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ABSTRACT: Previously, we reported that exogenous administration of ghrelin ameliorates glucose metabolism in a neonate streptozotocin (STZ)-induced diabetic rat model through enhancement of β-cell proliferation. However, it was not clear whether the observed β-cell proliferation was a direct or indirect effect (e.g., via orexigenic or growth hormone-stimulated pathways) of ghrelin activity. Here, we aim to investigate whether ghrelin directly impacts β-cell proliferation after STZ-induced injury in mice. Seven-week-old male rat insulin II promoter-ghrelin internal ribosomal sequence ghrelin O-acyltransferase transgenic (RIP-GG Tg) mice, which have elevated pancreatic ghrelin levels, but only minor changes in plasma ghrelin levels, when fed a medium-chain triglyceride-rich diet, were treated with STZ. Then, serum insulin, pancreatic insulin mRNA expression, and islet histology were evaluated. We found that the serum insulin levels, but not blood glucose levels, of RIP-GG Tg mice were significantly ameliorated 14 days post-STZ treatment. Pancreatic insulin mRNA expression was significantly elevated in RIP-GG Tg mice, and β-cell numbers in islets were increased. Furthermore, the number of phospho-histone H3(+) or Ki67(+) proliferating β cells was significantly elevated in RIP-GG Tg mice, while the apoptotic indices within the islets, as determined by the TUNEL assay, were not changed. These results indicated that ghrelin can directly stimulate β-cell proliferation in vivo after β-cell injury even without its orexigenic or GH-stimulating activities, although it did not have enough impacts to normalize the glucose tolerance in adult mice.
AJP Endocrinology and Metabolism 05/2013; · 4.75 Impact Factor
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ABSTRACT: Neuroblastoma is the second most common type of solid tumor in children and is commonly found in the adrenal medulla. Recently, we developed transgenic mice exhibiting tumors bilaterally in the adrenal medulla through the expression of SV40 T-antigen. Since these transgenic mice facilitate the development of new therapeutic approaches for neuroblastoma, non-invasive monitoring methods are required for serial measurement of tumor progression. In this study, we monitored the serial progression of adrenal tumors in transgenic mice by magnetic resonance imaging (MRI) of 9.4 T vertical type, and calculated the tumor volume. The accuracy of the tumor volume determination by MRI was verified by standard volume measurements at autopsy. Adrenal tumors as small as 1.5 mm in diameter were detected and quantitatively measured in the transgenic mice by in vivo MRI without using exogenous contrast agents on T(2)-weighted spin echo images. The tumor sizes by MRI correlated better with tumor weight than the volume by calculation with a caliper. Furthermore, we monitored the change of tumor volume following administration of doxorubicin at weekly intervals. The tumor progression and regression following doxorubicin treatment in the individual mice could be observed by serial MRI. From these findings, non-invasive MRI is likely to be useful for monitoring the response of spontaneous tumors to therapeutic drugs.
Experimental and therapeutic medicine 07/2012; 4(1):61-64.
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ABSTRACT: Ghrelin, a natural ligand for the growth hormone (GH)-secretagogue receptor (GHS-R), is now known to play a role in a number of different physiological processes. For example, ghrelin increases GH secretion, feeding, and body weight when administered centrally or peripherally. These unique effects of ghrelin should be invaluable for the development of novel treatments and disease diagnostic techniques. Clinical trials have already been performed to assess the utility of ghrelin for the treatment of several disorders including anorexia, cachexia, and GH-related disorders. This review summarizes the recent advances in this area of research.
European Journal of Internal Medicine 04/2012; 23(3):197-202. · 2.00 Impact Factor
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ABSTRACT: It has been indicated that T-box 21 (TBX21) and H 2.0-like homeobox (HLX) are transcription factors related to the differentiation of T helper 1 cells, whereas GATA-binding protein 3 is the master transcription factor of T helper 2 cells.
We genotyped -1514T/C (rs17250932) and -1993T/C (rs4794067) polymorphisms of TBX21, - 742C/G polymorphism (rs2184658) of HLX and -1420G/A polymorphism (rs1269486) of GATA3 in genomic DNA samples from Japanese patients; 51 patients with severe Hashimoto's disease (HD), 39 with mild HD, 66 with intractable Graves' disease (GD), in whom remission was difficult to induce, 47 with GD in remission and 79 healthy volunteers.
