Growth Hormone Release Research Articles

117 Improved Growth Performance in the F1 Heterozygous Generation of an SSTR2 Knockout Model in Swine

Abstract Targeted genetic alteration provides opportunities for rapid genetic improvement in resilience, welfare and production traits. Somatostatin (SST) acts via negative feedback to regulate growth hormone (GH) activity by antagonizing GH releasing hormone via SST receptors (SSTR) located in the anterior pituitary. Our objective was to reduce the negative effect of SST in the anterior pituitary on protein accretion by reducing the number of functional copies of SSTR2 using the CRISPR/Cas9 system. We hypothesized that a reduction or elimination of SSTR2 would lead to improved growth performance. To test this hypothesis, three commercial gilts were bred with semen from a founder boar in a compound heterozygous state at the SSTR2 locus with a 1bp deletion in one allele resulting in a premature stop codon and a 3bp deletion in the other allele resulting in the loss of a single amino acid predicted to remain functional after translation. Three litters of F1 offspring were produced (n = 46) and all piglets were confirmed to be heterozygous at the SSTR2 locus with one wild type allele and the other possessing either the 1bp deletion (n = 22) or the 3bp (n = 2 4) deletion. No differences (P > 0.43; n=46) in body weight (1.27±0.03 kg) across comparisons were observed at birth. At weaning (n = 36), males (6.19±0.20 kg) were heavier (P = 0.007) than females (5.41±0.19 kg), and piglets possessing a 1bp deletion (6.00±0.20 kg) were numerically heavier (P = 0.14) than 3bp deletion pigs (5.59±0.18 kg). This observation was more pronounced in males at weaning, where the males with the 1bp deletion were 13% heavier (P = 0.058) than those with the 3bp deletion. These data suggest that altering SSTR2 may be a viable genetic advancement strategy to improve growth performance in pigs. This project was supported by the Lloyd L. Anderson Professorship in Physiology at Iowa State University.

Acromegaly in a Young Women With Pituitary Hyperplasia Secondary to a Neuroendocrine Tumor

Acromegaly is rarely due to an excess of the GH-releasing hormone (GHRH) and pituitary hyperplasia on histology should alert to its presence. Clinical Case: A 35-year-old was referred to surgery with a confirmed diagnosis of symptomatic acromegaly. Her GH failed to suppress during an oral glucose tolerance test (OGTT), her IGF-1 and prolactin was high. Her serum calcium was normal and her chromogranin B was high. MRI scan suggested microadenoma. Her surgery was deferred because of Covid 19, and she was treated with somatostatin analog (SSA). She finally had surgery in July. The histology and immunocytochemistry suggested pituitary hyperplasia with diffuse positivity for chromogranin and synaptophysin. GH was positive in the majority of the cells with many cells positive for Prolactin and ACTH. FSH and LH were positive in scattered cells with patchy positivity of TSH. A solitary nodule was noted in her neck during an examination. We arranged to look for conditions associated with pituitary hyperplasia resulting in GHRH production, including the genetic tests for inherited conditions. Her calcitonin level was normal. She had an ultrasound scan guided fine needle aspiration of the thyroid nodule, this showed Thy3f oncocytic nodule with no features of medullary thyroid carcinoma. She had an NMGa68DOTATATE whole body PET CTand the scan showed a large DOTATAE avid mass from the right adrenal gland compatible with Pheochromocytoma. Her 24 hours total urinary metadrenaline and normetadrenalin was high. Her genetic test for MEN1, CDKN1B, and MEN2 are negative. We have requested the GHRH measurement. After a pituitary surgery, her GH suppressed adequately on OGTT. Her IGF-1 and prolactin is low and her hypogonadism is resolved. Conclusion: Excess production GHRH can result from neuroendocrine tumors of the lung, pancreas, thyroid (medullary thyroid cancer), or pheochromocytomas and hypothalamic gangliocytomas.Several familial syndromes, multiple endocrine neoplasia type 1 (MEN1) and 4 (MEN4), familial isolated pituitary adenoma (FIPA), Carney complex, and sporadic germline mosaic disorder McCune-Albright disease predispose to pituitary hyperplasia. GHRH acromegaly should be suspected in a patient with biochemical/clinical features of acromegaly in the presence of co-existing neuroendocrine tumors when there is diffuse pituitary enlargement on imaging or resolution of acromegaly after the surgical resection of the primary neuroendocrine tumour or persistent acromegaly after surgery if there is histological evidence of somatotroph hyperplasia.

ARCGHR Neurons Regulate Muscle Glucose Uptake.

