[Show abstract][Hide abstract] ABSTRACT: Cisplatin is a highly effective chemotherapeutic agent used to treat various malignancies, but its utility is compromised by its nephrotoxicity. C-type natriuretic peptide (CNP), a member of the natriuretic peptide family, exhibits anti-inflammatory effects by activating its specific receptor, guanylyl cyclase (GC)-B. CNP and GC-B receptor are known to be expressed in both the vascular endothelium and the kidney. The objective of this study was to investigate the renoprotective effects of CNP in a mouse model of cisplatin-induced nephrotoxicity.
C57BL/6 mice were divided into three groups: normal control mice; cisplatin (20 mg/kg, intraperitoneal) mice treated with vehicle; and cisplatin mice treated with CNP (2.5 µg/kg/min, subcutaneous). At 72 h after cisplatin injection, urine, blood and kidney samples were collected. Urine and blood samples were examined biochemically. Histological findings and gene expression in kidney tissue were evaluated.
CNP reduced histological renal tubular damage and apoptosis induced by cisplatin and suppressed plasma blood urea nitrogen and creatinine levels, which were elevated by cisplatin administration. CNP treatment decreased the expression of kidney injury molecule-1 and monocyte chemoattractant protein-1, which were elevated in the kidney by cisplatin administration. CNP treatment attenuated the decrease in GC-B expression in cisplatin-induced kidney injury.
The present study is the first to show that CNP inhibits nephrotoxicity and kidney cell damage induced by cisplatin. The mechanism of action may involve down-regulation of inflammatory cytokine expression in cisplatin-induced kidney injury and attenuation of apoptosis in renal tubular cells.
Cancer Chemotherapy and Pharmacology 03/2015; 75(5). DOI:10.1007/s00280-015-2734-7 · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Most patients suffering from cancer die of metastatic disease. Surgical removal of solid tumors is performed as an initial attempt to cure patients; however, surgery is often accompanied with trauma, which can promote early recurrence by provoking detachment of tumor cells into the blood stream or inducing systemic inflammation or both. We have previously reported that administration of atrial natriuretic peptide (ANP) during the perioperative period reduces inflammatory response and has a prophylactic effect on postoperative cardiopulmonary complications in lung cancer surgery. Here we demonstrate that cancer recurrence after curative surgery was significantly lower in ANP-treated patients than in control patients (surgery alone). ANP is known to bind specifically to NPR1 [also called guanylyl cyclase-A (GC-A) receptor]. In mouse models, we found that metastasis of GC-A-nonexpressing tumor cells (i.e., B16 mouse melanoma cells) to the lung was increased in vascular endothelium-specific GC-A knockout mice and decreased in vascular endothelium-specific GC-A transgenic mice compared with control mice. We examined the effect of ANP on tumor metastasis in mice treated with lipopolysaccharide, which mimics systemic inflammation induced by surgical stress. ANP inhibited the adhesion of cancer cells to pulmonary arterial and micro-vascular endothelial cells by suppressing the E-selectin expression that is promoted by inflammation. These results suggest that ANP prevents cancer metastasis by inhibiting the adhesion of tumor cells to inflamed endothelial cells.
Proceedings of the National Academy of Sciences 03/2015; 112(13). DOI:10.1073/pnas.1417273112 · 9.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neuromedin U (NMU) and S (NMS) display various physiological activities, including an anorexigenic effect, and share a common C-terminal heptapeptide-amide sequence that is necessary to activate two NMU receptors (NMUR1 and NMUR2). On the basis of this knowledge, we recently developed hexapeptide agonists 2 and 3, which are highly selective to human NMUR1 and NMUR2, respectively. However, the agonists are still less potent than the endogenous ligand, hNMU. Therefore, we performed an additional structure-activity relationship study, which led to the identification of the more potent hexapeptide 5d that exhibits similar NMUR1-agonistic activity as compared to hNMU. Additionally, we studied the stability of synthesized agonists, including 5d, in rat serum, and identified two major biodegradation sites: Phe(2)-Arg(3) and Arg(5)-Asn(6). The latter was more predominantly cleaved than the former. Moreover, substitution with 4-fluorophenylalanine, as in 5d, enhanced the metabolic stability at Phe(2)-Arg(3). These results provide important information to guide the development of practical hNMU agonists.
