was shifted in a rightward direction in its existence. SAF increased the decaying time constant of INa(T) induced by a train of depolarizing stimuli. Notably, subsequent addition of ranolazine or mirogabalin reversed the SAF-induced increase in the decaying time constant. SAF also increased the magnitude of window INa induced by an ascending ramp voltage Vramp. Furthermore, SAF enhanced the Hys(V) behavior of persistent INa induced by an upright isosceles-triangular Vramp. Single-channel cell-attached recordings indicated SAF effectively increased the open-state probability of NaV channels. Molecular docking revealed SAF interacts with both MAO and NaV channels.ConclusionSAF may interact directly with NaV channels in pituitary neuroendocrine cells, modulating membrane excitability.

Inhibitory Perturbations of Fluvastatin on Afterhyperpolarization Current, Erg-mediated K+ Current, and Hyperpolarization-activated Cation Current in Both Pituitary GH3 Cells and Primary Embryonic Mouse Cortical Neurons.

Fluvastatin (FLV), the first synthetically derived 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, is a potent inhibitor of cholesterol biosynthesis. While its primary mechanism of action is to reduce cholesterol levels, there is some evidence suggesting that it may also have effects on K+ channels. However, the overall effects of fluvastatin on ionic currents are not yet well understood. The whole-cell clamp recordings were applied to evaluate the ionic currents and action potentials of cells. Here, we have demonstrated that FLV can effectively inhibit the amplitude of erg-mediated K+ current (IK(erg)) in pituitary tumor (GH3) cells, with an IC50 of approximately 3.2µM. In the presence of FLV, the midpoint in the activation curve of IK(erg) was distinctly shifted to a less negative potential by 10mV, with minimal modification of the gating charge. However, the magnitude of hyperpolarization-activated cation current (Ih) elicited by long-lasting membrane hyperpolarization was progressively decreased, with an IC50 value of 8.7µM, upon exposure to FLV. More interestingly, we also found that FLV (5µM) could regulate the action potential and afterhyperpolarization properties in primary embryonic mouse cortical neurons. Our study presents compelling evidence indicating that FLV has the potential to impact both the amplitude and gating of the ion channels IK(erg) and Ih. We also provide credible evidence suggesting that this drug has the potential to modify the properties of action potentials and the afterhyperpolarization current in electrically excitable cells. However, the assumption that these findings translate to similar in-vivo results remains unclear.

THU083 Disulfiram Mediated Anti-tumor Effect In Pituitary Neuroendocrine Tumors By Inducing Cuproptosis

Abstract Disclosure: N. Huang: None. Y. Zhang: None. Y. Liu: None. Y. Feng: None. L. Xue: None. Z. Wu: None. Pituitary neuroendocrine tumors (PitNETs) are common intracranial tumors. Dopamine agonists and somatostatin analogues are the first-line drugs for PRL and GH-secreting PitNETs clinically. However, there is no effective drug for other subtypes and drug-resistant PitNETs. Thus, it’s impending to discover new therapeutic targets and medicine. Cuproptosis is a copper-dependent form of cell death driven by lipoylated protein aggregation, loss of Fe-S cluster-containing proteins, and induction of HSP70. However, the role of cuproptosis in PitNETs is not clear. In this study, a total of 17 primary samples of PitNETs were collected to perform high-throughput drug screening, an anti-abuse drug disulfiram (DSF) was identified that can induce cell death effectively. We found that disulfiram also has a strong inhibitory effect on pituitary tumor cell lines MMQ, Att20 and GH3 (-87.1%, -62.5%, -92.7%, p&amp;lt;0.001), but the inhibitory effect was eliminated by copper chelator TTM/BCS. This indicated that DSF played the anti-tumor effect requiring the participation of copper ions. To explore the underlying mechanism that DSF induces the cell death of PitNETs, we detected the hallmark of cuproptosis and found that DSF leads to a decrease in the acylation level of proteins related to the tricarboxylic acid cycle, limiting the function of the protein. On the one hand, DSF leads to the downregulation of iron-sulfur cluster-associated proteins, and the oligomerization of dihydrolipoamide S-acetyltransferase (DLAT), which is eventually accompanied by an increase in the protein level of heat shock protein 70 (HSP70) at protein and mRNA level, causing proteotoxic stress leading to cell death. Finally, DSF treatment inhibited the tumor growth in MMQ cell transplanted mouse model and destructed the morphology of the pituitary tumor 3D sphere similarly demonstrating the inhibition effect. In conclusion, we find that the anti-abuse drug disulfiram can induce coproptosis in pituitary tumor cells in a copper-dependent manner and is a potential drug for the treatment of PitNETs. Presentation: Thursday, June 15, 2023