The growth hormone receptor (GHR) is expressed in brain regions that are known to participate in the regulation of energy homeostasis and glucose metabolism. We generated a novel transgenic mouse line (GHRcre) to characterize GHR-expressing neurons specifically in the arcuate nucleus of the hypothalamus (ARC). Here, we demonstrate that ARCGHR+ neurons are co-localized with agouti-related peptide (AgRP), growth hormone releasing hormone (GHRH), and somatostatin neurons, which are activated by GH stimulation. Using the designer receptors exclusively activated by designer drugs (DREADD) technique to control the ARCGHR+ neuronal activity, we demonstrate that the activation of ARCGHR+ neurons elevates a respiratory exchange ratio (RER) under both fed and fasted conditions. However, while the activation of ARCGHR+ promotes feeding, under fasting conditions, the activation of ARCGHR+ neurons promotes glucose over fat utilization in the body. This effect was accompanied by significant improvements in glucose tolerance, and was specific to GHR+ versus GHRH+ neurons. The activation of ARCGHR+ neurons increased glucose turnover and whole-body glycolysis, as revealed by hyperinsulinemic-euglycemic clamp studies. Remarkably, the increased insulin sensitivity upon the activation of ARCGHR+ neurons was tissue-specific, as the insulin-stimulated glucose uptake was specifically elevated in the skeletal muscle, in parallel with the increased expression of muscle glycolytic genes. Overall, our results identify the GHR-expressing neuronal population in the ARC as a major regulator of glycolysis and muscle insulin sensitivity in vivo.

Interrupted IGF-1 Feedback in GHRH Neurons and Somatotrophs Results in Impaired Weight Gain and Increased Energy Expenditure

Growth hormone (GH) expression and release are thought to be primarily regulated by the counter-regulatory effects of growth hormone-releasing hormone (GHRH) and somatostatin (SST). Several reports generated in our lab and others suggest that there are other factors that regulate GH production, such as insulin-like growth factor 1 (IGF-I). Using GH-Cre recombinase targeting of the somatotroph-specific IGF-1R knockout (SIGFRKO) mouse model, we have previously demonstrated the role of IGF-1 signaling in negative feedback regulation of GH production. This model, however, presented with an incomplete phenotype, suggesting additional regulatory pathways in the hypothalamus. To provide insight into this mechanism, we have developed new transgenic mouse models that maintain the integrity of the hypothalamic-pituitary GH axis, with the single exception of IGF-IR deficiency in both hypothalamic GHRH neurons and somatotroph cells, termed GHRH-somatotroph IGF-1R knockout (G-SIFGRKO). Axiological assessments showed normal linear growth until week 14 of age, both male and female G-SIFGRKO mice presented with a significant reduction in growth velocity compared to control animals. Indirect calorimetry assessment performed at 12–14 weeks of age demonstrated that G-SIFGRKO mice had higher volume O2 consumption and lower volume CO2 production associated with increased energy expenditure than controls. The calculated respiratory exchange ratio was significantly reduced in G-SIFGRKO mice with no changes observed in either ambulatory or total activity. Furthermore, glucose and insulin tolerance tests showed no differences in glucose metabolism between G-SIFGRKO and controls. Collectively, these data provide further confirmation of the combinatorial role of IGF-1 signaling in regulating GH production and, for the first time, highlight a new GHRH-IGF-1R mediated pathway to regulate body growth and energy balance. Targeting this pathway has the potential to lead to a better understanding of the intersection between growth and metabolism and therapeutic approaches for obesity.

Growth Hormone Releasing Hormone Reduces Plasma Markers of Immune Activation and Hepatic Immune Pathways in Nonalcoholic Fatty Liver Disease

