Mari Murashita

Olanzapine increases plasma ghrelin level in patients with schizophrenia

OBJECTIVE Increased appetite and weight gain are frequently reported in treatment with olanzapine. However, the mechanism behind this appetite gain remains unclear. Ghrelin is a newly discovered appetite-stimulating peptide that has a role in the regulation of feeding behavior. Ghrelin is synthesized principally in the stomach, and the concentration of circulating ghrelin is negatively correlated with leptin and body fat mass. To elucidate the mechanism of appetite and weight gain during olanzapine treatment, we investigated the circulating ghrelin levels. METHODS Seven patients with schizophrenia were examined before and after 6-month administration of olanzapine. The concentrations of circulating ghrelin, leptin, glucose and lipid metabolic parameters were measured. RESULTS Body fat percentage (P=0.0121) and serum leptin (P=0.0284) were significantly increased after 6-month administration of olanzapine. Both plasma total ghrelin (P=0.0188) and active ghrelin levels (P=0.0057) were significantly increased. Six of the seven patients reported increased appetite during olanzapine treatment. Other glucose and lipid parameters were not altered significantly. CONCLUSIONS Although, the leptin level and body fat percentage were significantly increased, the concentration of circulating ghrelin was also significantly increased. Olanzapine may directly act on the secretion of ghrelin and induce appetite, resulting in weight gain.

Expression of insulin-like growth factor binding protein-3 (IGFBP-3) in human keratinocytes is regulated by EGF and TGF?1

Insulin‐like growth factor‐I (IGF‐I) is essential for normal epidermal homeostasis; however, the role of IGF binding proteins (IGFBPs), regulators of IGF action, remains unclear. Here we examine the regulation of human keratinocyte‐produced IGFBPs by epidermal growth factor (EGF), transforming growth factor beta 1 (TGFβ1), and IGF‐I, growth factors known to be active in skin. In the absence of added growth factors, IGFBP‐3 was the major binding protein secreted into the medium by primary keratinocytes. Addition of EGF or TGFβ1 to keratinocyte cultures resulted in a significant decrease in IGFBP‐3 abundance in conditioned medium when compared with control, untreated cells. Specifically, EGF (50 ng/ml) and TGFβ1 (50 ng/ml) reduced IGFBP‐3 abundance to 15 ± 6% and 22 ± 9%, respectively. Using Northern blot analysis, we found EGF and TGFβ1 (50 ng/ml) to reduce IGFBP‐3 mRNA levels in keratinocytes to 51 ± 12% and 50 ± 38%, respectively, when compared with control, untreated cells. Treatment with IGF‐I or its analogue des(1‐3)IGF‐I did not lead to any consistent change in IGFBP‐3 abundance. However, both IGF‐I and des(1‐3)IGF‐I at 100 ng/ml led to a modest increase in IGFBP‐3 mRNA levels in keratinocytes, suggesting posttranscriptional regulation of IGFBP‐3 abundance. We propose that local modulation of IGFBP‐3 abundance may represent another level of regulation of growth factor action in the epidermis, where EGF and TGFβ1 and possibly other local growth factors specifically regulate the availability of IGF‐I to its keratinocyte receptors. J. Cell. Physiol. 179:201–207, 1999.

Glucose and lipid metabolism of long-term risperidone monotherapy in patients with schizophrenia

Abstract  Risperidone has a relatively low risk of causing obesity and diabetes mellitus and is a first‐line treatment for schizophrenia. The aim of the present study was to investigate glucose and lipid metabolism, and feeding‐control parameters in schizophrenia patients treated with long‐term risperidone monotherapy. Fifteen patients with paranoid‐type schizophrenia who had been treated with risperidone and had Global Assessment of Function (GAF) scores >70 were selected and compared with healthy volunteers (n = 25). Single assessments of psychotic symptoms, side‐effects, Drug‐Induced Extrapyramidal Symptoms Scale (DIEPSS) score, bodyweight, body fat percentage and blood sampling were performed. Fasting blood glucose, insulin, hemoglobin A1c, homeostasis model assessment insulin resistance index (HOMA‐IR), total cholesterol, triglyceride, high density lipoprotein (HDL)‐, low density lipoprotein‐cholesterol, adiponectin, prolactin and feeding‐control parameters (ghrelin and leptin) were analyzed. The body fat percentage (P = 0.0018), body mass index (BMI) (P = 0.0150), fasting blood glucose (P = 0.0358), triglyceride (P = 0.0377), leptin (P = 0.0243), total ghrelin (P = 0.0067), active ghrelin (P = 0.0241) and prolactin (P < 0.0001) levels of patients treated with risperidone were significantly higher than those of healthy volunteers, while the HDL‐cholesterol level (P = 0.0222) was significantly lower. Although the patients had very mild psychiatric symptoms and maintained functionally high levels, the glucose and lipid parameters were significantly impaired compared to healthy volunteers. A high level of plasma ghrelin might increase appetite, leading to exacerbation of metabolic impairment.

Acute administration of clozapine concurrently increases blood glucose and circulating plasma ghrelin levels in rats.

