Pituitary Growth Hormone Research Articles

Combination of macro-TSH and macroprolactinemia phenomena in a patient with autoimmune thyroiditis and vitiligo

Laboratory diagnostic methods are the main tools in the practice of a doctor of any specialty, including an endocrinologist. Factors were identified that could change the concentration of the biologically active fraction of the test substance, subsequently complicating the interpretation of laboratory results and making the right clinical decision. The literature describes a variety of circulating autoantibodies involved in binding to pituitary hormones (prolactin (PRL), thyroid-stimulating hormone (TSH), growth hormone, luteinizing, follicle-stimulating, and adrenocorticotropic hormones), hypothalamus (vasopressin and oxytocin), pancreas (insulin and glucagon) , parathyroid glands (parathyroid hormone), as well as with thyroid hormones. As a rule, the resulting macromolecules lead to an increase in laboratory parameters, in which the prevailing fraction of the hormone does not have biological activity, which determines the main problem of this phenomenon. The most common variants include immune complexes with PRL and TSH, causing the phenomena of macroprolactinemia and macrothyrotropinemia (macro-TSH-emia/macro-TSH), respectively. Most laboratory test systems used in clinical practice are capable of determining only the total amount of PRL and TSH. The presented clinical observation describes a combination of the phenomena of macro-TSH and macroprolactinemia in a patient with autoimmune thyroiditis (AIT) and vitiligo.

6469 Supplement Misadventures: A Case Of Acute Heart Failure, Cardiogenic Shock, And Hormonal Dysregulation Secondary To Surreptitious Use Of Multiple Hormonal Supplements

Abstract Disclosure: K.N. Grennan: None. S. Thota-Kammili: None. A.L. McKenna: None. C.G. Coyle: None. S.L. Samson: None. Introduction: Supplement misuse in the bodybuilding community is prevalent. With the availability of internet ordering and purchasing, patients have access to hormonal supplements without prescription or regulation. Here we present the case of a patient on self-administered hormonal supplements who presented in acute heart failure leading to cardiogenic shock in the setting of concurrent thyroid, adrenal, and gonadal axis dysfunction. Case Description: A 28-year-old male with no significant medical history was transferred to our hospital after presenting to an outside emergency room with dyspnea, cough, nausea, and a subjective fever. He developed acute hypoxic respiratory failure requiring intubation. Echocardiogram performed showed an ejection fraction (EF) of 10%. He was started on two vasopressors and methylprednisolone 1 g daily for two days, due to concern for myocarditis versus giant cell arteritis. Hormonal work-up showed TSH 0.02 mIU/L (normal range 0.3-4.2), free T4 0.4 ng/dL (0.9-1.7), total T3 48 ng/dL (80-200), FSH <0.3 IU/L (1.2-15.8), LH <0.2 IU/L (1.3-9.6), ACTH <5.0 pg/mL (7.2-63), cortisol 1.7 mcg/dL (2.5-12), estradiol 171 pg/mL (8.0-35), total testosterone 1730 ng/dL (240-950), and prolactin 47 ng/mL (4.0-15.2). He received 10 mg dexamethasone at the outside facility. A medication bag found by his family included online purchases of non-prescribed testosterone cypionate and enanthate, liothyronine, anastrozole, and clomiphene. None were medical grade. He was also taking the anabolic steroid clenbuterol for 3 days prior. Echocardiogram on day 3 of admission showed an improved EF of 36%. Cardiac magnetic resonance imaging (MRI) showed a papillary fibroelastoma and myocarditis. Patient was weaned off vasopressors and the ventilator. He was discharged on levothyroxine 50 mcg daily and hydrocortisone 10 mg twice daily for outpatient reassessment. Transesophageal echocardiogram confirmed diagnosis of papillary fibroelastoma. One month Endocrinology clinic follow-up showed no evidence of posterior pituitary, thyroid, or adrenal axis dysfunction or growth hormone excess, but he continued to have gonadal axis suppression with elevated prolactin and estradiol, the latter thought to be secondary to conversion from testosterone. Pituitary MRI showed no micro or macroadenoma. His EF recovered to 50%. He is pending surgical removal of the aortic valve fibroelastoma. Discussion: With hormonal supplements easily accessible online, it is important for physicians to counsel patients about the dangers of misuse. This case highlights a previously healthy 28-year-old man who presented in critical condition with cardiogenic shock and hypothalamic-pituitary axis dysfunction from supplements he purchased online. There should be targeted educational interventions regarding the harm of supplements aimed at the bodybuilding community to prevent similar cases. Presentation: 6/2/2024

