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Teramoto S, Tahara S, Hattori Y, Kondo A, Morita A. Assessment of anterior pituitary reserve capacity based on growth hormone response to growth hormone-releasing peptide-2 test in the elderly. Growth Horm IGF Res 2023; 71:101545. [PMID: 37295337 DOI: 10.1016/j.ghir.2023.101545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/23/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023]
Abstract
OBJECTIVE The growth hormone (GH)-releasing peptide-2 (GHRP-2) test is relatively safe among endocrine stimulation tests for the elderly. We investigated whether anterior pituitary function in elderly patients could be assessed on the basis of GH response to the GHRP-2 test. DESIGN Sixty-five elderly patients aged 65 years and older with non-functioning pituitary neuroendocrine tumor (PitNET) who underwent pituitary surgery and preoperative endocrine stimulation tests were classified into the "GH normal group" and "GH deficiency group" based on GH response to the GHRP-2 test. The baseline characteristics and anterior pituitary function were compared between the groups. RESULTS Thirty-two patients were assigned to the GH normal group and 33 to the GH deficiency group. The cortisol and adrenocorticotropic hormone (ACTH) results in the corticotropin-releasing hormone test were significantly higher in the GH normal group than in the GH deficiency group (p < 0.001). The relationship between the cortisol and ACTH results and the GH response revealed significant correlations (p < 0.001). In addition, receiver operating characteristic curve analysis identified that the optimal cut-off point for a peak GH level in the correlation between adrenocortical function and GH response to the GHRP-2 test was 8.08 ng/mL (specificity 0.868, sensitivity 0.852). CONCLUSION The present study indicated that adrenocortical function was significantly correlated with GH response to the GHRP-2 test in elderly patients before pituitary surgery. For elderly patients with non-functioning PitNET, GH response to the GHRP-2 test may support in diagnosing adrenocortical insufficiency.
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Affiliation(s)
- Shinichiro Teramoto
- Department of Neurological Surgery, Nippon Medical School, Tokyo 113-8603, Japan; Department of Neurosurgery, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
| | - Shigeyuki Tahara
- Department of Neurological Surgery, Nippon Medical School, Tokyo 113-8603, Japan
| | - Yujiro Hattori
- Department of Neurological Surgery, Nippon Medical School, Tokyo 113-8603, Japan
| | - Akihide Kondo
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan
| | - Akio Morita
- Department of Neurological Surgery, Nippon Medical School, Tokyo 113-8603, Japan
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Takeshita K, Abe I, Nagata M, Ochi K, Senda Y, Koga M, Ohe K, Abe M, Kudo T, Kobayashi K. Clinical investigation of a unique type of hypothalamic adrenal insufficiency. Medicine (Baltimore) 2022; 101:e30597. [PMID: 36253985 PMCID: PMC9575774 DOI: 10.1097/md.0000000000030597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Hypothalamic adrenal insufficiency (AI) is a rare but distinct type of AI. The leading cause of hypothalamic AI is a secondary side-effect of exogenous steroid intake, particularly in large amounts and/or long-term periods. The next cause would be the effect of the tumor in the hypothalamic lesions. We show here 9 cases of hypothalamic AI without any disorder on imagings and a history of steroid administration. All patients had general fatigue; 7 patients (77.8%) had a history of hypoglycemia; 5 patients (55.6%) had a history of hypotension. None of the patients had hyponatremia, hyperkalemia, or eosinophilia. Their morning plasma adrenocorticotropic hormone (ACTH) value was low at 8.5 ± 4.2 pg/mL, and serum cortisol value was low at 4.5 ± 1.3 µg/dL. All patients demonstrated normal responses during the corticotropin-releasing hormone loading (CRH) test but inadequate responses during the insulin tolerance test (ITT). After hydrocortisone replacement therapy, their morning plasma ACTH and serum cortisol values were significantly recovered (P < .05). Moreover, more than half of the patients were fine after discontinuing hydrocortisone replacement therapy. These results indicate that this unique type of hypothalamic AI has a curable clinical course making hydrocortisone replacement therapy a novel therapeutic option.