The T alleles of the TBX21-1514T/C and -1993T/C polymorphisms were more frequent in patients with intractable GD than in those with GD in remission. Among individuals with the TBX21-1993TT genotype, the G allele of HLX-742C/G polymorphism, which correlates with low HLX expression, was more frequent in patients with intractable GD than in those with GD in remission.
Functional polymorphisms in TBX21 are associated with the development of autoimmune thyroid diseases and prognosis of GD, and a functional polymorphism in HLX in combination with the TBX21 polymorphism is also associated with the prognosis of GD.
Autoimmunity 03/2012; 45(2):129-36. · 2.47 Impact Factor
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ABSTRACT: Whereas ghrelin is produced primarily in the stomach, a small amount of it is produced in pancreatic islets. Although exogenous administration of ghrelin suppresses insulin secretion in vitro or in vivo, the role of intraislet ghrelin in the regulation of insulin secretion in vivo remains unclear. To understand the physiological role of intraislet ghrelin in insulin secretion and glucose metabolism, we developed a transgenic (Tg) mouse model, rat insulin II promoter ghrelin-internal ribosomal entry site-ghrelin O-acyl transferase (RIP-GG) Tg mice, in which mouse ghrelin cDNA and ghrelin O-acyltransferase are overexpressed under the control of the rat insulin II promoter. Although pancreatic desacyl ghrelin levels were elevated in RIP-GG Tg mice, pancreatic ghrelin levels were not altered in animals on a standard diet. However, when Tg mice were fed a medium-chain triglyceride-rich diet (MCTD), pancreatic ghrelin levels were elevated to ∼16 times that seen in control animals. It seems likely that the gastric ghrelin cells possess specific machinery to provide the octanoyl acid necessary for ghrelin acylation but that this machinery is absent from pancreatic β-cells. Despite the overexpression of ghrelin, plasma ghrelin levels in the portal veins of RIP-GG Tg mice were unchanged from control levels. Glucose tolerance, insulin secretion, and islet architecture in RIP-GG Tg mice were not significantly different even when the mice were fed a MCTD. These results indicate that intraislet ghrelin does not play a major role in the regulation of insulin secretion in vivo.
AJP Endocrinology and Metabolism 11/2011; 302(4):E403-8. · 4.75 Impact Factor
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ABSTRACT: Ghrelin requires a fatty acid modification for binding to the GH secretagogue receptor. Acylation of the Ser3 residue of ghrelin is essential for its biological activities. We hypothesized that acyl-CoA is the fatty acid substrate for ghrelin acylation. Because serum octanoyl-CoA levels are altered by fatty acid oxidation disorders, we examined circulating ghrelin levels in affected patients.
Blood levels of acyl (A) and des-acyl (D) forms of ghrelin and acylcarnitine of patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and glutaric aciduria type II (GA2) were measured.
Plasma acyl ghrelin levels and A/D ratios increased in patients with MCAD deficiency or GA2 when compared with normal subjects. Reverse-phase HPLC confirmed that n-octanoylated ghrelin levels were elevated in these patients.
Changing serum medium-chain acylcarnitine levels may affect circulating acyl ghrelin levels, suggesting that acyl-CoA is the substrate for ghrelin acylation.