Differential peptide-dependent regulation of growth hormone (GH): A comparative analysis in pituitary cultures of reptiles, birds, and mammals

Growth hormone (GH) is a pituitary protein that exerts pleiotropic roles in vertebrates. The mechanisms regulating GH synthesis and secretion are finely controlled by hypothalamic neuropeptides and other factors. These processes have been considerably studied in mammals but are still poorly understood in other groups. To better understand the pituitary GH regulation during vertebrate phylogeny, we compared the effects of incubating several peptides on cultures of ex-vivo pituitary fragments obtained from representative specimens of reptiles (iguana), birds (chicken) and mammals (rat). The peptides used were: growth hormone-releasing hormone (GHRH), thyrotropin-releasing hormone (TRH), pituitary adenylate cyclase-activating polypeptide (PACAP), ghrelin, gonadotropin-releasing hormone (GnRH), and somatostatin (SST). In rat pituitary cultures, GH secretion was stimulated by GHRH and TRH, while gh mRNA expression was increased by GHRH and PACAP. In the case of chicken pituitaries, GH release was promoted by GHRH, ghrelin, PACAP, and GnRH, although the latter two had a dual effect since at a shorter incubation time they decreased GH secretion; in turn, gh mRNA expression was significantly stimulated by TRH, PACAP, and GnRH. The most intense effects were observed in iguana pituitary cultures, where GH secretion was significantly augmented by GHRH, PACAP, TRH, ghrelin, and GnRH; while gh mRNA expression was stimulated by GHRH, TRH, and PACAP, but inhibited by ghrelin and SST. Also, in the three species, SST was able to block the GHRH-stimulated GH release. Furthermore, it was found that the expression of Pou1f1 mRNA was increased with greater potency by GHRH and PACAP in the iguana, than in chicken or rat pituitary cultures. Additionally, in-silico analysis of the gh gene promoter structures in the three species showed that the reptilian promoter has more Pit-1 consensus binding sites than their avian and mammalian counterparts. Taken together, results demonstrate that pituitary peptide-mediated GH regulatory mechanisms are differentially controlled along vertebrate evolution.

The somatotroph pituitary gland function in high-aged multimorbid hospitalized patients with IGF-I deficiency

PurposeIt is unclear whether the age-related decline in the somatotropic axis stems from a reduced growth hormone (GH) production in the pituitary gland, or from a peripheral origin akin to an acquired GH resistance. With the help of a GHRH/arginine test, high-aged multimorbid hospitalized patients with IGF-I deficiency are to be tested to determine whether there is primarily a pituitary GH deficiency in the sense of a somatopause.MethodsSeventeen multimorbid patients (eleven men and six women) with a mean age of 82 years, with IGF-I concentrations below two standard deviations of 30-year-old men and women were identified. Patients suffered from a variety of common age-related stable diseases including coronary artery disease, chronic liver or kidney disease, chronic heart failure as well as acute conditions e.g., urosepsis or endocarditis. To assess the somatotropic axis they underwent a GHRH/arginine test. Results were evaluated using descriptive statistics.ResultsIn average, the peak concentration of GH after stimulation was 14.8 µg/L with a range from 2.76 to 47.4 µg/L. Taking into account both, gender and BMI (with a mean of 26.5 kg/m²) for each participant, the pituitary gland was adequately stimulated in 16 out of the 17 patients. No patient reported common side effects related to the GHRH/arginine test.ConclusionThe somatotroph pituitary gland retains its secretory capacity in the advanced aged. Therefore, age does not seem to be the driving pacemaker for the functional decline of the somatotropic axis within the aged population.

Skin assessment in congenital untreated isolated GH deficiency.