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Affiliation(s)
- Kaori Takeshita
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
| | - Ichiro Abe
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
- *Correspondence: Ichiro Abe, Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, 1-1-1, Zokumyoin, Chikushino, Fukuoka, 818-8502, Japan (e-mail: )
| | - Mai Nagata
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
| | - Kentaro Ochi
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
| | - Yuki Senda
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
| | - Midori Koga
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
| | - Kenji Ohe
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan
| | - Makiko Abe
- Department of Preventive Medicine and Public Health, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Tadachika Kudo
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
| | - Kunihisa Kobayashi
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, Chikushino, Fukuoka, Japan
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Suzuki S, Ruike Y, Ishiwata K, Naito K, Igarashi K, Ishida A, Fujimoto M, Koide H, Horiguchi K, Tatsuno I, Yokote K. Clinical usefulness of the growth hormone-releasing peptide-2 test for hypothalamic-pituitary disorder. J Endocr Soc 2022; 6:bvac088. [PMID: 35795807 PMCID: PMC9249372 DOI: 10.1210/jendso/bvac088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Indexed: 11/19/2022] Open
Abstract
Abstract
Purpose
Growth hormone deficiency (GHD) develops early in patients with hypothalamic-pituitary disorder and is frequently accompanied by other anterior pituitary hormone deficiencies including secondary adrenal insufficiency (AI). A growth hormone-releasing peptide-2 (GHRP2), which is wildly used for the diagnosis of patients with GHD, has been considered to induce not only growth hormone (GH) release but also ACTH release. However, its clinical usefulness in hypothalamic-pituitary disorder is unclear.
Methods
The GHRP2 test, a cosyntropin stimulation test, corticotropin-releasing hormone (CRH) tests and/or insulin tolerance tests (ITTs) were performed on 36 patients having hypothalamic-pituitary disorder.
Results
Twenty-two (61%) had severe GHD, and 3 (8%) had moderate GHD by GHRP2. There was no difference in baseline ACTH and cortisol between non-GHD, moderate GHD and severe GHD participants. However, a cosyntropin stimulation test and subsequent CRH tests and/or ITTs revealed that 17 (47%) had secondary AI and 16/17 (94%) cases of secondary AI were concomitant with severe GHD. ROC curve analysis demonstrated that the ACTH response in the GHRP2 test was useful for screening pituitary-AI, with a cut-off value of 1.55-fold (83% sensitivity and 88% specificity). Notably, the combination of ACTH response and the peak cortisol level in the GHRP2 test using each cut-off value (1.55-fold and 10 µg/dl, respectively) showed high specificity (100%) with high accuracy (0.94) for diagnosis of pituitary-AI.
Conclusion
We recommend measuring ACTH as well as GH during the GHRP2 test to avoid overlooking and delays in diagnosis of secondary AI that frequently accompanies GHD.
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Affiliation(s)
- Sawako Suzuki
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Yutarou Ruike
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Kazuki Ishiwata
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Kumiko Naito
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Katsushi Igarashi
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Akiko Ishida
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Masanori Fujimoto
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | - Hisashi Koide
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
| | | | | | - Koutaro Yokote
- Department of Endocrinology, Hematology and Gerontology , Chiba University Graduate School of Medicine
- Department of Diabetes , Metabolism and Endocrinology, Chiba University Hospital
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Rare variant of the epigenetic regulator SMCHD1 in a patient with pituitary hormone deficiency. Sci Rep 2020; 10:10985. [PMID: 32620854 PMCID: PMC7335161 DOI: 10.1038/s41598-020-67715-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 06/12/2020] [Indexed: 11/17/2022] Open
Abstract
Isolated hypogonadotropic hypogonadism (IHH), combined pituitary hormone deficiency (CPHD), and septo-optic dysplasia (SOD) constitute a disease spectrum whose etiology remains largely unknown. This study aimed to clarify whether mutations in SMCHD1, an epigenetic regulator gene, might underlie this disease spectrum. SMCHD1 is a causative gene for Bosma arhinia microphthalmia syndrome characterized by arhinia, microphthalmia and IHH. We performed mutation screening of SMCHD1 in patients with etiology-unknown IHH (n = 31) or CPHD (n = 43, 19 of whom also satisfied the SOD diagnostic criteria). Rare variants were subjected to in silico analyses and classified according to the American College of Medical Genetics and Genomics guidelines. Consequently, a rare likely pathogenic variant, p.Asp398Asn, was identified in one patient. The patient with p.Asp398Asn exhibited CPHD, optic nerve hypoplasia, and a thin retinal nerve fiber layer, and therefore satisfied the criteria of SOD. This patient showed a relatively low DNA methylation level of the 52 SMCHD1-target CpG sites at the D4Z4 locus. Exome sequencing for the patient excluded additional variants in other IHH/CPHD-causative genes. In vitro assays suggested functional impairment of the p.Asp398Asn variant. These results provide the first indication that SMCHD1 mutations represent a rare genetic cause of the HH-related disease spectrum.