European Journal of Endocrinology 11/2011; 166(2):235-40. · 3.42 Impact Factor
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Kazuhiko Nakabayashi,
Atsushi Tajima,
Ken Yamamoto,
Atsushi Takahashi,
Kenichiro Hata,
Yasuo Takashima,
Midori Koyanagi,
Hirofumi Nakaoka, Takashi Akamizu,
Naofumi Ishikawa,
Sumihisa Kubota,
Shiro Maeda,
Tatsuhiko Tsunoda,
Michiaki Kubo,
Naoyuki Kamatani,
Yusuke Nakamura,
Takehiko Sasazuki,
Senji Shirasawa
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ABSTRACT: To identify genetic variants that confer the risk of Graves' disease (GD) in the Japanese population, we conducted a two-stage genome-wide association study (GWAS) using 1119 Japanese individuals with GD and 2718 unrelated controls, and a subsequent replication study using independent 432 GD cases and 1157 controls. We identified 34 single nucleotide polymorphisms (SNPs) to be significantly associated with GD in the GWAS phase. Twenty-two out of 34 SNPs remained positive in the replication study. All 22 SNPs were located within the major histocompatibility complex (MHC) locus on chromosome 6p21. No strong long-range linkage disequilibrium (LD) was observed among the 22 SNPs, indicating independent involvement of multiple loci within the MHC with the risk of GD. Multivariate stepwise logistic regression analysis selected rs3893464, rs4313034, rs3132613, rs4248154, rs2273017, rs9394159 and rs4713693, as markers for independent risk loci for GD. The analysis of LD between these seven SNPs and tagging SNPs for GD-associated human leukocyte antigen (HLA) alleles in the Japanese population (HLA-DPB1(*)0501 and HLA-A(*)0206) demonstrated that all of and five of seven SNPs were not in strong LD with HLA-DPB1(*)0501 and HLA-A(*)0206, respectively. Although causal variants remain to be identified, our results demonstrate the existence of multiple GD susceptibility loci within the MHC region.
Journal of Human Genetics 09/2011; 56(11):772-8. · 2.57 Impact Factor
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ABSTRACT: To understand the physiological role of ghrelin, it is crucial to study both the actions of ghrelin and the regulation of ghrelin secretion. Although ghrelin actions have been extensively revealed, the direct factors regulating ghrelin secretion by ghrelin-producing cells (X/A-like cells), however, is not fully understood. In this study, we examined the effects of peptide hormones and neurotransmitters on in vitro ghrelin secretion by the recently developed ghrelin-producing cell line MGN3-1. Oxytocin and vasopressin significantly stimulated ghrelin secretion by MGN3-1 cells. Because MGN3-1 cells express only oxytocin receptor mRNA, not vasopressin receptor mRNA, oxytocin is the likely regulator, with the effect of vasopressin mediated by a cross-reaction. We also discovered that dopamine stimulates ghrelin secretion from MGN3-1 cells in a similar manner to the previously known ghrelin stimulators, epinephrine and norepinephrine. MGN3-1 cells expressed mRNA encoding dopamine receptors D1a and D2. The dopamine receptor D1 agonist fenoldopam stimulated ghrelin secretion, whereas the D2, D3 agonist bromocriptine did not. Furthermore, the D1 receptor antagonist SKF83566 attenuated the stimulatory effect of dopamine. These results indicate that the stimulatory effect of dopamine on ghrelin secretion is mediated by the D1a receptor. In conclusion, we identified two direct regulators of ghrelin, oxytocin and dopamine. These findings will provide new direction for further studies seeking to further understand the regulation of ghrelin secretion, which will in turn lead to greater understanding of the physiological role of ghrelin.
Endocrinology 07/2011; 152(7):2619-25. · 4.46 Impact Factor
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ABSTRACT: Ghrelin, which is a natural ligand for the growth hormone (GH)-secretagogue receptor (GHS-R), stimulates food intake in both animals and humans. Ghrelin is the only circulating hormone known to stimulate appetite in humans. Ghrelin also stimulates GH secretion and inhibits the production of anorectic proinflammatory cytokines. As GH is an anabolic hormone, protein stores are spared at the expense of fat during conditions of caloric restriction. Thus, ghrelin exhibits anti-cachectic actions via both GH-dependent and -independent mechanisms. Several studies are evaluating the efficacy of ghrelin in the treatment of cachexia caused by a variety of diseases, including congestive heart failure, chronic obstructive pulmonary disease, cancer, and end-stage renal disease. These studies will hopefully lead to the development of novel therapeutic applications for ghrelin in the future. This review summarizes the recent advances in this area of research.