The separation between the inside and outside through the skin was fundamental for the evolution of prevertebrates, which grow through extrapituitary circuits, to vertebrates, which grow through the somatotrophic axis, namely pituitary growth hormone (GH). and circulating IGF1.Individuals with untreated isolated growth hormone (GH) deficiency (IGHD) due to a mutation in the GH-releasing hormone receptor (GHRH) gene, residing in Itabaianinha, Brazil, are vulnerable to skin cancer and have reduced sweating. However other aspects of their skin physiology are still unknown. Our objectives were to evaluate the number of skin cancers, skin aging, and functional aspects of the skin in this IGHD cohort. Twenty-six IGHD individuals and 26 controls matched by age, sex, ethnicity, and occupation were submitted to a biochemical, dermatological and a functional skin assessment by the Multi Probe Adapter Cutometer® MPA 580. There was no difference in the number of skin cancers and in the degrees of photodamage between the groups. The melanin content in the forearm was similar between the groups but was lower in the buttocks (p = 0.005), as well as skin resistance (p < 0.0001) and elasticity (p = 0.003), lower in the IGHD. There was no difference in hydration and sebum content between the two groups. IGHD is apparently associated with a neutral profile in terms of skin cancer and photodamage, with similar melanin on the forearm and lower buttocks, lower skin resistance and elasticity, with hydration and sebum similar to controls.

Ectopic acromegaly due to bronchial neuroendocrine tumors: the first description in Russia of three clinical cases

Acromegaly is a neuroendocrine disorder caused by excessive production of growth hormone (GH). In the majority of cases the cause of acromegaly is a pituitary tumor producing GH. Cases of ectopic acromegaly are much rarer. Ectopic acromegaly occurs in cases of tumors which produce growth hormone-releasing hormone (GHRH) or extrapituitary tumors which produce GH. The main sources of excessive GHRH production are neuroendocrine tumors (NETs) of the lung or pancreas. Treatment of ectopic acromegaly consists of surgical removal of the source of GHRH hyperproduction and in cases where surgery is not an option, somatostatin analogues, pegvisomant, chemotherapy, immunotherapy or radiation therapy are used.In this article three cases of ectopic acromegaly due to GHRH-producing lung NETs are presented, each of them being notable for a number of features. In the first two cases, clinical symptoms were mild, besides in the second case ectopic acromegaly was accompanied by primary hyperparathyroidism. In the third case ectopic acromegaly was accompanied by pituitary macroadenoma, and after surgical removal of the lung NET remission of acromegaly was not achieved. In all three cases, lung NETs were detected incidentally on radiologic chest screening for other conditions.

The Treatment of Growth Disorders in Childhood and Adolescence.

3% of all children are unusually short, and 3% are unusually tall. New approaches have broadened the range of therapeutic options in treating growth disorders. This review is based on publications retrieved by a selective review of the literature and on the authors' clinical experience. Pituitary growth hormone deficiency is treated with recombinant growth hormone. Long-acting preparations of this type became available recently, but their long-term safety and efficacy are still unknown. Vosoritide, a CNP analogue, has also been approved for the treatment of achondroplasia, and severe primary deficiency of insulin-like growth factor 1 (IGF-1) can be treated with recombinant IGF-1. In the treatment of excessively tall stature, new information on the safety of growth-attenuating treatment and an altered perception of above-average height in society have led to a change in management. There are new options for the treatment of rare causes of short stature, while new information on the safety of treatment strategies for excessive tallness have led to a reconsideration of surgical intervention. There is insufficient evidence on the benefits and risks of supraphysiological GH therapy and of newer treatment options for which there are as yet no robust data on adult height. Therefore, before any treatment is provided, physicians should give patients and their families detailed information and discuss their expectations from treatment and the goals that treatment can be expected to achieve.

Clinical Characteristics and Management of Cosecreting Thyroid Stimulating Hormone or Prolactin Pituitary Growth Hormone Adenomas: A Case-Control Study

ObjectiveCosecreting thyroid stimulating hormone (TSH) or prolactin (PRL) in patients with pituitary growth hormone (GH) adenomas has been rarely reported. Our study aimed to elucidate their clinical characteristics. MethodsWe retrospectively collected data of 22 cases of cosecreting GH and TSH pituitary adenomas [(GH+TSH)oma] and 10 cases of cosecreting GH and PRL pituitary adenomas [(GH+PRL)oma] from Beijing Tiantan Hospital, Capital Medical University between January 2009 and January 2023. The clinical manifestation, preoperative hormone levels, imaging features, pathologic characteristics, and biochemical remission rates were compared among 335 patients with solo-secreting GH adenomas (GHoma) and 49 patients with solo-secreting TSH adenoma (TSHoma). Patients with (GH+TSH)oma and (GH+PRL)oma were grouped according to biochemical remission to explore the risk factors leading to biochemical nonremission. ResultsCosecreting pituitary GH adenomas had various clinical manifestations and a larger tumor volume and were more likely to invade the cavernous sinus bilaterally and compress the optic chiasm. GH and TSH levels were lower in (GH+TSH)oma than in GHoma or TSHoma. Solo part remission was observed both in (GH+TSH)oma and (GH+PRL)oma. Cavernous sinus invasion was an independent risk factor for biochemical nonremission in patients with (GH+TSH)oma and (GH+PRL)oma. ConclusionsThe clinical manifestation of (GH+TSH)oma and (GH+PRL)oma may be atypical. When screening for pituitary adenomas, a comprehensive evaluation of all pituitary target gland hormones is needed. Cosecreting pituitary GH adenomas are more aggressive and surgery is often unable to completely remove the tumor, requiring pharmacologic or radiological treatment if necessary. Clinicians should give high priority to biochemical remission, although solo part remission may occur.