FRI370 Hyperthyroidism And Acromegaly In A Patient With A Mature Plurihormonal PIT1 Lineage PitNET/Adenoma

Abstract Disclosure: D. Slack: None. A.C. Levine: None. Background: TSH- and GH-secreting pituitary neuroendocrine tumors (PitNETs) are both rare entities, with an incidence of 1 per million people and 1-4 per million people, respectively. Thyrotroph, somatotroph, and lactotroph cells have the same progenitor, regulated by the PIT1 transcription factor. Thus, it is not unusual for PIT1 positive tumors to exhibit immunhistochemical expression of TSH, GH, and prolactin. It is vanishingly rare, however, for these tumors to secrete multiple biologically active hormones with apparent clinical sequelae. We herein report on a case of a patient with a plurihormonal PIT1 lineage PitNET secreting prolactin with secondary amenorrhea, TSH causing central hyperthyroidism and GH resulting in acromegaly. Clinical Case: A 42-year-old woman with a 1-year history of amenorrhea presented with 3 months of progressive weight loss, fatigue, palpitations, and tremulousness. She was found to have central hyperthyroidism, with an elevated free T4 (&amp;gt;7.77 ng/dL, nl 0.82 – 1.77) and inappropriately normal TSH (3.25 uIU/mL, nl 0.45 – 4.5). Full endocrine workup confirmed central hyperthyroidism with elevated free T4 (5.02 ng/dL) and TSH (4.68 uIU/mL) and also demonstrated hyperprolactinemia (122 ng/mL, nl 4.8 – 23.3 ng/mL), elevated IGF-1 (795 ng/mL, nl 91 – 308 ng/mL), GH (19 ng/mL, nl 0 – 10) and free alpha subunit (28 ng/mL, nl &amp;lt;1.02). Over the ensuing 4 months, she noted enlargement of her lips, nose, feet, and hands. MRI demonstrated a pituitary macroadenoma measuring 2.2 cm x 2.7 cm x 2 cm with asymmetric extension into the left cavernous sinus and mild elevation of the adjacent optic chiasm. She underwent an uncomplicated transsphenoidal resection of the tumor with no residual tumor noted on post-op MRI. Discharge medications were hydrocortisone 10 mg AM and, 5 mg early afternoon and levothyroxine 50 mcg daily. One month postoperatively, labs were notable for a low TSH (0.16 mIU/L), normal free T4 (1.62 ng/dL), down-trending IGF-1 (339 ng/mL), and normal prolactin (15.1 ng/mL). Additionally, AM cortisol and ACTH levels remained normal after holding her morning dose of hydrocortisone. She reported resolution of all presenting symptoms of thyrotoxicosis as well as decreasing size of her hands, feet, and nose. Pathology revealed a mature plurihormonal PIT1-lineage PitNET, with immunoreactivity for PIT1, GH, TSH, and prolactin and MIB-1 index of 3%. Conclusion: This case demonstrates the potential for PitNETs to secrete multiple biologically active pituitary hormones, including prolactin, TSH and GH, highlighting the importance of maintaining an index of suspicion for pituitary causes in the evaluation of thyrotoxicosis and of considering the plurihormonal potential of PitNETs in patients presenting with multiple endocrinopathies. Presentation: Friday, June 16, 2023

Cannabidiol Modulates M-Type K+ and Hyperpolarization-Activated Cation Currents.