[Show abstract][Hide abstract] ABSTRACT: Cisplatin is an effective chemotherapeutic agent used in the treatment of a wide variety of malignancies. Acute kidney injury (AKI) is the major toxicity associated with cisplatin and sometimes necessitates a reduction in dose or discontinuation of treatment. Atrial natriuretic peptide (ANP) is secreted by the heart and exerts a wide range of renoprotective effects, including anti-inflammatory activity. The objective of this study was to investigate the protective effects of ANP on cisplatin-induced AKI in mice.
Cancer Chemotherapy and Pharmacology 11/2014; 75(1). DOI:10.1007/s00280-014-2624-4 · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intrauterine growth retardation (IUGR) occurs in 3–7% of all pregnancies. Recent human studies have indicated that neurodevelopmental disabilities, learning disorders, memory impairment, and mood disturbance are common in IUGR offspring. However, the interactions between IUGR and neurodevelopmental disorders are unclear because of the wide range of causes of IUGR, such as maternal malnutrition, placental insufficiency, pregnancy toxemia, and fetal malformations. Meanwhile, many studies have shown that moderate food restriction enhances spatial learning and improves mood disturbance in adult humans and animals. To date, the effects of maternal moderate food restriction on fetal brain remain largely unknown. In this study, we hypothesized that IUGR would be caused by even moderate food restriction in pregnant females, and that the offspring would have neurodevelopmental disabilities. Mid-pregnant mice received moderate food restriction through the early lactation period. The offspring were tested for aspects of physical development, behavior, and neurodevelopment. The results showed that moderate maternal food restriction induced IUGR. Offspring had low birth weight and delayed development of physical and coordinated movement. Moreover, IUGR offspring exhibited mental disabilities such as anxiety and poor cognitive function. In particular, male offspring exhibited significantly impaired cognitive function at 3 weeks of age. These results suggested that a restricted maternal diet could be a risk factor for developmental disability in IUGR offspring, and that male offspring might be especially susceptible.
Nutrition Research 11/2014; 35(1). DOI:10.1016/j.nutres.2014.10.014 · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We identified two ghrelin receptor isoforms, the ghrelin receptor type-1a (GHS-R1a) and its alternative splice form (GHS-R1b) for West African lungfish, Protopterus annectens. Lungfish GHS-R1a and 1b comprised 361 and 281 amino acids, respectively. Lungfish GHS-R1a showed the highest identity to coelacanth GHS-R1a (80.4%). The highest expression of GHS-R1a mRNAs was seen in the brain, liver, ovary, heart, intestine, and gills. GHS-R1b mRNAs were also detected in the same tissues with GHS-R1a, but their expression level was 1/20 that of GHS-R1a. In human embryonic kidney 293 cells transiently expressing lungfish GHS-R1a, rat and bullfrog ghrelin, and two GHS-R1a agonists, GHRP-6 and hexarelin, increased intracellular Ca(2+) concentrations. The intensity of the Ca(2+) increases induced by GHS-R1a agonists was twice when compared to that induced by ghrelin, although the median effective doses (ED50) were similar, suggesting a long-lasting effect of GHS-R1a agonists with similar affinity. We also examined changes in the GHS-R gene expression during an eight-week estivation. Body weight was slightly lowered, but plasma sodium and glucose concentrations decreased; plasma urea concentration increased significantly 4 weeks after the start of estivation. Overall, expression of GHS-R1a mRNA decreased, but changes in GHS-R1b mRNA expression were inconsistent with those of GHS-R1a during estivation, suggesting an involvement of GHS-R in energy homeostasis, as seen in mammals. Our results suggest that the ghrelin-GHS-R1a system is present in this lungfish although ghrelin has not yet been found. The structure of GHS-R1a is closer to that of tetrapods than Actinopterygian fish, indicating a process of evolution that follows the Crossopterygii such as coelacanth.