Iatrogenic Alzheimer’s disease in recipients of cadaveric pituitary-derived growth hormone

Alzheimer’s disease (AD) is characterized pathologically by amyloid-beta (Aβ) deposition in brain parenchyma and blood vessels (as cerebral amyloid angiopathy (CAA)) and by neurofibrillary tangles of hyperphosphorylated tau. Compelling genetic and biomarker evidence supports Aβ as the root cause of AD. We previously reported human transmission of Aβ pathology and CAA in relatively young adults who had died of iatrogenic Creutzfeldt–Jakob disease (iCJD) after childhood treatment with cadaver-derived pituitary growth hormone (c-hGH) contaminated with both CJD prions and Aβ seeds. This raised the possibility that c-hGH recipients who did not die from iCJD may eventually develop AD. Here we describe recipients who developed dementia and biomarker changes within the phenotypic spectrum of AD, suggesting that AD, like CJD, has environmentally acquired (iatrogenic) forms as well as late-onset sporadic and early-onset inherited forms. Although iatrogenic AD may be rare, and there is no suggestion that Aβ can be transmitted between individuals in activities of daily life, its recognition emphasizes the need to review measures to prevent accidental transmissions via other medical and surgical procedures. As propagating Aβ assemblies may exhibit structural diversity akin to conventional prions, it is possible that therapeutic strategies targeting disease-related assemblies may lead to selection of minor components and development of resistance.

Connexin 36 Mediated Intercellular Endoplasmic Reticulum Stress Transmission Induces SSTA Resistance in Growth Hormone Pituitary Adenoma.

Somatostatin analogues (SSTA) are first-line pharmacological treatment choice for acromegaly, which received satisfying tumor shrinkage and normalization of growth hormone. However, there are still patients unresponsive to SSTA, and the underline mechanism remains unknown. Besides, there is no evidence regarding the role of endoplasmic reticulum stress (ERS) and its transmission in SSTA resistance, which also require investigation. Primary growth hormone adenoma cells and cell lines were treated with SSTA; autophagy double-labeled LC3 (mRFP-GFP) adenovirus transfection, flow cytometry sorting, western blotting, calcium imaging as well as immunofluorescence staining were used to determine ERS and autophagy signal transmission; xenograft and syngeneic tumor in vivo model were exploited to confirm the ERS signal transmission mediated effect. Our results revealed that SSTA induces ERS in pituitary growth hormone (GH) adenoma cells. The ERS signals can be intercellularly transmitted, leading to less responsible to SSTA treatment. Moreover, SSTA stimulates inositol triphosphate (IP3) elevation, mediating ERS intercellular transfer. In addition, connexin 36 tunnels ERS transmission, and its blocker, Quinine, exhibits a synergistic effect with SSTA treating GH adenoma. Our study provided insight into ERS intercellular transmission mediated SSTA resistance, which could be translated into clinical usage to improve SSTA efficiency in GH adenoma treatment.

Corticosteroid-Binding Globulin (SERPINA6) Consolidates Sexual Dimorphism of Adult Rat Liver.