Introduction: The GH/IGF-1 axis affects multiple metabolic pathways, and animal models demonstrate that it also modulates immune function. Little is known, however, regarding effects of augmenting GH secretion on immune function in humans. This study used proteomics and gene set enrichment analysis to assess effects of a GH releasing hormone (GHRH) analog, tesamorelin, on circulating immune markers and immune-related gene pathways in the liver in people with HIV (PWH) and NAFLD. We hypothesized that tesamorelin would decrease circulating markers of immune activation in conjunction with previously reported reductions in visceral fat and hepatic triglyceride. Methods: 92 biomarkers associated with immune function (Olink Immuno-Oncology panel) were measured in plasma samples from 61 PWH with NAFLD who participated in a double-blind, randomized, 12-month trial of tesamorelin versus identical placebo. Proteins differentially altered by tesamorelin at a false discovery rate < 0.1 were considered significantly changed. Gene set enrichment analysis targeted to immune pathways was subsequently performed on liver tissue from serial biopsies. Results: Compared to placebo, tesamorelin decreased circulating concentrations of 13 proteins, including four chemokines (C-C Motif Chemokine Ligands 3 [CCL3, effect size -0.38 Log2 fold change], 4 [CCL4, -0.36 Log2 fold change], and 13 [CCL13 or MCP4, -0.42 Log2 fold change] and interleukin-8 [-0.50 Log2 fold change]), two cytokines (interleukin-10 [-0.32 Log2 fold change] and cytokine stimulating factor 1 [-0.22 Log2 fold change]), and four T-cell associated molecules (CD8A [-0.37 Log2 fold change], Cytotoxic And Regulatory T Cell Molecule [CRTAM, -0.47 Log2 fold change], granzyme A [-0.53 Log2 fold change], and adhesion G protein-coupled receptor G1 [ADGRG1, -0.54 Log2 fold change]), as well as arginase-1 [-0.95 Log2 fold change], galectin-9 [-0.26 Log2 fold change], and hepatocyte growth factor [-0.30 Log2 fold change]. No proteins in the panel were significantly increased by tesamorelin. Network analysis indicated close interaction among the gene pathways responsible for the reduced proteins, with imputational analyses suggesting down regulation of a closely related cluster of immune pathways. Targeted transcriptomics using tissue from liver biopsy confirmed an end-organ signal of down-regulated immune pathways, including pathways involved in antigen presentation, complement activation, toll like receptor and inflammatory signaling, and T-cell activation. Conclusions: Long-term treatment with tesamorelin decreased circulating markers of T-cell and monocyte/macrophage activity, with corresponding downregulation of immune pathways in the liver. These findings suggest that augmenting pulsatile GH may ameliorate immune activation in a population with metabolic dysregulation and systemic inflammation.

Papillary Thyroid Carcinoma and Cushing’s Disease: A Rare Association With Multiple Endocrine Neoplasia Type 1

Introduction: Multiple Endocrine Neoplasia type 1 (MEN1) is characterized by tumours of the parathyroid glands, neuroendocrine pancreatic tumour (PNET), and anterior pituitary. Studies suggest that MEN1 gen is not etiologically related to the oncogenesis of the papillary thyroid carcinoma (PTC). Expression of menin is preserved in human normal thyroid tissue and THc. Papillary thyroid carcinoma (PTC) combined with multiple endocrine neoplasia type 1 is a rare association. Cushing Syndrome (CS) is another rare associated condition with MEN-1. In patients with MEN1, CS can result from pituitary, adrenal, or other endocrine tumours. In large series of MEN-1 CS has low frequency (0.5%) or not described. Clinical Case: A.M.F.A, 49 years, female. In 2007, cytological study of thyroid nodules resulted in PTC, underwent total thyroidectomy. Anatomopathological (AP) confirmed PTC. She was followed with an excellent response to therapy. In 2018, abdominal ultrasound due to epigastric pain showed pancreatic lesion. MRI confirmed lesion in the head and body of the pancreas of 8.2cm. She underwent total gastroduodenopacreatectomy (TGDP), AP showed a well-differentiated PNET (KI67: 2%). Before TGDP, tests for MEN-1 were collected: IGF-1 of 450 ng/ml (RV for age: 90-249 ng/ml); calcium: 1,46 nmol/l (RV: 1,12-1,40), PTH: 91,7 pg/ml (RV: 15-65), prolactin 13,3 ng/ml (RV: 5-23), gastrin 22pg/ml (RV 13-115), and late night salivary cortisol (LNSC): 8,3 nmol/l (RV <7,6). Pituitary MRI showed a 0.5cm intrasellar nodule. Genetic study revealed c654 + 1G>T mutation in heterozygosity. O3 family members had the same mutation. To investigate hypercortisolism, it was made basal ACTH (56,1 pg/ml (VR 46 pg/ml), urine free cortisol (UFC) of 261,0 mcg/24h, 1mg DST of 15,2 mcg/dl (RV <1,8), basal cortisol of 16,5 mcg/dl and 8mg DST of 13,7 mcg/dl (not 50% suppressing of basal value). Another measurement of IGF-1 (after the PNET surgery) was normal. A petrosal venous sinus catheterization (PVSC) was made, which was compatible with Cushing’s disease (CD). She had brittle hair, facial plethora, proximal muscle weakness and easily bruising, without other clinical CS aspects. Treatment with ketoconazole was initiated and she was referred to transesphenoidal surgery. Conclusion: Patient had two rare presentation of MEN1, first manifestation was PTC. PNET and CD was diagnosed 11 years late during clinical follow up. In this patient, MEN1 syndrome may have predisposed the patient to developing PTC. Currently, little is known about the prevalence of THc in MEN1 and it is unclear whether tumorigenesis is related. Further studies and additional case reports are required to clarify this connection. Also, we observed IGF-1 value normalized after TGDP, so it could be caused by a functional PNET. Rare causes of acromegaly are excess secretion of GH-releasing hormone (GHRH) by hypothalamic tumours, and ectopic GHRH or GH secretion by NET.