General and Comparative Endocrinology 08/2014; 209. DOI:10.1016/j.ygcen.2014.07.021 · 2.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neuromedin U (NMU) are bioactive peptides with a common C-terminal heptapeptide-sequence (FLFRPRN-amide, 1a) among mammals, which is responsible for receptor activation, namely NMU receptors types 1 (NMUR1) and 2 (NMUR2). Among the various physiological actions of NMU, the anorexigenic effect has recently attracted attention in drug discovery efforts for treating obesity. Although several structure-activity relationship (SAR) studies have been reported, receptor-selective small peptide agonists have yet to be disclosed. Herein an SAR study of 1a-derived peptide derivatives is described. We initially screened both human NMUR1 and NMUR2 selective peptides in calcium-mobilization assays with cells transiently expressing receptors. Then we performed a precise assay with a stable expression system of receptors, and consequently discovered hexapeptides 8d and 6b possessing selective agonist activity towards each respective receptor. Hexapeptide 6b, which selectively activates NMUR2 without significant NMUR1 activation, should aid in the development of anorexigenic drugs as well as advance NMU-related endocrinological research.
[Show abstract][Hide abstract] ABSTRACT: Background and purpose
Most therapeutic agents are administered intravenously (IV) in clinical settings and intraperitoneally (IP) in preclinical studies with neonatal rodents; however, it remains unclear whether intraperitoneal (IP) injection is truly an acceptable alternative for intravenous (IV) injection in preclinical studies. The objective of our study is to clarify the differences in the therapeutic effects of drugs and in the distribution of infused cells after an IP or IV injection in animals with brain injury.
Dexamethasone or MK-801, an N-methyl-d-aspartate receptor antagonist was administered either IP or IV in a mouse model of neonatal hypoxic–ischemic encephalopathy. Green fluorescent protein-expressing mesenchymal stem cells (MSCs) or mononuclear cells (MNCs) were injected IP or IV in the mouse model. Two hours and 24 h after the administration of the cells, we investigated the cell distributions by immunohistochemical staining. We also investigated distribution of IV administered MNCs labeled with 2-[18F]fluoro-2-deoxy-d-glucose in a juvenile primate, a macaque with stroke 1 h after the administration.
IP and IV administration of dexamethasone attenuated the brain injury to a similar degree. IP administration of MK-801 attenuated brain injury, whereas IV administration of MK-801 did not. The IV group showed a significantly greater number of infused cells in the lungs and brains in the MSC cohort and in the spleen, liver, and lung in the MNC cohort compared to the IP group. In the macaque, MNCs were detected in the spleen and liver in large amounts, but not in the brain and lungs.
This study demonstrated that the administration route influences the effects of drugs and cell distribution. Therefore, a preclinical study may need to be performed using the optimal administration route used in a clinical setting.
Brain and Development 07/2014; 37(4). DOI:10.1016/j.braindev.2014.06.010 · 1.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Both hexarelin and its natural analog ghrelin exert comparable cardioprotective activities. A single dose of ghrelin administered at the very acute phase after experimental myocardial infarction positively affects cardiac function in chronic heart failure. Therefore, this study aimed to determine whether a single dose of oral hexarelin has the same effect in the chronic disease phase. Myocardial infarction or sham operation was generated by left coronary artery ligation in male C57BL/6J mice, which subsequently received one dose of hexarelin or vehicle treatment by oral gavage 30minutes after operation. Although the mortality within 14 days after myocardial infarction did not differ between the groups, hexarelin treatment protected cardiac function in the chronic phase as evidenced by higher ejection fraction and fractional shortening, as well as lower lung weight/body weight and lung weight/tibial length ratios, compared with vehicle treatment. Hexarelin treatment concurrently lowered plasma epinephrine and dopamine levels, and shifted the balance of autonomic nervous activity toward parasympathetic nervous activity as evidenced by a smaller low/high-frequency power ratio and larger normalized high-frequency power on heart rate variability analysis. The results first demonstrate that one dose of oral hexarelin treatment potentially protects chronic cardiac function after acute myocardial infarction, and implicate that activating growth hormone secretagogue receptor 1a might be beneficial for cardioprotection, although other mechanism may also be involved.
[Show abstract][Hide abstract] ABSTRACT: We recently reported that administration of atrial natriuretic peptide during the perioperative period has prophylactic effects with respect to not only cardiovascular but also respiratory complications following pulmonary resection. However, its mechanisms are not well understood. The objective of the present study was to investigate the mechanism of the prophylactic effects of atrial natriuretic peptide in an acute lung injury model.