Produced by the liver, corticosteroid-binding globulin (CBG) regulates the plasma distribution and actions of glucocorticoids. A sex difference in pituitary growth hormone secretion patterns established during puberty in rats results in increased hepatic CBG production and 2-fold higher plasma corticosterone levels in females. Glucocorticoids control hepatic development and metabolic activities, and we have therefore examined how disrupting the SerpinA6 gene encoding CBG influences plasma corticosterone dynamics, as well as liver gene expression in male and female rats before and after puberty. Comparisons of corticosterone plasma clearance and hepatic uptake in adult rats, with or without CBG, indicated that CBG limits corticosterone clearance by reducing its hepatic uptake. Hepatic transcriptomic profiling revealed minor sex differences (207 differentially expressed genes) and minimal effect of CBG deficiency in 30-day-old rats before puberty. While liver transcriptomes in 60-day-old males lacking CBG remained essentially unchanged, 2710 genes were differentially expressed in wild-type female vs male livers at this age. Importantly, ∼10% of these genes lost their sexually dimorphic expression in adult females lacking CBG, including those related to cholesterol biosynthesis, inflammation, and lipid and amino acid catabolism. Another 203 genes were altered by the loss of CBG specifically in adult females, including those related to xenobiotic metabolism, circadian rhythm, and gluconeogenesis. Our findings reveal that CBG consolidates the sexual dimorphism of the rat liver initiated by sex differences in growth hormone secretion patterns and provide insight into how CBG deficiencies are linked to glucocorticoid-dependent diseases.

Anomalies du récepteur de l’hormone de croissance hypophysaire et de son effecteur de l’axe somatotrope, l’Insulin-Like Growth Factor I

Postnatal statural growth is under the hormonal control of the somatotropic axis: hypothalamus-pituitary-liver-bone. Numerous gene abnormalities have been described, located at the hypothalamus and especially at the pituitary levels. Rarer damages are located downstream at the level of the pituitary growth hormone (GH) receptor, as in Laron's syndrome or in post-receptor signaling, Stat5b or the terminal effector of growth, the Insulin-Like Growth Factor I (IGF I). For several decades now, these severe statural growth retardations can benefit from recombinant IGF I treatment, with variable efficacy depending on the genetic abnormality.

THU043 Single-cell Transcriptomics Show Sex-specific Responses To A High Fat Diet, Under Thermoneutral Conditions, Pointing To Reduced Pituitary Plasticity

Abstract Disclosure: T.K. Miles: None. A.N. Lagasse: None. A.K. Odle: None. S.S. Lira: None. M.M. Syed: None. N. Akhter: None. M.C. MacNicol: None. A.M. MacNicol: None. G.V. Childs: None. Hyperinsulinemia caused by a high fat diet (HFD) directly suppressed pituitary growth hormone (Gh) and growth hormone releasing hormone receptor (Ghrhr) mRNAs (Luque and Kineman, 2006). To study the broader impact of a HFD, we exposed 3 groups of FVB.129P mice to 60% HFD for 10 or 15 wks at thermoneutrality (TN) (30 C), or 15 wks at room temperature (RT). Pituitary transcript expression was analyzed with single-cell RNA-seq. HFD-fed mice gained &amp;gt;20 g by 12 wks, showing increased serum leptin (1.8-2X), insulin (2-8X) and IL-6 (4-6X), decreased glucose clearance after a glucose challenge and decreased respiratory quotient indicating fat burning. Activity was unaffected by HFD. Rank plot analyses showed reduced amplitude GH pulses in HFD females fed at RT (15 wks), but not in mice fed at TN. Serum levels of other pituitary hormones were unaffected in HFD females. In HFD males, only serum TSH was elevated significantly (1.8X, 15 wks, TN). Analysis of the scRNA-seq data detected separate clusters representing each cell type. Two multihormonal cell clusters evident in control females mostly disappeared following HFD (15 wks, RT). At the threshold cutoff of avg Log2FC±0.5 with adj p&amp;lt;0.05, female somatotrope clusters showed reduced Pomc, Cga, and ribosomal proteins. Female lactotrope clusters exhibited decreased Gh mRNA (avg Log2FC -1.8 or -2.5) and galanin at 10 wks (TN). At 15 wks (TN), lactotrope clusters showed significant changes in 46 transcripts including reductions in Prl, 29 ribosomal proteins, galanin, and 3 transcriptional regulators. Notably, this cluster showed an increase in synaptotagmin-4 (Syt4), which is also elevated in oxytocin neurons following a HFD. Stem cell clusters in females were strongly impacted by HFD after 15 weeks (TN) with 94 reduced transcripts of which 48 were involved in cytoplasmic translation and ribosome biogenesis and &amp;gt;20 were involved with signaling and cell differentiation. In males, whereas changes in most clusters fell below the threshold cutoffs, stem cell clusters had 13 reduced transcripts after 10 or 15 weeks, most of which involved immune system processes including defense responses and antigen processing and presentation. The GH deficiency in mice fed under thermoneutral conditions was not as severe as that reported by Luque and Kineman, perhaps due to differences in strain, sex, and/or the environmental temperature. The reduced expression of multihormonal clusters, Gh by lactotropes and corticotropes, and Cga and Pomc by somatotropes suggests that HFD may reduce plasticity and activity of progenitor cells in the pituitary. The changes in lactotropes and somatotropes also indicate that HFD may compromise ribosome function and cytoplasmic translation. The reduced transcriptome in stem cells in both males and females suggests HFD interference with cell differentiation and pituitary plasticity as well as dysfunctional immune defense responses. Presentation: Thursday, June 15, 2023