The Links of Ghrelin to Incretins, Insulin, Glucagon, and Leptin After Bariatric Surgery.

Type 2 diabetes mellitus (T2DM) is one of the most prominent and socially significant problems. The present study aimed to identify the mechanisms of interaction of critical regulators of carbohydrate metabolism using bioinformatics and experimental methods and to assess their influence on the development of T2DM. We conducted an in silico search for the relationship of hormones and adipokines and performed functional annotation of the receptors for ghrelin and incretins. Hormones and adipokines were assessed in the plasma of obese patients with and without T2DM as well as after laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB) surgeries. Incretin- and ghrelin-associated functions and metabolic processes were discovered. Low ghrelin levels were observed in obese patients without T2DM compared with healthy volunteers and the other groups. The highest ghrelin levels were observed in obese patients with T2DM. This defense mechanism against insulin resistance could be realized through the receptors G-protein-coupled receptor (GPCR), growth hormone secretagogue receptor (GHSR), and growth hormone-releasing hormone receptor (GHRHR). These receptors are associated with proliferative, inflammatory, and neurohumoral signaling pathways and regulate responses to nutrient intake. Signaling through the GPCR class unites ghrelin, glucagon, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide (GLP)-1. Ghrelin impairs carbohydrate and lipid metabolism in obese patients. Ghrelin is associated with elevated plasma levels of insulin, glucagon, and leptin. Specific activation of receptors and modulation by posttranslational modifications of ghrelin can control IR’s development in obesity, which is a promising area for research.

Growth Hormone Releasing Hormone Reduces Circulating Markers of Immune Activation in Parallel with Effects on Hepatic Immune Pathways in Individuals with HIV-infection and Nonalcoholic Fatty Liver Disease.

The growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis modulates critical metabolic pathways; however, little is known regarding effects of augmenting pulsatile GH secretion on immune function in humans. This study used proteomics and gene set enrichment analysis to assess effects of a GH releasing hormone (GHRH) analog, tesamorelin, on circulating immune markers and liver tissue in people with human immunodeficiency virus (HIV) (PWH) and nonalcoholic fatty liver disease (NAFLD). 92 biomarkers associated with immunity, chemotaxis, and metabolism were measured in plasma samples from 61 PWH with NAFLD who participated in a double-blind, randomized trial of tesamorelin versus placebo for 12 months. Gene set enrichment analysis was performed on serial liver biopsies targeted to immune pathways. Tesamorelin, compared to placebo, decreased interconnected proteins related to cytotoxic T-cell and monocyte activation. Circulating concentrations of 13 proteins were significantly decreased, and no proteins increased, by tesamorelin. These included 4 chemokines (CCL3, CCL4, CCL13 [MCP4], IL8 [CXCL8]), 2 cytokines (IL-10 and CSF-1), and 4 T-cell associated molecules (CD8A, CRTAM, GZMA, ADGRG1), as well as ARG1, Gal-9, and HGF. Network analysis indicated close interaction among the gene pathways responsible for these proteins, with imputational analyses suggesting down-regulation of a closely related cluster of immune pathways. Targeted transcriptomics using liver tissue confirmed a significant end-organ signal of down-regulated immune activation pathways. Long-term treatment with a GHRH analog reduced markers of T-cell and monocyte/macrophage activity, suggesting that augmentation of the GH axis may ameliorate immune activation in an HIV population with metabolic dysregulation, systemic and end organ inflammation. Clinical Trials Registration. NCT02196831.