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Li N, Yang Z, Li Q, Yu Z, Chen X, Li JC, Li B, Ning SL, Cui M, Sun JP, Yu X. Ablation of somatostatin cells leads to impaired pancreatic islet function and neonatal death in rodents. Cell Death Dis 2018; 9:682. [PMID: 29880854 PMCID: PMC5992210 DOI: 10.1038/s41419-018-0741-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/20/2018] [Accepted: 05/22/2018] [Indexed: 02/08/2023]
Abstract
The somatostatin (SST)-secreting cells were mainly distributed in the pancreatic islets, brain, stomach and intestine in mammals and have many physiological functions. In particular, the SST-secreting δ cell is the third most common cell type in the islets of Langerhans. Recent studies have suggested that dysregulation of paracrine interaction between the pancreatic δ cells and β cells results in impaired glucose homeostasis and contributes to diabetes development. However, direct evidence of the functional importance of SST cells in glucose homeostasis control is still lacking. In the present study, we specifically ablated SST-secreting cells by crossing Sst-cre transgenic mice with R26 DTA mice (Sst Cre R26 DTA ). The Sst Cre R26 DTA mice exhibited neonatal death. The life spans of these mice with severe hypoglycemia were extended by glucose supplementation. Moreover, we observed that SST cells deficiency led to increased insulin content and excessive insulin release, which might contribute to the observed hypoglycemia. Unexpectedly, although SST is critical for the regulation of insulin content, factors other than SST that are produced by pancreatic δ cells via their endogenous corticotropin-releasing hormone receptor 2 (CRHR2) activity play the main roles in maintaining normal insulin release, as well as neonatal glucose homeostasis in the resting state. Taken together, our results identified that the SST cells in neonatal mouse played critical role in control of insulin release and normal islet function. Moreover, we provided direct in vivo evidence of the functional importance of the SST cells, which are essential for neonatal survival and the maintenance of glucose homeostasis.
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Affiliation(s)
- Na Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Zhao Yang
- Department of Biochemistry and Molecular Biology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Qing Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Zhen Yu
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Xu Chen
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Jia-Cheng Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Bo Li
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Shang-Lei Ning
- Department of General Surgery, Qilu Hospital Affiliated to Shandong University, Jinan, Shandong, 250012, China
| | - Min Cui
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China
| | - Jin-Peng Sun
- Department of Biochemistry and Molecular Biology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China.,School of Medicine, Duke University, Durham, North Carolina, 27705, USA
| | - Xiao Yu
- Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Basic Medical Sciences, Jinan, Shandong, 250012, China.
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Arimura H, Hashiguchi H, Yamamoto K, Shinnakasu A, Arimura A, Kikuchi A, Deguchi T, Habu M, Fujio S, Arita K, Nishio Y. Investigation of the clinical significance of the growth hormone-releasing peptide-2 test for the diagnosis of secondary adrenal failure. Endocr J 2016; 63:533-44. [PMID: 27020037 DOI: 10.1507/endocrj.ej15-0587] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The aim of this study was to evaluate the ability of the growth hormone-releasing peptide-2 (GHRP-2) test to clinically diagnose hypothalamo-pituitary-adrenal (HPA) axis failure. We performed an insulin tolerance test (ITT), CRH stimulation test, and GHRP-2 test on 47 patients suspected of having a hypothalamo-pituitary disorder. Patients with pituitary disorders had significantly lower ACTH responses to the GHRP-2 test compared to patients with hypothalamic disorders and the control group. In contrast, peak cortisol levels in response to the GHRP-2 test were significantly lower in both hypothalamic and pituitary disorder cases compared with the control group. Assignment of a cut-off value of 11.6 μg/dL for the peak serum cortisol level demonstrated that the GHRP-2 test was able to predict secondary hypoadrenalism with 88.9% specificity and 89.7% sensitivity. The responses of ACTH and cortisol to the GHRP-2 test had no correlation to the CRH test, suggesting the involvement of a different mechanism of ACTH secretion. These results indicate that the GHRP-2 test may induce ACTH secretion from the pituitary gland through direct stimulation. Although the GHRP-2 test does not have the same predictive value as the insulin tolerance test (ITT), it has similar diagnostic potential as the CRH stimulation test for evaluating HPA axis failure.
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Affiliation(s)
- Hiroshi Arimura
- Department of Diabetes and Endocrine Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8520, Japan
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Ohara N, Kojima N, Sato T, Ikarashi T, Sone H, Oki Y, Kamoi K, Hara M, Sasaki H. Type 1 diabetes mellitus and isolated adrenocorticotropin deficiency manifested by parkinsonism: a case report and literature review. Intern Med 2015; 54:2629-35. [PMID: 26466701 DOI: 10.2169/internalmedicine.54.5022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A 67-year-old woman developed isolated adrenocorticotropin deficiency (IAD), which manifested as lethargy, a 20-kg body weight loss, hypoglycemia, and parkinsonism, and began corticosteroid replacement. Her symptoms resolved rapidly, and her weight returned to normal within six months. However, she then developed slowly progressive type 1 diabetes mellitus (T1D) with co-existing Hashimoto thyroiditis, and commenced insulin therapy. To our knowledge, this is the first reported case of parkinsonism associated with IAD. In addition, because diabetes mellitus, including T1D, could be latent in patients with untreated IAD, careful assessment of glucose metabolism is needed after commencing corticosteroid replacement until weight regain is achieved.