THU046 Repeated Treatment With AZP-3813, A Bicyclic, 16-Amino Acid Peptide Antagonist Of The Human Growth Hormone Receptor, Induces Enhanced Suppression Of IGF1 In Beagle Dogs

Abstract Disclosure: G. Ravel: None. C. Chalmey: None. C. Berardet: None. D. Duracher: None. H. Kurasaki: None. T. Tomiyama: None. P. Reid: None. M.D. Culler: None. Medical treatment of acromegaly is based on either suppressing pituitary growth hormone (GH) secretion or inhibiting GH action by preventing interaction with its receptor in order to suppress the elevated levels of insulin-like growth factor 1 (IGF1). AZP-3813 is a 16-amino acid, bicyclic peptide antagonist of the GH receptor (GHR) derived from peptide sequences discovered using a unique, cell-free in vitro transcription-translation system screened against the human GHR, and optimized by rational design to increase binding affinity, solubility and half-life. The KD of AZP-3813 for the human GHR is 1.9nM. In previous studies, AZP-3813 was demonstrated to suppress IGF1 secretion in juvenile rats in a dose-related manner, and to maintain IGF1 suppression when given daily for extended periods. Recently, we demonstrated that AZP-3813 is also very effective in suppressing IGF1 in normal Beagle dogs. Dogs receiving a single 0.1, 1 and 10 mg/kg subcutaneous injection of AZP-3813 responded with a dose-related 2.2 + 7.1, 21.4 + 2.7 and 27.8 + 1.5% decrease in IGF1 after 24 hours, respectively, and the decrease in IGF1 attained with a single 10 mg/kg dose was maintained for over 72 hours. The relatively small further increase in IGF1 suppression with 10 versus 1 mg/kg suggests that 10 mg/kg AZP-3813 may induce near maximal GHR antagonism. To examine the effect of repeated and higher dose treatment of dogs with AZP-3813, young adult, non-fasted, Beagle dogs were injected subcutaneously at rotated dorsal sites with AZP-3813 at doses of 10, 30 or 60 mg/kg (n=2, one male and one female) daily for seven days. Blood samples, collected prior to dosing to establish baseline IGF1 levels and 24 hour after the final, seventh AZP-3813 injection, were assayed for total IGF1 content by radioimmunoassay. Baseline IGF1 levels were lower in the female dogs (136.7 + 36.1 ng/ml) than in the male dogs (197.0 + 11.3 ng/ml); however, the percent IGF1 suppression resulting from AZP-3813 treatment was similar for both sexes. AZP-3813, injected for seven days at 10, 30 and 60 mg/kg, induced highly significant 69.0 + 4.0, 70.5 + 9.5 and 75.0 + 1.0% decreases in IGF1, respectively. The similar magnitude of IGF1 suppression attained with the three doses of AZP-3813 implies that maximal GH antagonism is essentially achieved with the 10 mg/kg dose. The substantial increase in IGF1 suppression achieved by repeated 10 mg/kg injection of AZP-3813, compared to the previously observed suppression after a single 10 mg/kg injection, likely represents compound accumulation (under investigation) as well as a progressive effect of maximal GH antagonism on IGF1 production. These results demonstrate that the potent GHR antagonist activity of AZP-3813 translates to a highly effective suppression of IGF1 in normal dogs and further support the development of AZP-3813 as a potential therapy for acromegaly. Presentation: Thursday, June 15, 2023

GHRH Neurons from the Ventromedial Hypothalamic Nucleus Provide Dynamic and Sex-Specific Input to the Brain Glucose-Regulatory Network.