Genetic deletion of the ghrelin receptor (GHSR) impairs growth and blunts endocrine response to fasting in Ghsr-IRES-Cre mice

ObjectiveThe orexigenic hormone ghrelin exerts its physiological effects by binding to and activating the growth hormone secretagogue receptor (GHSR). The recent development of a Ghsr-IRES-Cre knock-in mouse line has enabled to genetically access GHSR-expressing neurons. Inserting a Cre construct using a knock-in strategy, even when following an upstream internal ribosome entry site (IRES) can, however, interfere with expression of a targeted gene, with consequences for the phenotype emerging. This study aimed to phenotype, both physically and metabolically, heterozygous and homozygous Ghsr-IRES-Cre mice, with a view to discovering the extent to which the ghrelin signalling system remains functional in these mice. MethodsWe assessed feeding and arcuate nucleus (Arc) Fos activation in wild-type, heterozygous and homozygous Ghsr-IRES-Cre mice in response to peripherally-administered ghrelin. We also characterised their developmental and growth phenotypes, as well as their metabolic responses upon an overnight fast. ResultsInsertion of the IRES-Cre cassette into the 3′-untranslated region of the Ghsr gene led to a gene-dosage GHSR depletion in the Arc. Whereas heterozygotes remained ghrelin-responsive and more closely resembled wild-types, ghrelin had reduced orexigenic efficacy and failed to induce Arc Fos expression in homozygous littermates. Homozygotes had a lower body weight accompanied by a shorter body length, less fat tissue content, altered bone parameters, and lower insulin-like growth factor-1 levels compared to wild-type and heterozygous littermates. Moreover, both heterozygous and homozygous Ghsr-IRES-Cre mice lacked the usual fasting-induced rise in growth hormone (GH) and displayed an exaggerated drop in blood glucose and insulin compared to wild-types. Unexpectedly, fasting acyl-ghrelin levels were allele-dependently increased. ConclusionsOur data suggest that (i) heterozygous but not homozygous Ghsr-IRES-Cre mice retain the usual responsiveness to administered ghrelin, (ii) the impact of fasting on GH release and glucose homeostasis is altered even when only one copy of the Ghsr gene is non-functional (as in heterozygous Ghsr-IRES-Cre mice) and (iii) homozygous Ghsr-IRES-Cre mice exhibit growth retardation. Of the many transgenic models of suppressed ghrelin signalling, Ghsr-IRES-Cre mice emerge as best representing the full breadth of the expected phenotype with respect to body weight, growth, and metabolic parameters.

Gastroenteropancreatic neuroendocrine neoplasms: A clinical snapshot.

Our understanding about the epidemiological aspects, pathogenesis, molecular diagnosis, and targeted therapies of neuroendocrine neoplasms (NENs) have drastically advanced in the past decade. Gastroenteropancreatic (GEP) NENs originate from the enteroendocrine cells of the embryonic gut which share common endocrine and neural differentiation factors. Most NENs are well-differentiated, and slow growing. Specific neuroendocrine biomarkers that are used in the diagnosis of functional NENs include insulin, glucagon, vasoactive intestinal polypeptide, gastrin, somatostatin, adrenocorticotropin, growth hormone releasing hormone, parathyroid hormone-related peptide, serotonin, histamine, and 5-hydroxy indole acetic acid (5-HIAA). Biomarkers such as pancreatic polypeptide, human chorionic gonadotrophin subunits, neurotensin, ghrelin, and calcitonin are used in the diagnosis of non-functional NENs. 5-HIAA levels correlate with tumour burden, prognosis and development of carcinoid heart disease and mesenteric fibrosis, however several diseases, medications and edible products can falsely elevate the 5-HIAA levels. Organ-specific transcription factors are useful in the differential diagnosis of metastasis from an unknown primary of well-differentiated NENs. Emerging novel biomarkers include circulating tumour cells, circulating tumour DNA, circulating micro-RNAs, and neuroendocrine neoplasms test (NETest) (simultaneous measurement of 51 neuroendocrine-specific marker genes in the peripheral blood). NETest has high sensitivity (85%-98%) and specificity (93%-97%) for the detection of gastrointestinal NENs, and is useful for monitoring treatment response, recurrence, and prognosis. In terms of management, surgery, radiofrequency ablation, symptom control with medications, chemotherapy and molecular targeted therapies are all considered as options. Surgery is the mainstay of treatment, but depends on factors including age of the individual, location, stage, grade, functional status, and the heredity of the tumour (sporadic vs inherited). Medical management is helpful to alleviate the symptoms, manage inoperable lesions, suppress postoperative tumour growth, and manage recurrences. Several molecular-targeted therapies are considered second line to somatostatin analogues. This review is a clinical update on the pathophysiological aspects, diagnostic algorithm, and management of GEP NENs.