Cannabidiol (CBD) is a naturally occurring compound found in the Cannabis plant that is known for its potential therapeutic effects. However, its impact on membrane ionic currents remains a topic of debate. This study aimed to investigate how CBD modifies various types of ionic currents in pituitary GH3 cells. Results showed that exposure to CBD led to a concentration-dependent decrease in M-type K+ currents (IK(M)), with an IC50 of 3.6 μM, and caused the quasi-steady-state activation curve of the current to shift to a more depolarized potential with no changes in the curve's steepness. The CBD-mediated block of IK(M) was not reversed by naloxone, suggesting that it was not mediated by opioid receptors. The IK(M) elicited by pulse-train stimulation was also decreased upon exposure to CBD. The magnitude of erg-mediated K+ currents was slightly reduced by adding CBD (10 μM), while the density of voltage-gated Na+ currents elicited by a short depolarizing pulse was not affected by it. Additionally, CBD decreased the magnitude of hyperpolarization-activated cation currents (Ih) with an IC50 of 3.3 μM, and the decrease was reversed by oxaliplatin. The quasi-steady-state activation curve of Ih was shifted in the leftward direction with no changes in the slope factor of the curve. CBD also diminished the strength of voltage-dependent hysteresis on Ih elicited by upright isosceles-triangular ramp voltage. Collectively, these findings suggest that CBD's modification of ionic currents presented herein is independent of cannabinoid or opioid receptors and may exert a significant impact on the functional activities of excitable cells occurring in vitro or in vivo.

Salts of short-chain fatty acids increase the activity of the large conductance, Ca&lt;sup&gt;2+&lt;/sup&gt;-activated K&lt;sup&gt;+&lt;/sup&gt; channels and reduce calcium oscillations in rat GH3 cells

The short-chain fatty acids such as acetic, propionic and butyric acids are microbiota metabolites that can exert a series of physiological effects both in the intestine and other organs, including the central nervous system. The present work aimed to examine the effects of sodium acetate, propionate, and butyrate on the activity of large conductance Ca2+ activated K+ channels and calcium oscillations in rat pituitary GH3 cells. It has been shown that fatty acids under study cause a dose-dependent increase in the amplitude of total outward potassium currents and these effects are prevented by tetraethylammonium, a Ca2+ activated K+ channel blocker, indicating the involvement of Ca2+ activated K+ channels in the effects of fatty acids. It is worthy of note that fatty acids increased open probability of single channels with no changes in the amplitude and the mean channel open time. In addition, fatty acids were associated with a significant reduction in the amplitude and frequency of Ca2+ oscillations in GH3 cells. An increase in potassium conductance and a decrease in the intracellular Ca2+ level can mediate the effects of short-chain fatty acids in various excitable structures, such as a relaxation of intestinal and vascular smooth muscle cells, hyperpolarization of neurons, and the regulation of hormone and neurotransmitter release.

Growth hormone-releasing hormone antagonist MIA-602 inhibits inflammation induced by SARS-CoV-2 spike protein and bacterial lipopolysaccharide synergism in macrophages and human peripheral blood mononuclear cells.