The ventromedial hypothalamic nucleus (VMN) controls glucose counter-regulation, including pituitary growth hormone (GH) secretion. VMN neurons that express the transcription factor steroidogenic factor-1/NR5A1 (SF-1) participate in glucose homeostasis. Research utilized in vivo gene knockdown tools to determine if VMN growth hormone-releasing hormone (Ghrh) regulates hypoglycemic patterns of glucagon, corticosterone, and GH outflow according to sex. Intra-VMN Ghrh siRNA administration blunted hypoglycemic hypercorticosteronemia in each sex, but abolished elevated GH release in males only. Single-cell multiplex qPCR showed that dorsomedial VMN (VMNdm) Ghrh neurons express mRNAs encoding Ghrh, SF-1, and protein markers for glucose-inhibitory (γ-aminobutyric acid) or -stimulatory (nitric oxide; glutamate) neurotransmitters. Hypoglycemia decreased glutamate decarboxylase67 (GAD67) transcripts in male, not female VMNdm Ghrh/SF-1 neurons, a response that was refractory to Ghrh siRNA. Ghrh gene knockdown prevented, in each sex, hypoglycemic down-regulation of Ghrh/SF-1 nerve cell GAD65 transcription. Ghrh siRNA amplified hypoglycemia-associated up-regulation of Ghrh/SF-1 neuron nitric oxide synthase mRNA in male and female, without affecting glutaminase gene expression. Ghrh gene knockdown altered Ghrh/SF-1 neuron estrogen receptor-alpha (ERα) and ER-beta transcripts in hypoglycemic male, not female rats, but up-regulated GPR81 lactate receptor mRNA in both sexes. Outcomes infer that VMNdm Ghrh/SF-1 neurons may be an effector of SF-1 control of counter-regulation, and document Ghrh modulation of hypoglycemic patterns of glucose-regulatory neurotransmitter along with estradiol and lactate receptor gene transcription in these cells. Co-transmission of glucose-inhibitory and -stimulatory neurochemicals of diverse chemical structure, spatial, and temporal profiles may enable VMNdm Ghrh neurons to provide complex dynamic, sex-specific input to the brain glucose-regulatory network.

Long acting growth hormone (LAGH), an update.

In 1957, Maurice Raben at Yale was able to isolate and purify growth hormone from cadaveric pituitary glands. Pituitary growth hormone was the only way to treat children with growth hormone (GH) deficiency, until 1985 when recombinant GH became available for daily subcutaneous injection. For many years, the pediatric endocrine community longed for a long-acting recombinant GH formulation that would decrease the inconvenience of daily injections. Several mechanisms were employed to develop a GH that is rapidly absorbed into the blood stream after subcutaneous injection, but provides slow removal from the circulatory system to potentially optimize patient adherence to GH therapy. Four long-acting growth hormones are currently available in the world, or are close to regulatory approval. They are: (1) Pegylated formulations, (2) Prodrug formulations which are converted into active drug, (3) Nonvalent transient albumin binding GH compounds and (4) GH fusion proteins where a protein si fused with GH. All four formulations have undergone detailed phase 3 studies and were found to show non-inferiority in these clinical studies. All four demonstrate a safety and tolerability profile that is comparable to that of daily somatropin with an excellent adherence profile.

Production and engineering of nanobody-based quenchbody sensors for detecting recombinant human growth hormone and its isoforms.

Due to athletes' misuse of recombinant human growth hormone (rhGH) for performance improvement, the World Anti-Doping Agency has designated rhGH as a prohibited substance. This study focuses on the development and improvement of a simple and fast rhGH detection method using a fluorescence-incorporated antibody sensor "Quenchbody (Q-body)" that activates upon antigen binding. Camelid-derived nanobodies were used to produce stable Q-bodies that withstand high temperatures and pH levels. Notably, pituitary human growth hormone (phGH) comprises two major isoforms, namely 22 and 20 kDa GH, which exist in a specific ratio, and the rhGH variant shares the same sequence as the 22 kDa GH isoform. Therefore, we aimed to discriminate rhGH abuse by analyzing its specific isoform ratio. Two nanobodies, NbPit (recognizing phGH) and NbRec (preferentially recognizing 22 kDa rhGH), were used to develop the Q-bodies. Nanobody production in Escherichia coli involved the utilization of a vector containing 6xHis-tag, and Q-bodies were obtained using a maleimide-thiol reaction between the N-terminal of the cysteine tag and a fluorescent dye. The addition of tryptophan residue through antibody engineering resulted in increased fluorescence intensity (FI) (from 2.58-fold to 3.04-fold). The limit of detection (LOD) was determined using a fluorescence response, with TAMRA-labeled NbRec successfully detecting 6.38 ng/ml of 22 kDa rhGH while unable to detect 20 kDa GH. However, ATTO520-labeled NbPit detected 7.00 ng/ml of 20 kDa GH and 2.20 ng/ml 22 kDa rhGH. Q-bodies successfully detected changes in the GH concentration ratio from 10 to 40 ng/ml in human serum within 10 min without requiring specialized equipment and kits. Overall, these findings have potential applications in the field of anti-doping measures and can contribute to improved monitoring and enforcement of rhGH misuse, ultimately enhancing fairness and integrity in competitive sports.