For the evaluation of the early phase of pulmonary inflammation, in vitro and in vivo studies using lipopolysaccharide were used. In the in vitro study, the effects of atrial natriuretic peptide on the induction of E-selectin by lipopolysaccharide in human pulmonary artery endothelial cells were evaluated. In the in vivo study, the effects of atrial natriuretic peptide on lipopolysaccharide-induced inflammatory cell infiltration and cytokine levels including tumor necrosis factor-alpha and interleukin-6 in the bronchoalveolar lavage fluid in the lungs of C57/B6 mice were examined. The number of myeloperoxidase-positive staining cells in the tissue sections of the lung of lipopolysaccharide-administered C57/B6 mice was also evaluated.
Atrial natriuretic peptide significantly attenuated the up-regulation of E-selectin expression induced by lipopolysaccharide in human pulmonary artery endothelial cells. There were significantly lower cell counts and levels of tumor necrosis factor-alpha and interleukin-6 in the bronchoalveolar lavage fluid of atrial natriuretic peptide-treated mice compared to control mice after lipopolysaccharide injection. In addition, there were significantly fewer myeloperoxidase-positive cells in atrial natriuretic peptide-treated mice than in control mice after lipopolysaccharide injection.
Atrial natriuretic peptide had a protective effect in the lipopolysaccharide-induced acute lung injury model. Atrial natriuretic peptide may be of value in therapeutic strategies aimed at the treatment of acute lung injury such as pneumonia or acute respiratory distress syndrome.
[Show abstract][Hide abstract] ABSTRACT: Both hexarelin and its natural analog ghrelin exert comparable cardioprotective activities. A single dose of ghrelin administered at the very acute phase after experimental myocardial infarction positively affects cardiac function in chronic heart failure. Therefore, this study aimed to determine whether a single dose of oral hexarelin has the same effect in the chronic disease phase. Myocardial infarction or sham operation was generated by left coronary artery ligation in male C57BL/6J mice, which subsequently received one dose of hexarelin or vehicle treatment by oral gavage 30 min after operation. Although the mortality within 14 days after myocardial infarction did not differ between the groups, hexarelin treatment protected cardiac function in the chronic phase as evidenced by higher ejection fraction and fractional shortening, as well as lower lung weight/body weight and lung weight/tibial length ratios, compared with vehicle treatment. Hexarelin treatment concurrently lowered plasma epinephrine and dopamine levels, and shifted the balance of autonomic nervous activity toward parasympathetic nervous activity as evidenced by a smaller low/high-frequency power ratio and larger normalized high-frequency power on heart rate variability analysis. The results first demonstrate that one dose of oral hexarelin treatment potentially protects chronic cardiac function after acute myocardial infarction, and implicate that activating growth hormone secretagogue receptor 1a might be beneficial for cardioprotection, although other mechanism may also be involved.
[Show abstract][Hide abstract] ABSTRACT: After the discovery in 1996 of the growth hormone secretagogue-receptor type-1a (GHS-R1a) as an orphan G-protein coupled receptor, many research groups attempted to identify the endogenous ligand. Finally, Kojima and colleagues successfully isolated the peptide ligand from rat stomach extracts, determined its structure, and named it ghrelin (Kojima et al. 1999). The GHS-R1a is now accepted to be the ghrelin receptor. The existence of the ghrelin system has been demonstrated in many animal classes through biochemical and molecular biological strategies as well as through genome projects. Our work, which has concentrated on identifying the ghrelin receptor and its ligand ghrelin in laboratory animals, particularly non-mammalian vertebrates, has provided new insights into the molecular evolution of the ghrelin receptor. In mammals, it is assumed that the ghrelin receptor evolution is in line with the plate tectonics theory. In contrast, the evolution of the ghrelin receptor in non-mammalian vertebrates differs from that of mammals: multiplicity of the ghrelin receptor isoforms is observed in non-mammalian vertebrates only. This multiplicity is due to genome duplication and polyploidization events that particularly occurred in Teleostei. Furthermore, it is likely that the evolution of the ghrelin receptor is distinct from that of its ligand, ghrelin, since only one ghrelin isoform has been detected in all species examined so far. In this review, we summarize current knowledge related to the molecular evolution of the ghrelin receptor in mammalian and non-mammalian vertebrates.