Growth Hormone Releasing Hormone in Endothelial Barrier Function

Growth hormone releasing hormone (GHRH) is the integral regulator of the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis. It exerts mitogenic effects in a plethora of progressive cancers. Recent evidence suggests the emerging role of that 44-amino acid (aa) neuropeptide in lung endothelial barrier function (EBF), which will be discussed herein.

Physiological and metabolic characteristics of novel double-mutant female mice with targeted disruption of both growth hormone-releasing hormone and growth hormone receptor.

Mice with disruptions of growth hormone‐releasing hormone (GHRH) or growth hormone receptor (GHR) exhibit similar phenotypes of prolonged lifespan and delayed age‐related diseases. However, these two models respond differently to calorie restriction indicating that they might carry different and/or independent mechanisms for improved longevity and healthspan. In order to elucidate these mechanisms, we generated GHRH and GHR double‐knockout mice (D‐KO). In the present study, we focused specifically on the characteristics of female D‐KO mice. The D‐KO mice have reduced body weight and enhanced insulin sensitivity compared to wild‐type (WT) controls. Growth retardation in D‐KO mice is accompanied by decreased GH expression in pituitary, decreased circulating IGF‐1, increased high‐molecular‐weight (HMW) adiponectin, and leptin hormones compared to WT controls. Generalized linear model‐based regression analysis, which controls for body weight differences between D‐KO and WT groups, shows that D‐KO mice have decreased lean mass, bone mineral density, and bone mineral content, but increased adiposity. Indirect calorimetry markers including oxygen consumption, carbon dioxide production, and energy expenditure were significantly lower in D‐KO mice relative to the controls. In comparison with WT mice, the D‐KO mice displayed reduced respiratory exchange ratio (RER) values only during the light cycle, suggesting a circadian‐related metabolic shift toward fat utilization. Interestingly, to date survival data suggest extended lifespan in D‐KO female mice.

Tesamorelin improves fat quality independent of changes in fat quantity.

Fat quality and quantity may affect health similarly or differently. Fat quality can be assessed by measuring fat density on CT scan (greater density = smaller, higher quality adipocytes). We assessed the effects of tesamorelin, a growth hormone-releasing hormone analogue that reduces visceral fat (VAT) quantity in some people living with HIV (PWH), on fat density. Participants from two completed, placebo-controlled, randomized trials of tesamorelin for central adiposity treatment in PWH were included if they had either a clinical response to tesamorelin (VAT decrease ≥8%, ≈70% of participants) or were placebo-treated. CT VAT and subcutaneous fat (SAT) density (Hounsfield Units, HU) were measured by a central blinded reader. Participants (193 responders, 148 placebo) were 87% male and 83% white. Baseline characteristics were similar across arms, including VAT (-91 HU both arms, P = 0.80) and SAT density (-94 HU tesamorelin, -95 HU placebo, P = 0.29). Over 26 weeks, mean (SD) VAT and SAT density increased in tesamorelin-treated participants only [VAT: +6.2 (8.7) HU tesamorelin, +0.3 (4.2) HU placebo, P < 0.0001; SAT: +4.0 (8.7) HU tesamorelin, +0.3 (4.8) HU placebo, P < 0.0001]. The tesamorelin effects persisted after controlling for baseline VAT or SAT HU and area, and VAT [+2.3 HU, 95% confidence interval (4.5-7.3), P = 0.001) or SAT (+3.5 HU, 95% confidence interval (2.3-4.7), P < 0.001] area change. In PWH with central adiposity who experienced VAT quantity reductions on tesamorelin, VAT and SAT density increased independent of changes in fat quantity, suggesting that tesamorelin also improves VAT and SAT quality in this group.

A Body Weight Sensor Regulates Prepubertal Growth via the Somatotropic Axis in Male Rats.

In healthy conditions, prepubertal growth follows an individual specific growth channel. Growth hormone (GH) is undoubtedly the major regulator of growth. However, the homeostatic regulation to maintain the individual specific growth channel during growth is unclear. We recently hypothesized a body weight sensing homeostatic regulation of body weight during adulthood, the gravitostat. We now investigated if sensing of body weight also contributes to the strict homeostatic regulation to maintain the individual specific growth channel during prepubertal growth. To evaluate the effect of increased artificial loading on prepubertal growth, we implanted heavy (20% of body weight) or light (2% of the body weight) capsules into the abdomen of 26-day-old male rats. The body growth, as determined by change in biological body weight and growth of the long bones and the axial skeleton, was reduced in rats bearing a heavy load compared with light load. Removal of the increased load resulted in a catch-up growth and a normalization of body weight. Loading decreased hypothalamic growth hormone releasing hormone mRNA, liver insulin-like growth factor (IGF)-1 mRNA, and serum IGF-1, suggesting that the reduced body growth was caused by a negative feedback regulation on the somatotropic axis and this notion was supported by the fact that increased loading did not reduce body growth in GH-treated rats. Based on these data, we propose the gravitostat hypothesis for the regulation of prepubertal growth. This states that there is a homeostatic regulation to maintain the individual specific growth channel via body weight sensing, regulating the somatotropic axis and explaining catch-up growth.