COVID-19 is characterized by an excessive inflammatory response and macrophage hyperactivation, leading, in severe cases, to alveolar epithelial injury and acute respiratory distress syndrome. Recent studies have reported that SARS-CoV-2 spike (S) protein interacts with bacterial lipopolysaccharide (LPS) to boost inflammatory responses in vitro, in macrophages and peripheral blood mononuclear cells (PBMCs), and in vivo. The hypothalamic hormone growth hormone-releasing hormone (GHRH), in addition to promoting pituitary GH release, exerts many peripheral functions, acting as a growth factor in both malignant and non-malignant cells. GHRH antagonists, in turn, display potent antitumor effects and antinflammatory activities in different cell types, including lung and endothelial cells. However, to date, the antinflammatory role of GHRH antagonists in COVID-19 remains unexplored. Here, we examined the ability of GHRH antagonist MIA-602 to reduce inflammation in human THP-1-derived macrophages and PBMCs stimulated with S protein and LPS combination. Western blot and immunofluorescence analysis revealed the presence of GHRH receptor and its splice variant SV1 in both THP-1 cells and PBMCs. Exposure of THP-1 cells to S protein and LPS combination increased the mRNA levels and protein secretion of TNF-α and IL-1β, as well as IL-8 and MCP-1 gene expression, an effect hampered by MIA-602. Similarly, MIA-602 hindered TNF-α and IL-1β secretion in PBMCs and reduced MCP-1 mRNA levels. Mechanistically, MIA-602 blunted the S protein and LPS-induced activation of inflammatory pathways in THP-1 cells, such as NF-κB, STAT3, MAPK ERK1/2 and JNK. MIA-602 also attenuated oxidative stress in PBMCs, by decreasing ROS production, iNOS and COX-2 protein levels, and MMP9 activity. Finally, MIA-602 prevented the effect of S protein and LPS synergism on NF-кB nuclear translocation and activity. Overall, these findings demonstrate a novel antinflammatory role for GHRH antagonists of MIA class and suggest their potential development for the treatment of inflammatory diseases, such as COVID-19 and related comorbidities.

Molnupiravir, a ribonucleoside antiviral prodrug against SARS-CoV-2, alters the voltage-gated sodium current and causes adverse events

Molnupiravir (MOL) is a ribonucleoside prodrug for oral treatment of COVID-19. Common adverse effects of MOL are headache, diarrhea, and nausea, which may be associated with altered sodium channel function. Here, we investigated the effect of MOL on voltage-gated Na+ current (INa) in pituitary GH3 cells. We show that MOL had distinct effects on transient and late INa, in combination with decreased time constant in the slow component of INa inactivation. The 50% inhibitory concentration (IC50) values of MOL for suppressing transient and late INa were 26.1 and 6.3 μM, respectively. The overall steady-state current-voltage relationship of INa remained unchanged upon MOL exposure. MOL-induced alteration of INa may lead to changes in physiological function through sodium channels. Apart from its effect on inhibiting RNA virus replication, MOL exerts inhibitory effects on plasmalemma INa, which might constitute an additional yet crucial underlying mechanism of its pharmacological activity or adverse events.

The GH/IGF axis in the sea lamprey during metamorphosis and seawater acclimation

How the growth hormone (GH)/insulin-like growth factor (IGF) system affects osmoregulation in basal vertebrates remains unknown. We examined changes in the expression of components of the GH/IGF axis and gill ion transporters during metamorphosis and following seawater (SW) exposure of sea lamprey. During metamorphosis, increases in gill nka and nkcc1 and salinity tolerance were accompanied by increases in pituitary gh, liver igf1, gill ghr and igf1, but not liver ghr. SW exposure of fully metamorphosed sea lamprey resulted in slight increases in plasma chloride concentrations after SW exposure, indicating a high level of SW tolerance, but no major changes in mRNA levels of gill ion transporters or components of the GH/IGF axis. Our results indicate that metamorphosis is a critical point in the lifecycle of sea lamprey for stimulation of the GH/IGF axis and is temporally associated with and likely promotes metamorphosis and SW tolerance.