Peptides 05/2011; 32(11):2295-300. · 2.43 Impact Factor
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ABSTRACT: After the discovery of ghrelin, we attempted to generate ghrelin gene transgenic (Tg) mice. These animals, however, produced only des-acyl ghrelin, which lacked the n-octanoyl modification at Ser(3) necessary to manifest ghrelin activity. Because the mechanism for acyl-modification of ghrelin had been unclear until the recent identification of GOAT (ghrelin O-acyltransferase), it had been difficult to generate Tg mice overexpressing ghrelin using standard procedures. Therefore, we planned to generate Tg mice overexpressing a ghrelin analog, which possessed ghrelin-like activity in the absence of acylation at Ser(3) and could be synthesized in vivo. As the replacement of Ser(3) of ghrelin with Trp(3) (Trp(3)-ghrelin) preserves a low level of ghrelin activity and Trp(3)-ghrelin can be synthesized in vivo, we generated mice overexpressing Trp(3)-ghrelin by using the hSAP (human serum-amyloid-P) promoter. Plasma Trp(3)-ghrelin concentrations in the Tg mice were approximately 85-fold higher than plasma ghrelin concentrations in non-Tg littermates. Because Trp(3)-ghrelin is approximately 1/10-1/20 less potent than ghrelin in vivo, plasma Trp(3)-ghrelin concentrations in Tg mice were calculated to have an activity approximately 6-fold greater than that of acylated ghrelin seen in non-Tg mice (85-fold x 1/10-1/20). Tg mice exhibited a normal growth and glucose metabolism in their early life stage. However, 1-yr-old Tg mice demonstrated impaired glucose tolerance and reduced insulin sensitivity. This model will be useful to evaluate the long-term effects of ghrelin or ghrelin analogs. In addition, this technique may be a useful method to generate gain-of-activity models for hormones that require posttranscriptional modifications.
Endocrinology 10/2010; 151(12):5935-40. · 4.46 Impact Factor
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Yoshiyuki Hattori,
Naotetsu Kanamoto,
Kumi Kawano,
Hiroshi Iwakura,
Masakatsu Sone,
Masako Miura,
Akihiro Yasoda,
Naohisa Tamura,
Hiroshi Arai, Takashi Akamizu,
Kazuwa Nakao,
Yoshie Maitani
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ABSTRACT: Adrenal neuroblastoma and pheochromocytoma have the same embryonic origin from neural crest cells and mainly arise from the adrenal medulla. Recently, transgenic mice exhibiting tumors in the bilateral adrenal medulla by the expression of SV40 T-antigen were developed. In this study, we investigated mRNA expression in adrenal tumors of transgenic mice and compared them with human pheochromocytoma by DNA microarray analysis. To compare mouse adrenal tumors and human pheochromacytoma, we found that the expressions of noradrenergic neuron-related genes, including dopa decarboxylase, phenylethanolamine-N-methyltransferase and chromogranin B, were up-regulated in humans but not in mice; however, the expression of neuroblastoma-related genes, including Mycn, paired-like homeobox 2b, gamma-aminobutyric acid A receptor beta3 subunit, islet 1 and kinesin family member 1A, was up-regulated in both species. From the gene expression profiles, the characterization of mouse adrenal tumor, may be similar to that of human adrenal neuroblastoma rather than pheochromacytomas. This mouse model would be a useful tool for the development of anti-cancer drugs and for understanding the etiology of adrenal neuroblastoma.
International Journal of Oncology 09/2010; 37(3):695-705. · 2.40 Impact Factor
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Hiroshi Iwakura,
Yushu Li,
Hiroyuki Ariyasu,
Hiroshi Hosoda,
Naotetsu Kanamoto,
Mika Bando,
Go Yamada,
Kiminori Hosoda,
Kazuwa Nakao,
Kenji Kangawa, Takashi Akamizu
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ABSTRACT: To establish a tool to study ghrelin production and secretion in vitro, we developed a novel ghrelin-producing cell line, MGN3-1 (mouse ghrelinoma 3-1) cells from a gastric ghrelin-producing cell tumor derived from ghrelin-promoter Simian virus 40-T-antigen transgenic mice. MGN3-1 cells preserve three essential characteristics required for the in vitro tool for ghrelin research. First, MGN3-1 cells produce a substantial amount of ghrelin at levels approximately 5000 times higher than that observed in TT cells. Second, MGN3-1 cell expressed two key enzymes for acyl modification and maturation of ghrelin, namely ghrelin O-acyltransferase for acylation and prohormone convertase 1/3 for maturation and the physiological acyl modification and maturation of ghrelin were confirmed. Third, MGN3-1 cells retain physiological regulation of ghrelin secretion, at least in regard to the suppression by somatostatin and insulin, which is well established in in vivo studies. Thus, MGN3-1 cells are the first cell line derived from a gastric ghrelin-producing cell preserving secretion of substantial amounts of ghrelin under physiological regulation. This cell line will be a useful tool for both studying the production and secretion of ghrelin and screening of ghrelin-modulating drugs.