Growth Hormone Pulses and Liver Gene Expression Are Differentially Regulated by the Circadian Clock Gene Bmal1.

In this study, we found that loss of the circadian clock gene Bmal1 causes disruptions throughout the growth hormone (GH) axis, from hepatic gene expression to production of urinary pheromones and pheromone-dependent behavior. First, we show that Bmal1 knockout (KO) males elicit reduced aggressive responses from wild-type (WT) males and secrete lower levels of major urinary proteins (MUPs); however, we also found that a liver-specific KO of Bmal1 (liver-Bmal1-KO) produces a similar reduction in MUP secretion without a defect in aggressive behavior, indicating that the decrease in elicited aggression arises from another factor. We then shifted our investigation to determine the cause of MUP dysregulation in Bmal1 KO animals. Because the pulse pattern of GH drives sexually dimorphic expression of hepatic genes including MUPs, we examined GH pulsatility. We found that Bmal1 KO males have a female-like pattern of GH release, whereas liver-Bmal1-KO mice are not significantly different from either WT or Bmal1 KO. Since differential patterns of GH release regulate the transcription of many sexually dimorphic genes in the liver, we then examined hepatic gene transcription in Bmal1 KO and liver-Bmal1-KO mice. We found that while some female-predominant genes increase in the Bmal1 KO, there was no decrease in male-predominant genes, and little change in the liver-Bmal1-KO. We also found disrupted serum insulin growth factor 1 (IGF-1) and liver Igf1 messenger RNA in the Bmal1 KO mice, which may underlie the disrupted GH release. Overall, our findings differentiate between GH-pulse-driven and circadian-driven effects on hepatic genes, and the functional consequences of altered GH pulsatility.

Macrophages are activated in the rat anterior pituitary under chronic inflammatory conditions

In the anterior lobe of the pituitary gland (AP), non-endocrine cells regulate hormone secretion by endocrine cells. However, the functions of non-endocrine cells in the AP during chronic pain are largely unclear. Here, we show that macrophages, but not folliculostellate (FS) cells, were selectively increased in the AP in the complete Freund’s adjuvant (CFA)-induced chronic inflammatory pain model in rats. In addition, IL-1β expression was increased in the AP, and the IL-1β-immunopositive cells were identified as macrophages. On the other hand, increased macrophage density and IL-1β expression were not detected in a neuropathic pain model induced by partial sciatic nerve ligation (PSL). Furthermore, we found c-Fos expression specifically in the somatotrophs under the chronic inflammatory pain condition. Because IL-1β promotes growth hormone (GH) synthesis and release, our results suggest that AP macrophage contributes to GH release through IL-1βduring chronic inflammatory pain.

Comprehensive insights into the formation of metabolites of the ghrelin mimetics capromorelin, macimorelin and tabimorelin as potential markers for doping control purposes.

Analytical methods to determine the potential misuse of the ghrelin mimetics capromorelin (CP-424,391), macimorelin (macrilen, EP-01572) and tabimorelin (NN703) in sports were developed. Therefore, different extraction strategies, i.e. solid-phase extraction, protein precipitation, as well as a "dilute-and-inject" approach, from urine and EDTA-plasma were assessed and comprehensive in vitro/in vivo experiments were conducted, enabling the identification of reliable target analytes by means of high resolution mass spectrometry. The drugs' biotransformation led to the preliminary identification of 51 metabolites of capromorelin, 12 metabolites of macimorelin and 13 metabolites of tabimorelin. Seven major metabolites detected in rat urine samples collected post-administration of 0.5-1.0 mg of a single oral dose underwent in-depth characterization, facilitating their implementation into future confirmatory test methods. In particular, two macimorelin metabolites exhibiting considerable abundances in post-administration rat urine samples were detected, which might contribute to an improved sensitivity, specificity, and detection window in case of human sports drug testing programs. Further, the intact drugs were implemented into World Anti-Doping Agency-compliant initial testing (limits of detection 0.02-0.60 ng/ml) and confirmation procedures (limits of identification 0.18-0.89 ng/ml) for human urine and blood matrices. The obtained results allow extension of the test spectrum of doping agents in multitarget screening assays for growth hormone-releasing factors from human urine.