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Affiliation(s)
- Nobumasa Ohara
- Department of Endocrinology and Metabolism, Niigata Medical Center, Japan
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Tsukamoto N, Otsuka F, Miyoshi T, Inagaki K, Nakamura E, Terasaka T, Takeda M, Ogura T, Iwasaki Y, Makino H. Functional interaction of bone morphogenetic protein and growth hormone releasing peptide in adrenocorticotropin regulation by corticotrope cells. Mol Cell Endocrinol 2011; 344:41-50. [PMID: 21742013 DOI: 10.1016/j.mce.2011.06.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/29/2011] [Accepted: 06/18/2011] [Indexed: 11/21/2022]
Abstract
Mechanisms by which GHRP stimulates ACTH release in corticotrope cells were investigated using mouse corticotrope AtT20 cells by focusing on the biological activity of BMP-4. GHRP-2 increased ACTH and cAMP secretion by AtT20 cells; however, its effects were less potent than the effects of CRH. BMP-4 suppressed basal ACTH production and POMC transcription, and the inhibition of endogenous BMP receptor signaling led to an increase in ACTH production. Of note, BMP-4 suppressed ACTH production and POMC-promoter activity induced by CRH more efficaciously than that induced by GHRP-2. BMP-4 had no significant effect on cAMP synthesis induced by CRH or GHRP-2. Stimulation with CRH, but not GHRP-2, activated ERK1/2, p38, SAPK/JNK and Akt phosphorylation, in which CRH-induced phosphorylation of ERK and p38 was suppressed by BMP-4. GHRP-2-induced ACTH secretion was not affected by inhibitors of ERK, p38 and Akt pathways, which effectively suppressed CRH-induced ACTH release. Blockage of the cAMP-PKA pathway reversed CRH- as well as GHRP-2-induced ACTH secretion. Furthermore, the inhibition of ERK and p38 significantly reduced cAMP synthesis induced by CRH but not by GHRP-2. Thus, CRH activates ACTH production through ERK and p38 pathways in addition to the cAMP-PKA pathway, which is also activated downstream of MAPK. On the other hand, GHRP-2-induced ACTH production was predominantly linked to the cAMP-PKA pathway. Moreover, CRH and GHRP-2 upregulated BMP receptor signaling, while BMP-4, CRH and GHRP-2 had no significant effect on the expression level of GHSR. In addition, GHRP-2 suppressed the expression of Smad7, which is an inhibitor of the BMP-Smad1/5/8 pathway. Collectively, the results revealed a functional interaction between GHRP-2 and BMP signaling, in which endogenous BMP may act as an autoregulatory system in controlling ACTH production.
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Affiliation(s)
- Naoko Tsukamoto
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
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Kamoi K, Shimatsu A, Kobayashi M. Is there an undiscovered neurocircuit for regulating GH secretion? -Pitfalls of GHRP-2 and ITT as GH provocative tests-. Endocr J 2010; 57:1071-9. [PMID: 20953065 DOI: 10.1507/endocrj.k10e-198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
GH secretion is mainly regulated at the hypothalamus by a dual interplay between growth hormone releasing hormone (GHRH) and somatostatin, which are modulated by various factors. We examined the regulatory mechanism of GH secretion in an apparently healthy young man without decreased IGF-1 concentration and nocturnal GH secretion, but who showed low responses to insulin tolerance (ITT) and to GHRP-2 tests. The patient also had no GH response to acute aerobic exercise. However, he had normal secretion of pituitary hormone based on hypothalamic releasing hormone tests combined with CRH, GRH as GHRH, LH-RH and TRH. In addition, he had a GH response without paradoxical secretion to TRH stimulation as well as an ACTH response to subcutaneous glucagon stimulation, and AVP secretion responded to 5% hypertonic saline infusion, though it was not adequately stimulated by ITT. MRI showed no structural abnormalities in the hypothalamus-pituitary gland. These findings indicate that this subject may have an undiscovered neurocircuit for regulating GH secretion, as well as other neurohormones, to maintain homeostasis, even though there were low responses of the hormones to ITT and GHRP-2 stimuli, probably via altered secretion of hypothalamic hormones.
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Affiliation(s)
- Kyuzi Kamoi
- The Center of Diabetes and Endocrine & Metabolism Disease, Nagaoka Red Cross Hospital, Nagaoka, Japan.
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