Endocrinology 04/2010; 151(6):2940-5. · 4.46 Impact Factor
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ABSTRACT: Adipose tissue inflammation induced by macrophage infiltration through the MCP-1/CCR2 pathway is considered to play a pivotal role in the development of visceral obesity and insulin resistance. In the present study, therefore, we examined whether pharmacological inhibition of CCR2 is effective against the development of diet-induced metabolic disorders.
C57BL/6 mice were fed a high fat and sucrose diet with or without propagermanium (CCR2 inhibitor, 5 or 50 mg/kg BW/day) for 12 weeks from 6 weeks of age. Then we analyzed lipid and glucose metabolism and tissue inflammation in the liver and adipose tissues along with serum markers in those mice.
Propagermanium treatment slightly decreased body weight gain and visceral fat accumulation in diet-induced obese (DIO) mice. Further, propagermanium suppressed macrophage accumulation and shifted adipose tissue macrophage polarization from the pro-inflammatory (M1) state to anti-inflammatory (M2) state in DIO mice. Expressions of TNF-alpha and MCP-1 mRNA in adipose tissue were reduced by propagermanium treatment, indicating that propagermanim suppressed inflammation in adipose tissue. Propagermanium treatment also ameliorated glucose tolerance, insulin sensitivity, and decreased hepatic triglyceride in DIO mice. Thus, propagermanium improved diet-induced obesity and related metabolic disorders, such as insulin resistance and hepatic steatosis by suppressing inflammation in adipose tissue. Our data indicate that inhibition of CCR2 could improve diet-induced metabolic disorders, and that propagermanium may be a beneficial drug for the treatment of metabolic syndrome.
Journal of atherosclerosis and thrombosis 02/2010; 17(3):219-28. · 2.69 Impact Factor
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Hiroyuki Ariyasu,
Hiroshi Iwakura,
Go Yamada,
Naotetsu Kanamoto,
Mika Bando,
Kenji Kohno,
Takahiro Sato,
Masayasu Kojima,
Kazuwa Nakao,
Kenji Kangawa, Takashi Akamizu
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ABSTRACT: Ghrelin was initially identified as an endogenous ligand for the GH secretagogue receptor. When administrated exogenously, ghrelin stimulates GH release and food intake. Previous reports in ghrelin-null mice, which do not exhibit impaired growth nor appetite, question the physiologic role of ghrelin in the regulation of the GH/IGF-I axis. In this study, we generated a transgenic mouse that expresses human diphtheria toxin (DT) receptor (DTR) cDNA in ghrelin-secretion cells [ghrelin-promoter DTR-transgenic (GPDTR-Tg) mice]. Administration of DT to this mouse ablates ghrelin-secretion cells in a controlled manner. After injection of DT into GPDTR-Tg mice, ghrelin-secreting cells were ablated, and plasma levels of ghrelin were markedly decreased [nontransgenic littermates, 70.6 +/- 10.2 fmol/ml vs. GPDTR-Tg, 5.3 +/- 2.3 fmol/ml]. To elucidate the physiological roles of circulating ghrelin on GH secretion and somatic growth, 3-wk-old GPDTR-Tg mice were treated with DT twice a week for 5 wk. The GH responses to GHRH in male GPDTR-Tg mice were significantly lower than those in wild-type mice at 5 wk of age. However, those were normalized at 8 wk of age. In contrast, in female mice, there was no difference in GH response to GHRH between GPDTR-Tg mice and controls at 5 or 8 wk of age. The gender-dependent differences in response to GHRH were observed in ghrelin-ablated mice. However, GPDTR-Tg mice did not display any decreases in IGF-I levels or any growth retardation. Our results strongly suggest that circulating ghrelin does not play a crucial role in somatic growth.