Detection of the synthetic peptide ipamorelin in dried blood spots by means of UHPLC-HRMS

Growth hormone-releasing peptides (GHRPs) are synthetic peptides that stimulate the release of growth hormones from the hypothalamus and pituitary gland. Among these, ipamorelin is a highly selective, potent and effective pentapeptide belonging to the class of growth hormone secretagogues (GHS). Because of clinical monitoring and the potential abuse by athletes in amateur and elite sports, detection methods able to identify GHRPs in biological samples are increasingly needed. As an alternative to conventional procedures, testing of Dried Blood Spots (DBS) is gaining increasing attention, since its low volume sampling is easy and scarcely invasive. In this study, an ultra high pressure liquid chromatography–high resolution mass spectrometry method was developed and validated for the screening of ipamorelin in DBS. Ipamorelin was extracted from DBS by liquid extraction and ultrasonic treatment, then detected by the acquisition of high-resolution fragmentation spectra. The method proved satisfactory in terms of sensitivity, specificity, linearity, recovery, precision and ion suppression/enhancement effects. The mass error of the precursor and fragment ions was lower than 5 ppm. Since ipamorelin was successfully detected in DBS with a detection limit of 2.5 ng/mL, the combination of DBS and high resolution mass spectrometry proved to be a suitable and effective method to detect small peptides in blood at low levels. This approach looks promising for targeted and untargeted analysis in clinical monitoring and sport drug testing, especially when unknown synthetic peptides represent the target analytes.

Protective effects of growth hormone-releasing hormone analogs in DSS-induced colitis in mice

Besides its metabolic and endocrine effects, growth hormone (GH)-releasing hormone (GHRH) is involved in the modulation of inflammation. Recently synthetized GHRH antagonist MIA-690 and MR-409, GHRH agonist, developed by us have shown potent pharmacological effects in various experimental paradigms. However, whether their administration modify resistance to chronic inflammatory stimuli in colon is still unknown. Ex vivo results demonstrated that MIA-690 and MR-409 inhibited production of pro-inflammatory and oxidative markers induced by lipopolysaccharide on isolated mouse colon specimens. In vivo, both MIA-690 and MR-409 have also been able to decrease the responsiveness to nociceptive stimulus, in hot plate test. Additionally, both peptides also induced a decreased sensitivity to acute and persistent inflammatory stimuli in male mice, in formalin test and dextran sodium sulfate (DSS)-induced colitis model, respectively. MIA-690 and MR-409 attenuate DSS-induced colitis with particular regard to clinical manifestations, histopathological damage and release of pro-inflammatory and oxidative markers in colon specimens. Respect to MR-409, MIA-690 showed higher efficacy in inhibiting prostaglandin (PG)E2, 8-iso-PGF2α and serotonin (5-HT) levels, as well as tumor necrosis factor (TNF)-α, interleukin (IL)-6 and nitric oxide synthase gene expression in colon specimens of DSS-induced colitis. Furthermore, MIA-690 decreased serum insulin-like growth factor (IGF)-1 levels in mice DSS-treated, respect to MR-409. Thus, our findings highlight the protective effects of MIA-690 and MR-409 on inflammation stimuli. The higher antinflammatory and antioxidant activities observed with MIA-690 could be related to decreased serum IGF-1 levels.

Ghrelin as an Anti-Sepsis Peptide: Review.

Sepsis continues to produce widespread inflammation, illness, and death, prompting intensive research aimed at uncovering causes and therapies. In this article, we focus on ghrelin, an endogenous peptide with promise as a potent anti-inflammatory agent. Ghrelin was discovered, tracked, and isolated from stomach cells based on its ability to stimulate release of growth hormone. It also stimulates appetite and is shown to be anti-inflammatory in a wide range of tissues. The anti-inflammatory effects mediated by ghrelin are a result of both the stimulation of anti-inflammatory processes and an inhibition of pro-inflammatory forces. Anti-inflammatory processes are promoted in a broad range of tissues including the hypothalamus and vagus nerve as well as in a broad range of immune cells. Aged rodents have reduced levels of growth hormone (GH) and diminished immune responses; ghrelin administration boosts GH levels and immune response. The anti-inflammatory functions of ghrelin, well displayed in preclinical animal models of sepsis, are just being charted in patients, with expectations that ghrelin and growth hormone might improve outcomes in patients with sepsis.