The novel polyfluoroalkyl benzenesulfonate OBS exposure induces cell cycle arrest and senescence of rat pituitary cell GH3 via the p53/p21/RB pathway

Sodium p-perfluorous nonenoxybenzene sulfonate (OBS), an economical alternative to perfluorooctane sulfonate (PFOS) in multiple industrial fields, is widely detected in the environment. The toxicity of OBS has received increasing attention. Pituitary cells are components of the endocrine system and act as vital regulators of homeostatic endocrine balance. However, the effects of OBS on pituitary cells remain unknown. The present study explores the effects of OBS (0.5, 5, and 50 μM) on GH3 rat pituitary cells after treatment for 24, 48, and 72 h. We found that OBS significantly inhibited cell proliferation in GH3 cells with remarkable senescent phenotypes, including enhanced SA-β-gal activity and expression of senescence-associated secretory phenotype (SASP)-related genes, cell cycle arrest, and upregulation of the senescence-related proteins γ-H2A.X and Bcl-2. OBS caused significant cell cycle arrest of GH3 cells at the G1-phase and concomitantly downregulated the expression of some key proteins for the G1/S transition, including cyclin D1 and cyclin E1. Consistently, the phosphorylation of retinoblastoma (RB), which plays a central role in regulating the cell cycle, was prominently reduced after OBS exposure. Furthermore, OBS notably activated the p53-p21 signalling pathway in GH3 cells, as evidenced by increased p53 and p21 expressions, enhanced p53 phosphorylation, and augmented p53 nuclear import. To our knowledge, this study is the first to reveal that OBS triggers senescence in pituitary cells via the p53-p21-RB signalling pathway. Our study demonstrates a novel toxic effect of OBS in vitro, and provides new perspectives for understanding the potential toxicity of OBS.

Mixed corticotropic and somatotropic pituitary adenoma: A case report

Multi-secreting pituitary adenomas are relatively rare. The mixed somatotropic and corticotropic pituitary adenoma is very rare. The most widely described association is that coupling hypersecretion of GH and prolactin. We report the case of a patient with a pituitary adenoma bi-secreting GH and ACTH. He was a 28-year-old patient admitted for pituitary tumor syndrome, cushing syndrome. The hormonal assessment found a dependent ACTH cushing syndrome. The other hypothalamohypophysial axes were without abnormality. The hypothesis of a pituitary adenoma was raised. The brain scan confirmed the diagnosis by showing a macroadenoma with supra-sellar development with infiltration of the cavernous sinus. After trans-sphenoidal surgery, there was a complete regression ofcushing syndrome. The pathology examination showed a pituitary adenoma; at immunohistochemistry cells expressing anti-ACTH and anti - GH antibodies with KI 67 at 1%.

Inhibition of Voltage-Gated Na+ Currents Exerted by KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea), an Inhibitor of Na+-Ca2+ Exchanging Process.

KB-R7943, an isothiourea derivative, has been recognized as an inhibitor in the reverse mode of the Na+-Ca2+ exchanging process. This compound was demonstrated to prevent intracellular Na+-dependent Ca2+ uptake in intact cells; however, it is much less effective at preventing extracellular Na+-dependent Ca2+ efflux. Therefore, whether or how this compound may produce any perturbations on other types of ionic currents, particularly on voltage-gated Na+ current (INa), needs to be further studied. In this study, the whole-cell current recordings demonstrated that upon abrupt depolarization in pituitary GH3 cells, the exposure to KB-R7943 concentration-dependently depressed the transient (INa(T)) or late component (INa(L)) of INa with an IC50 value of 11 or 0.9 μM, respectively. Likewise, the dissociation constant for the KB-R7943-mediated block of INa on the basis of a minimum reaction scheme was estimated to be 0.97 μM. The presence of benzamil or amiloride could suppress the INa(L) magnitude. The instantaneous window Na+ current (INa(W)) activated by abrupt ascending ramp voltage (Vramp) was suppressed by adding KB-R7943; however, subsequent addition of deltamethrin or tefluthrin (Tef) effectively reversed KB-R7943-inhibted INa(W). With prolonged duration of depolarizing pulses, the INa(L) amplitude became exponentially decreased; moreover, KB-R7943 diminished INa(L) magnitude. The resurgent Na+ current (INa(R)) evoked by a repolarizing Vramp was also suppressed by adding this compound; moreover, subsequent addition of ranolazine or Tef further diminished or reversed, respectively, its reduction in INa(R) magnitude. The persistent Na+ current (INa(P)) activated by sinusoidal voltage waveform became enhanced by Tef; however, subsequent application of KB-R7943 counteracted Tef-stimulated INa(P). The docking prediction reflected that there seem to be molecular interactions of this molecule with the hNaV1.2 or hNaV1.7 channels. Collectively, this study highlights evidence showing that KB-R7943 has the propensity to perturb the magnitude and gating kinetics of INa (e.g., INa(T), INa(L), INa(W), INa(R), and INa(P)) and that the NaV channels appear to be important targets for the in vivo actions of KB-R7943 or other relevant compounds.