Endocrinology 02/2010; 151(4):1743-50. · 4.46 Impact Factor
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ABSTRACT: The majority of patients with dyspepsia have no identifiable cause of their disease, leading to a diagnosis of functional dyspepsia (FD). While a number of different factors affect gut activity, components of the nervous and endocrine systems are essential for normal gut function. Communication between the brain and gut occurs via direct neural connections or endocrine signaling events. Ghrelin, a peptide produced by the stomach, affects gastric motility/emptying and secretion, suggesting it may play a pathophysiological role in FD. It is also possible that the functional abnormalities in FD may affect ghrelin production in the stomach. Plasma ghrelin levels are reported to be altered in FD, correlating with FD symptom score. Furthermore, some patients with FD suffer from anorexia with body-weight loss. As ghrelin increases gastric emptying and promotes feeding, ghrelin therapy may be a new approach to the treatment of FD.
International Journal of Peptides 01/2010; 2010.
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Michael-Mark Theil,
Sachiko Miyake,
Miho Mizuno,
Chiharu Tomi,
J Ludovic Croxford,
Hiroshi Hosoda,
Julia Theil,
Stephan von Hörsten,
Hiroaki Yokote,
Asako Chiba,
Youwei Lin,
Shinji Oki, Takashi Akamizu,
Kenji Kangawa,
Takashi Yamamura
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ABSTRACT: Ghrelin is a recently identified gastric hormone that displays strong growth hormone-releasing activity mediated by the growth hormone secretagogue receptor. While this unique endogenous peptide participates in the regulation of energy homeostasis, increases food intake, and decreases energy expenditure, its ability to inhibit the production of proinflammatory cytokines in vitro indicates its role in the regulation of inflammatory process in vivo. Here we examine the effect of exogenous ghrelin on the development of experimental autoimmune encephalomyelitis (EAE), a representative model of multiple sclerosis. In the C57BL/6 mouse model of EAE induced by sensitization to myelin oligodendrocyte glycoprotein 35-55 peptide, we found that alternate-day s.c. injections of ghrelin (5 mug/kg/day) from day 1 to 35 significantly reduced the clinical severity of EAE. The suppression of EAE was accompanied by reduced mRNA levels of proinflammatory cytokines such as TNF-alpha, IL-1beta, and IL-6 in the spinal cord cellular infiltrates and microglia from ghrelin-treated mice at the peak of disease, suggesting the role of ghrelin as an antiinflammatory hormone. Consistently, ghrelin significantly suppressed the production of proinflammatory cytokines in LPS-stimulated microglia in vitro. These results shed light on the new role of ghrelin in the regulation of inflammation with possible implications for management of human diseases.
The Journal of Immunology 09/2009; 183(4):2859-66. · 5.79 Impact Factor
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Hiroshi Iwakura,
Hiroyuki Ariyasu,
Yushu Li,
Naotetsu Kanamoto,
Mika Bando,
Go Yamada,
Hiroshi Hosoda,
Kiminori Hosoda,
Akira Shimatsu,
Kazuwa Nakao,
Kenji Kangawa, Takashi Akamizu
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ABSTRACT: Ghrelin is a stomach-derived peptide that has growth hormone-stimulating and orexigenic activities. Although there have been several reports of ghrelinoma cases, only a few cases have elevated circulating ghrelin levels, hampering the investigation of pathophysiological features of ghrelinoma and chronic effects of ghrelin excess. Furthermore, standard transgenic technique has resulted in desacyl ghrelin production only because of the limited tissue expression of ghrelin O-acyltransferase, which mediates acylation of ghrelin. Accordingly, we attempted to create ghrelin promoter SV40 T-antigen transgenic (GP-Tag Tg) mice, in which ghrelin-producing cells continued to proliferate and finally developed into ghrelinoma. Adult GP-Tag Tg mice showed elevated plasma ghrelin levels with preserved physiological regulation. Adult GP-Tag Tg mice with increased plasma ghrelin levels exhibited elevated IGF-I levels despite poor nutrition. Although basal growth hormone levels were not changed, those after growth hormone-releasing hormone injection tended to be higher. These results indicate that chronic elevation of ghrelin activates GH-IGF-I axis. In addition, GP-Tag Tg mice demonstrated glucose intolerance. Insulin secretion by glucose tolerance tests was significantly attenuated in GP-Tag Tg, whereas insulin sensitivity determined by insulin tolerance tests was preserved, indicating that chronic elevation of ghrelin suppresses insulin secretion and leads to glucose intorelance. Thus, we successfully generated a Tg model of ghrelinoma, which is a good tool to investigate chronic effects of ghrelin excess. Moreover, their characteristic features could be a hint on ghrelinoma.
