Biomedical subjects

Kenji Kangawa

Publications and source records attributed to Kenji Kangawa.

239 records · Page 14Linked to original sources

PubMed2002

Fasting plasma ghrelin levels are negatively correlated with insulin resistance and PAI-1, but not with leptin, in obese children and adolescents.

Ghrelin is a novel growth hormone-releasing peptide isolated from human and rat stomach that induces weight gain by increasing food intake and reducing fat utilization. Although recent data indicate that ghrelin is downregulated in human adult obesity, the characteristics of human obesity are heterogeneous, especially in children and adolescents, and depend on the distribution of subcutaneous and visceral fat tissue. We measured fasting plasma ghrelin concentrations by radioimmunoassay in 49 obese Japanese children and adolescents (38 boys and 11 girls; mean age 10.2 +/- 2.8 years; BMI 28.0 +/- 4.5 kg/m(2), percent overweight 56.0 +/- 20.7%), and analyzed associations of their ghrelin concentrations with their body composition, insulin resistance, and adipocytokine concentrations. Fasting plasma ghrelin levels were negatively correlated with BMI and waist circumference, but not with percent overweight or percent body fat, whereas fasting leptin levels were positively correlated with all of the following parameters: BMI, waist circumference, percent overweight, and percent body fat. Plasma ghrelin levels were negatively correlated with fasting immunoreactive insulin, homeostasis model assessment insulin resistance index, and quantitative insulin sensitivity check index values. There was no correlation between plasma ghrelin and leptin, but ghrelin was negatively correlated with the PAI-1 concentrations. The results suggest that the downregulation of ghrelin secretion may be a consequence of higher insulin resistance associated with visceral fat accumulation and elevated PAI-1 concentrations, and not a consequence of total body fat accumulation associated with elevated leptin concentrations.

Adolescent↗

PubMed2001

Ghrelin modulates the downstream molecules of insulin signaling in hepatoma cells.

Ghrelin was identified in the stomach as an endogenous ligand specific for the growth hormone secretagogue receptor (GHS-R). GHS-R is found in various tissues, but its function is unknown. Here we show that GHS-R is found in hepatoma cells. Exposure of these cells to ghrelin caused up-regulation of several insulin-induced activities including tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1), association of the adapter molecule growth factor receptor-bound protein 2 with IRS-1, mitogen-activated protein kinase activity, and cell proliferation. Unlike insulin, ghrelin inhibited Akt kinase activity as well as up-regulated gluconeogenesis. These findings raise the possibility that ghrelin modulates insulin activities in humans.

Animals↗

PubMedDate not supplied

Pulmonary vascular reactivity of spontaneously hypertensive rats is exacerbated in response to the central administration of exogenous nitric oxide.

1. Centrally, nitric oxide (NO) is a sympathoinhibitory substance. Spontaneously hypertensive rats (SHR) have an impaired central nitroxidergic system and, consequently, NO-mediated decrease in sympathetic activity is exacerbated in SHR compared with Wistar-Kyoto (WKY) rats. We have demonstrated previously that acute hypoxic pulmonary vasoconstriction (HPV) is enhanced by central NO administration. Therefore, in the present study, we hypothesized that accentuation of the HPV by NO would be exacerbated in SHR compared with WKY rats. 2. Mean pulmonary arterial pressure, systemic mean arterial blood pressure, cardiac output and heart rate were measured in pentobarbitone-anaesthetized, artificially ventilated, male SHR and WKY rats. The brief, transient response to a bolus intracerebroventricular (i.c.v.) dose of N(G)-nitro-L-arginine methyl ester (L-NAME; 150 microg in 10 microL) was recorded in all rats. Upon recovery, rats were exposed to acute hypoxia (10% O(2) for 4 min) before and after the i.c.v. administration of the NO donor 3-[4-morpholinyl]-sydnonimine-hydrochloride (SIN-1; 100 microg in 10 microL). 3. In WKY rats, central inhibition of NO synthesis by L-NAME caused a mild increase in tonic pulmonary vascular tone and induced a large systemic pressor response. These responses were not observed in SHR. In contrast, SIN-1 failed to alter tonic pulmonary vascular tone, although it enhanced the HPV in WKY rats and, significantly more so, in SHR. 4. These results confirm that accentuation of the HPV by NO is exacerbated in SHR compared with WKY rats. The mechanism(s) by which the HPV is accentuated by central NO remains to be fully elucidated, but is likely to be associated with the sympathoinhibitory effects of NO and, if so, supports the idea that the nitroxidergic system of the SHR is impaired. Further electrophysiological studies are essential to confirm these assumptions.