Thyroid hormone disrupting potentials of benzisothiazolinone in embryo-larval zebrafish and rat pituitary GH3 cell line

Benzisothiazolinone (BIT), one of the most widely used antimicrobial agents in consumer products, has frequently been detected in the water environment. The present study was conducted to determine the adverse effects of BIT on the thyroid neuroendocrine system of zebrafish embryos/larvae. Rat pituitary (GH3) cell line was employed to support the underlying mechanism of thyroid hormone disrupting effects. Significant coagulation and hatching delay were observed in embryos exposed to 30 μg/L of BIT, which in turn remarkably decreased hatchability and larval survival. In BIT-exposed larvae, tshβ, tshr, and trh genes were significantly upregulated along with a decrease in thyroxine and triiodothyronine content, indicating that BIT decreased thyroid hormones and increased thyrotropin-releasing hormone and thyroid stimulating hormone secretion through a feedback circuit. The downregulation of trα and deio2 genes in the zebrafish larvae suggests the inhibition of thyroid hormone receptors and deiodination. Similar to the results in zebrafish, upregulation of tshβ and downregulation of trα, trβ, deio1, and deio2 genes were observed in GH3 cells. Our observations suggest that BIT can decrease the level of thyroid hormones by influencing central regulation, receptor binding, and deiodination.

Enhancing gosling growth and secretion of somatotrophic and thyrotrophic axis hormones through egg turning during incubation

ABSTRACT 1. Growth performance of Yangzhou geese hatched from eggs with turning angles of 50° or 70° was evaluated in association with serum hormones and somatotrophic gene mRNA expression. 2. Egg turning at 70° significantly (P< 0.05) increased hatchability, gosling quality and hatching weight. Gosling post-hatch body weight, leg and breast muscle weight in the 70° turning group was significantly heavier until 50 d of age. 3. Serum concentrations of GH were significantly higher until 30 d of age in the 70° turning group goslings, and those of IGF-I and T3 were higher from hatching to 50 d of age. 4. The mRNA expression of GHRH, pituitary GH, liver and leg muscle IGF-I were all significantly higher at 1 and 30 d of age after hatch, but not at 70 d after hatch, in the 70° turning group. 5. Egg turning at 70° during incubation improves embryo and gosling quality and growth performance through up-regulation of gene expression and secretion of somatotrophic axis hormones, GHRH, GH and IGF-I, as well as T3.

Rufinamide, a Triazole-Derived Antiepileptic Drug, Stimulates Ca2+-Activated K+ Currents While Inhibiting Voltage-Gated Na+ Currents.

