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Biomedical subjects

Kenji Kangawa

Publications and source records attributed to Kenji Kangawa.

At least 145 records · Page 8Linked to original sources
PubMed2004

Pharmacokinetics, safety, and endocrine and appetite effects of ghrelin administration in young healthy subjects.

OBJECTIVE: It has been demonstrated that ghrelin plays a major role in the regulation of GH secretion and food intake. These actions make ghrelin a strong candidate for the treatment of GH deficiency, anorexia and cachexia. However, only preliminary studies have been performed to assess ghrelin administration in humans. In this study, we have conducted a double-blind, randomized, placebo-controlled trial to investigate the pharmacokinetics, safety, and endocrine and appetite effects of ghrelin in young healthy volunteers. DESIGN: Eighteen male volunteers were randomly assigned into three groups of six subjects: low- and high-dose ghrelin groups, who received intravenous injections of 1 and 5 microg/kg ghrelin (acylated form) respectively, and a placebo group who were injected with mannitol instead of ghrelin. RESULTS: Acylated ghrelin disappeared more rapidly from plasma than total ghrelin, with elimination half life (t(1/2)) of 9-13 and 27-31 min respectively. The number of subjects that experienced adverse effects did not significantly differ among the three groups, and all adverse effects were transient and well tolerated. Both the low and high doses of ghrelin strongly stimulated GH release (peak plasma concentration (C(max,0-90 min)): 124.2+/-63.9 and 153.2+/-52.2 ng/ml for 1 and 5 microg/kg ghrelin respectively). Slight alterations of blood glucose and insulin levels after the injection were observed. Although not statistically significant, ghrelin administration tended to increase hunger sensation in a dose-dependent manner. CONCLUSIONS: These results suggest that ghrelin is safe, and that clinical trials may be started to assess the usefulness of ghrelin for the treatment of disorders related to GH secretion and appetite.

Adult↗
PubMed2004

Intravenous administration of ghrelin stimulates growth hormone secretion in vagotomized patients as well as normal subjects.

OBJECTIVE: Ghrelin is a potent peptide stimulating GH secretion. Besides its direct action on the pituitary, ghrelin has been reported to stimulate GH release via the vagal afferent nerve in rats. To examine the involvement of vagal nerve in ghrelin-induced GH secretion in humans, GH responses to ghrelin were compared between vagotomized patients with gastrectomy and normal subjects. METHODS: Ghrelin (0.2 microg/kg) or GHRH (1 microg/kg) was administered intravenously in vagotomized patients and normal subjects on separate days, and plasma GH responses to the stimuli were examined. RESULTS: Ghrelin caused a significant plasma GH rise in both vagotomized patients and normal subjects. Peak GH levels in vagotomized patients (37.5+/-16.9 ng/ml) were not different from those in normal subjects (29.9+/-23.1 ng/ml). The areas under the curve of GH response to ghrelin did not differ between the two groups. GHRH also increased GH levels, and peak GH levels and areas under the curve after GHRH stimulation were also comparable between vagotomized patients and normal subjects. CONCLUSIONS: In the present study, the involvement of the afferent vagal nerve in ghrelin-induced GH secretion was not confirmed in humans.

Adult↗
PubMed2004

Localization of ghrelin-producing cells in the stomach of the rainbow trout (Oncorhynchus mykiss).

Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor (GHS-R), was isolated from the rat stomach and determined to be n-octanoylated 28-amino-acid peptide. In this study, we studied the distribution of ghrelin-producing cells (ghrelin cells) in the gastrointestinal tract of male and female rainbow trout (Oncorhynchus mykiss) by immunohistochemistry using N-terminal region-recognizing antibody and also by in situ hybridization using a trout ghrelin-specific cRNA probe. Ghrelin cells were found in the mucosal layer of the stomach but not in the myenteric plexus, and no ghrelin cells were observed in other regions of the gastrointestinal tract. Ghrelin cells could be classified into two types: closed- and opened-type cells. The density of ghrelin cells increased gradually in the direction from the cardiac to pyloric portions of the stomach in both sexes. The number of ghrelin cells per unit area seemed to be higher in females than in males. In conclusion, trout ghrelin cells exist in the stomach and are classified into two types of cells, closed- and opened-type cells.