AJP Endocrinology and Metabolism 08/2009; 297(3):E802-11. · 4.75 Impact Factor
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ABSTRACT: Neuroblastoma is the most common childhood cancer, which arises from sympathetic neural precursors. Because the prognosis of advanced neuroblastoma is known to be poor, developments of new anti-cancer drugs are desperately needed. For screening of therapeutic drugs for neuroblastoma, genetically engineered animal models would be useful. In an attempt to obtain transgenic mice carrying simian virus 40 T-antigen gene under control of tetracycline responsive elements with cytomegalovirus promoter, we found one line of mice exhibiting bilateral adrenal tumors by leakage expression of T-antigen in adrenal gland. These adrenal tumors contained small round tumor cells with increased N/C ratio, showing chromogranin A and neuron specific enolase-like immunoreactivity. By electron microscopy, tumor cells containing neuritic processes with synaptic vesicles surrounding them were observed. The plasma levels of dopamine were significantly elevated in these transgenic mice. MYCN expression levels were significantly elevated in these tumors. These findings indicated that the adrenal tumor was a neuroblastoma. This mouse model would be a useful tool for development of chemotherapeutic drugs and understanding the etiology of neuroblastoma.
International Journal of Oncology 01/2009; 33(6):1195-9. · 2.40 Impact Factor
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Takashi Akamizu,
Hiroshi Iwakura,
Hiroyuki Ariyasu,
Toshinori Murayama,
Eriko Sumi,
Satoshi Teramukai,
Koji Goto,
Eijiro Ohnishi,
Haruhiko Akiyama,
Keiichi Kawanabe,
Manabu Nankaku,
Noriaki Ichihashi,
Tadao Tsuboyama,
Ken Tamai,
Masako Kataoka,
Takashi Nakamura,
Kenji Kangawa
Journal of the American Geriatrics Society 01/2009; 56(12):2363-5. · 3.74 Impact Factor
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Ken-ichi Takahashi,
Kazuo Chin, Takashi Akamizu,
Satoshi Morita,
Kensuke Sumi,
Toru Oga,
Hisako Matsumoto,
Akio Niimi,
Tomomasa Tsuboi,
Shunichi Fukuhara,
Kenji Kangawa,
Michiaki Mishima
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ABSTRACT: Patients with newly diagnosed OSA have been reported to have recent weight gain prior to diagnosis. Ghrelin stimulates food intake and increases weight gain. Plasma ghrelin is decreased in obese and increased in lean individuals. Of the two circulating forms of ghrelin, acylated and unacylated, the former is thought to be essential for the biological activity of ghrelin.
The plasma levels of the two forms of ghrelin were measured in 21 OSA patients (with a mean of 46.2 sleep-disordered events/h) before and after 1 month of nasal CPAP (nCPAP) treatment, and were compared with those in 14 untreated OSA patients and 13 individuals without OSA.
The BMI was significantly higher in the 21 OSA patients than in the non-OSA group as were the baseline acylated (11.4 +/- 5.86 vs 7.19 +/- 3.80 fmol/mL, P = 0.03) and unacylated (84.2 +/- 50.6 vs 48.3 +/- 23.2 fmol/mL, P = 0.02) ghrelin levels. The total ghrelin level was positively correlated with the number of sleep-disordered breathings (P = 0.002). After 1 month of nCPAP treatment, the acylated ghrelin level significantly decreased (P = 0.02) while the unacylated ghrelin level did not (P = 0.09).
Treatment of OSA may play an important role in the management of obesity in these patients by reducing the acylated ghrelin level.
Respirology 12/2008; 13(6):810-6. · 2.42 Impact Factor