Role and molecular mechanism of ghrelin in degenerative musculoskeletal disorders.

Ghrelin is a brain-gut peptide, and the first 28-peptide that was found in the gastric mucosa. It has a growth hormone (GH)-releasing hormone-like effect and can potently promote the release of GH from pituitary GH cells; however, it is unable to stimulate GH synthesis. Therefore, ghrelin is believed to play a role in promoting bone growth and development. The correlation between ghrelin and some degenerative diseases of the musculoskeletal system has been reported recently, and ghrelin may be one of the factors influencing degenerative pathologies, such as osteoporosis, osteoarthritis, sarcopenia and intervertebral disc degeneration. With population ageing, the risk of health problems caused by degenerative diseases of the musculoskeletal system gradually increases. In this article, the roles of ghrelin in musculoskeletal disorders are summarized to reveal the potential effects of ghrelin as a key target in the treatment of related bone and muscle diseases and the need for further research.

Morphological and Functional Changes of Pituitary GH and PRL Cells Following Prolonged Exposure of Female Rats to Constant Light

Abstract Light regulates numerous physiological functions including secretion of different hormones. Our aim was to determine morphological and functional changes of the pituitary growth hormone (GH) and prolactin (PRL) producing cells in female rats exposed to constant light regime from the peripubertal to adult period of life. Starting from the thirtieth postnatal day, female Wistar rats were exposed to constant light (600 lx) for the following 95 days. Controls were maintained under the regular laboratory lighting conditions. The GH and PRL cells were immunohistochemically visualized. Changes in cell volumes and volume densities were evaluated by stereology. Concentrations of PRL and GH in circulation were also determined. We detected significant decrease of the GH cell volume and volume density, followed by reduced the GH blood concentration in comparison to the controls. In contrast, PRL cells were larger in size and their volume density was significantly increased when compared to the controls. Accordingly, PRL concentration was elevated. It can be concluded that exposure of female rats to constant light regime, from peripubertal to adult period of life, causes inhibition of the pituitary GH and stimulation of PRL cells.

Prevalence of refractoriness when testing growth hormone levels in children

ObjectiveLate night spontaneous growth hormone (GH) pulses may influence the pituitary GH response to provocation tests. We evaluated GH response during arginine-insulin-tolerance test (AITT) after a GH peak during a short spontaneous nocturnal profile (SSNP) in children with short stature or low growth velocity. DesignUsing SSNP and subsequent AITT, we examined 257 children 4–18 years old (138 (53.7%) males) recruited from three hospitals. Medical records were reviewed retrospectively. Refractory children were defined as a GH peak ≥7 μg/L during SSNP but no GH peak ≥7 μg/L during AITT. ResultsIn total, 201/257 children had a GH peak ≥7 μg/L at SSNP and/or AITT. Of these, 21.9% were refractory. The proportion of males (p = 0.033) and body mass index (BMI) standard deviation score (SDS) (p = 0.037) were higher in the refractory group than in children with a GH peak ≥7 μg/L during AITT. The median period between last GH peak ≥7 μg/L during SSNP and GHmax at AITT was 210 (30–390) minutes. The GHmax at AITT occurred 30 min earlier for children without a peak ≥7 μg/L during the SSNP (p = 0.004). The number of refractoriness differed somewhat between the hospitals (p = 0.025). ConclusionsMany children with short stature were refractory at testing; among them we found few clinical characteristics. Refractoriness might be influenced by some differences in procedure, but needs to be considered when evaluating GH response in children.