Animals↗
PubMed2004

Endogenous ghrelin in pancreatic islets restricts insulin release by attenuating Ca2+ signaling in beta-cells: implication in the glycemic control in rodents.

Ghrelin, isolated from the human and rat stomach, is the endogenous ligand for the growth hormone (GH) secretagogue receptor, which is expressed in a variety of tissues, including the pancreatic islets. It has been shown that low plasma ghrelin levels correlates with elevated fasting insulin levels and type 2 diabetes. Here we show a physiological role of endogenous ghrelin in the regulation of insulin release and blood glucose in rodents. Acylated ghrelin, the active form of the peptide, was detected in the pancreatic islets. Counteraction of endogenous ghrelin by intraperitoneal injection of specific GH secretagogue receptor antagonists markedly lowered fasting glucose concentrations, attenuated plasma glucose elevation, and enhanced insulin responses during the glucose tolerance test (GTT). Conversely, intraperitoneal exogenous ghrelin GH-independently elevated fasting glucose concentrations, enhanced plasma glucose elevation, and attenuated insulin responses during GTT. Neither GH secretagogue receptor antagonist nor ghrelin affected the profiles of the insulin tolerance test. In isolated islets, GH secretagogue receptor blockade and antiserum against acylated ghrelin markedly enhanced glucose-induced increases in insulin release and intracellular Ca2+ concentration ([Ca2+]i), whereas ghrelin at a relatively high concentration (10 nmol/l) suppressed insulin release. In single beta-cells, ghrelin attenuated glucose-induced first-phase and oscillatory [Ca2+]i increases via the GH secretagogue receptor and in a pertussis toxin-sensitive manner. Ghrelin also increased tetraethylammonium-sensitive delayed outward K+ currents in single beta-cells. These findings reveal that endogenous ghrelin in islets acts on beta-cells to restrict glucose-induced insulin release at least partly via attenuation of Ca2+ signaling, and that this insulinostatic action may be implicated in the upward control of blood glucose. This function of ghrelin, together with inducing GH release and feeding, suggests that ghrelin underlies the integrative regulation of energy homeostasis.

Animals↗
PubMed2004

Diagnostic and prognostic value of plasma brain natriuretic peptide in non-dialysis-dependent CRF.

BACKGROUND: Brain natriuretic peptide (BNP) is useful for the evaluation of ventricular dysfunction in patients with various cardiac diseases. However, its diagnostic value has been considered to be limited in patients with chronic renal failure (CRF) because renal dysfunction itself may affect BNP levels. This study is designed to clarify the diagnostic and prognostic value of plasma BNP level in patients with CRF. METHODS: In 103 non-dialysis-dependent patients with CRF without heart failure and 60 hypertensive patients with normal renal function, echocardiographic examinations and BNP measurements were performed. RESULTS: Plasma BNP level was much greater in patients with CRF than in hypertensive controls; however, multiple regression analysis showed that left ventricular (LV) end-diastolic volume (EDV) index (LVEDVI) and the difference in mitral and pulmonary venous atrial wave duration (Ad-PVad), a marker of LV end-diastolic pressure, were independent determinants of plasma BNP levels in patients with CRF. The influence of LV overload (LVEDVI > or = 75 mL/m 2 and/or Ad-PVad < 0 milliseconds) on plasma BNP levels in subjects with CRF was independent of the severity of renal dysfunction. From Kaplan-Meier event-free curves (mean follow-up, 13 months), the incidence of heart failure was much greater in patients with a plasma BNP level of 150 pg/mL or greater ( P < 0.001). By means of multivariate Cox regression analysis, high plasma BNP level was the strongest predictor for heart failure events (hazard ratio, 6.31; P < 0.001). CONCLUSION: These findings support plasma BNP level as a reliable marker of LV overload, even in nondialysis patients with CRF. Also, a high BNP level (> or =150 pg/mL) may have powerful predictive potential for heart failure in these patients.

Aged↗