Rufinamide (RFM) is a clinically utilized antiepileptic drug that, as a triazole derivative, has a unique structure. The extent to which this drug affects membrane ionic currents remains incompletely understood. With the aid of patch clamp technology, we investigated the effects of RFM on the amplitude, gating, and hysteresis of ionic currents from pituitary GH3 lactotrophs. RFM increased the amplitude of Ca2+-activated K+ currents (IK(Ca)) in pituitary GH3 lactotrophs, and the increase was attenuated by the further addition of iberiotoxin or paxilline. The addition of RFM to the cytosolic surface of the detached patch of membrane resulted in the enhanced activity of large-conductance Ca2+-activated K+ channels (BKCa channels), and paxilline reversed this activity. RFM increased the strength of the hysteresis exhibited by the BKCa channels and induced by an inverted isosceles-triangular ramp pulse. The peak and late voltage-gated Na+ current (INa) evoked by rapid step depolarizations were differentially suppressed by RFM. The molecular docking approach suggested that RFM bound to the intracellular domain of KCa1.1 channels with amino acid residues, thereby functionally affecting BKCa channels' activity. This study is the first to present evidence that, in addition to inhibiting the INa, RFM effectively modifies the IK(Ca), which suggests that it has an impact on neuronal function and excitability.

PMON129 Pituitary Adenoma Co-Secreting GH, Prolactin and ACTH

Abstract Background Pituitary adenomas co-secreting GH, Prolactin and ACTH are rare. Clinical Case A 38-year-old male with a past medical history of depression and type 2 diabetes mellitus was seen in the endocrinology clinic for an evaluation of acromegaly. In the preceding four years, the patient had experienced an enlargement of his hands and feet, hyperhidrosis, development of an underbite, snoring, daytime somnolence, erectile dysfunction, headaches, and blurry vision. His visual fields were normal. Physical exam: BP 137/85, BMI 39 kg/m2. He had coarse facial features, acral changes of his hands and feet, and wide spacing of his teeth. There was a notable absence of facial plethora, abdominal obesity with thin extremities, proximal muscle weakness, purple abdominal striae, and galactorrhea. Initial laboratory results: GH 16.9 ng/mL (0.05-3 ng/ml), IGF-1 1,109 ng/mL (82-242 ng/mL), Prolactin (PRL) 96.9 ng/ml (5-20 ng/ml), testosterone 34 ng/dL (200-1000 ng/dL), LH 2.3 miu/ml (1.4–12 miu/ml), FSH 4.8 miu/ml (1.5-12 miu /ml), ACTH 197.6 pg/mL (7.2- 63.3 pg/mL), 0800 cortisol 16.2 ug/dL (5-29 ug/dL), 24-hour urine free cortisol 56.84 mcg (3.5-40 mcg), HS salivary cortisol 0.242 (&amp;lt;0.359 ug/dL), overnight 1 mg Dexamethasone suppression test cortisol 6.9 mcg/dL (&amp;lt; 1.8 mcg/dL), normal Free T4 and TSH, and A1c 9.7%. A pituitary MRI revealed a 3.9 cm lobulated, intra and supra-sellar mass with mass effect on the optic chiasm and 75% encasement of the left supra-clinoid internal carotid artery. Neurosurgery performed an endoscopic, endonasal partial resection of the pituitary tumor. The histology was diagnostic of an adenoma, and immunohistochemical staining was positive for GH and PRL, but not ACTH. Post-op lab results: GH 1.07 ng/ml, IGF-1 353 ng/ml, PRL 9.6 ng/ml, testosterone 41 ng/dL, ACTH 68.2 pg/ml, cortisol 4.5 ug/dL, 24-hr urine free cortisol 8 mcg, HbA1c 5.7%. Discussion The intent of this case presentation is to report the rare finding of a pituitary tumor co-secreting GH, ACTH, and Prolactin. The diagnosis of acromegaly was confirmed by significant elevations of GH and IGF-1. The diagnosis of subclinical Cushing's disease was confirmed by elevated ACTH level, 24-hr urine free cortisol, and failed dexamethasone suppression test. The elevated PRL may have been due to tumor PRL secretion or stalk effect. The reduction of these parameters after surgery corroborated the presence of pleurihormonal secretion. This patient's findings support screening for co-secretion of multiple pituitary hormones in patients with acromegaly. Reference Pleurihormonal ACTH-GH Adenoma: Case Report and Systematic Literature Review World Neurosurg 2018 114: 158-164 Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.