Animals↗

PubMedDate not supplied

Plasma ghrelin concentration correlates with the levels of serum pepsinogen I and pepsinogen I/II ratio--a possible novel and non-invasive marker for gastric atrophy.

BACKGROUND/AIMS: Ghrelin, a novel growth-hormone-releasing peptide, has been reported to be localized mainly in the A-like cells in the gastric fundic mucosa. With the extension of gastric inflammation caused by H. pylori infection, gastric mucosal atrophy extends from the antrum to the corpus, which is the predominant site of localization of the ghrelin-producing A-like cells. The present study was designed to investigate the correlation between the plasma ghrelin levels and the extent of gastric mucosal atrophy in patients with chronic gastritis caused by H. pylori infection. METHODOLOGY: Sixty-nine patients with dyspeptic symptoms were enrolled for the study. Of these, 41 patients were confirmed to become negative for H. pylori after therapy to eradicate the infection. The other 28 patients were diagnosed as positive for H. pylori infection. Blood samples were collected from all the patients after 12 hours of fasting, before upper gastrointestinal endoscopy was performed. The plasma levels of total and active ghrelin, as well as the serum levels of pepsinogen I (PGI) and pepsinogen II (PGII) were measured by radioimmunoassay. Based on endoscopic assessment, the atrophic changes in the gastric mucosa were classified as open-type atrophy or closed-type atrophy. RESULTS: There were no significant differences in the plasma total and active ghrelin levels between H. pylori-positive and H. pylori-eradicated (negative) patients. The serum levels of PGI correlated well with the plasma levels of total ghrelin (p<0.01, r=0.38) and active ghrelin (p<0.05, r=0.29). The ratio of serum PGI to PGII level (PG I/II ratio) also correlated well with the plasma level of total ghrelin (p<0.05. r=0.31) and active ghrelin (p<0.05, r=0.27). The plasma levels of total as well as active ghrelin were significantly decreased in patients with low PG levels as compared with those in patients with high PG levels (PGI > 70 ng/mL or PGI/II >3.0). The plasma levels of total as well as active ghrelin were also significantly decreased in patients with endoscopically diagnosed open-type atrophy as compared with those in patients with endoscopically diagnosed closed-type atrophy (p < 0.01), especially in the H. pylori-eradicated cohorts. CONCLUSIONS: The plasma levels of ghrelin, which correlated well with the serum levels of PGI as well as the PGI/II ratio, decreased with increasing extent of gastric mucosal atrophy, suggesting that it could be a potentially useful non-invasive marker for chronic atrophic gastritis.

Biomarkers↗

PubMedDate not supplied

Long-term strict monitoring of plasma ghrelin and other serological markers of gastric diseases after Helicobacter pylori eradication.

We report on a case of chronic atrophic gastritis in which the serological markers of gastric diseases were strictly monitored for 2 years after successful Helicobacter pylori (H. pylori) eradication. A 31-year-old man with upper abdominal pain was diagnosed as having H. pylori infection. Laboratory examination revealed low serum levels of pepsinogen (PG) I, low PG I/II ratio, and low plasma levels of ghrelin. Upper gastrointestinal endoscopy revealed severe corpus-dominant atrophic gastritis. H. pylori eradication therapy was performed. Successful eradication was confirmed three months later by the 13C urea breath test. Decreased serum PG II levels and an increased serum PG I/II ratio were detected a week after completion of the eradication therapy. The serum anti-H. pylori IgG titer decreased to less than 75% of the baseline level by 24 weeks after completion of the eradication therapy. On the other hand, the plasma levels of total and active ghrelin showed no marked changes after successful eradication therapy. This is the first report of long-term follow-up of changes of the plasma ghrelin levels after H. pylori eradication therapy, the observations suggesting that reduction of plasma ghrelin levels cannot be achieved merely by H. pylori eradication, without resolution of the gastric atrophy.

Adult↗