OBJECTIVE Among antipsychotics, clozapine ranks highest in terms of the risk for weight gain and developing diabetes. However, the mechanism by which clozapine induces weight gain and diabetes remains unclear. The aim of this study was to determine the mechanism of clozapine-induced weight gain and hyperglycemia, and to clarify whether clozapine-induced hyperglycemia results from impairment of the system regulating appetite. METHODS Circulatory glucose, insulin, leptin and ghrelin levels were analyzed after acute administration of clozapine in rats. Clozapine (10 mg/kg) or a vehicle was injected intraperitoneally and blood samples were collected at 0, 15, 30, and 60 min after the injection. Clozapine (5, 10 or 20 mg/kg) or the vehicle was given, and blood samples were collected at 30 min after the injection. Since clozapine has receptor affinity for multiple neurotransmitters, selective antagonists of it, including dopamine, serotonin, alpha-adrenergic, muscarine and histamine were administered to clarify the pathway of clozapine-induced blood glucose and changes in plasma ghrelin. RESULTS Clozapine administration increased the blood glucose level at all time points (p<0.05) compared to controls. Plasma ghrelin was elevated at 30 min (p=0.0124) and 60 min (p=0.00152). Blood glucose was increased in rats given 5 (p=0.0344), 10 (p<0.0001), or 20 mg/kg (p<0.0001) clozapine, while plasma ghrelin was increased in rats treated with 10 mg/kg (p=0.0009) or 20 mg/kg (p=0.0059) clozapine. Blood glucose was increased in rats treated with a selective alpha1-adrenergic receptor antagonist (p<0.0001), while plasma ghrelin was significantly increased in rats given a selective alpha1- (p=0.025) or alpha2-adrenergic receptor antagonist (p=0.0003). CONCLUSIONS Clozapine impairs glucose metabolism and the appetite-regulation system. Clozapine increases blood glucose independent of insulin. The antagonistic action of alpha-adrenergic receptors is one of the mechanisms that induces both hyperglycemia and elevation of ghrelin.

Novel missense mutation (Leu466Arg) of the DAX1 gene in a patient with X-linked congenital adrenal hypoplasia.

We identified a DAX1 missense mutation, a substitution of arginine for leucine at codon 466 (Leu466Arg), in an infant with X-linked congenital adrenal hypoplasia (AHC). A heterozygous substitution, Leu466Arg, was also identified in his mother and sister. Since leucine at position 466 is well conserved among other orphan nuclear hormone receptor superfamilies and Leu466Arg was not detected among 50 normal Japanese control individuals, the mutation is most likely responsible for X-linked AHC. It is interesting to note that Leu466Arg among all mutations ever reported is located at the most C-terminal region of the DAX-1 protein. Most mutations identified previously were located in the C-terminal presumptive ligand binding domain. Hence, the C-terminal end of the DAX-1 protein may play an important role in the biological function, such as in normal adrenal embryogenesis.

Three Novel PHEX Gene Mutations in Japanese Patients with X-Linked Hypophosphatemic Rickets

X-linked hypophosphatemic rickets (XLH) is an X-linked dominant disorder characterized by renal phosphate wasting, abnormal vitamin D metabolism, and defects of bone mineralization. The phosphate-regulating gene on the X-chromosome (PHEX) that is defective in XLH has been cloned, and its location identified at Xp22.1. It has been recognized to be homologous to certain endopeptidases. So far, a variety of PHEX mutations have been identified mainly in European and North American patients with XLH. To analyze the molecular basis of four unrelated Japanese families with XLH, we determined the nucleotide sequence of the PHEX gene of affected members. We detected a new nonsense mutation (R198X) in exon 5, a new 3 nucleotides insertion mutation in exon 12 and a new missense mutation (L160R) in exon 5 as well as a previously reported nonsense mutation in exon 8 (R291X). These results suggest that:1) PHEX gene mutations are responsible for XLH in Japanese patients, and 2) PHEX gene mutations are heterogeneous in the Japanese population similarly to other ethnic populations.

No Genetic Mutation in Type II 3β-Hydroxysteroid Dehydrogenase Gene in Patients with Biochemical Evidence of Enzyme Deficiency

Nonclassic or the mild form of 3 beta-hydroxysteroid dehydrogenase (NC3 beta-HSD) deficiency is an entity which is identified with typical features of premature pubarche, hirsutism, or oligomenorrhea. In this study, type II 3 beta-HSD gene from 4 girls who were diagnosed as NC3 beta-HSD deficient, base on the adrenal steroidogenic responses to ACTH, was analyzed to determine whether NC3 beta-HSD deficiency was an allelic variant of classical 3 beta-HSD deficiency by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). We could not detect any alterations of type II 3 beta-HSD gene from these patients. Our result strongly suggests that unlike classical 3 beta-HSD deficiency, NC3 beta-HSD deficiency may be secondary adrenal biosynthetic defects, rather than dual inherited deficiencies.

Near-normal linear growth in the setting of markedly reduced growth hormone and IGF-1. A case report.

A 14.2-year-old prepubertal boy diagnosed with complete-type growth hormone deficiency and tertiary hypothyroidism, keeps growing in the height range between –1 and –2 SD. He has been treated with levothyroxine only. To understand the growth mechanism of this boy, we analyzed the serum growth hormone (GH) with a radioimmunoassay (RIA), serum GH bioactivity with Nb2 and erythroid progenitor cell bioassays, and growth hormone-binding protein (GHBP) with a ligand-mediated immunofunctional assay (LIFA). In addition, IGF-1 and free IGF-1 were analyzed by immunoradiometric assay (IRMA) and insulin-like growth factor-binding protein-3 (IGFBP-3) by Western immunoblot. Peak GH-RIA responses to insulin, arginine and GH-releasing factor, and nocturnal GH secretion, were low (0.5–2.3 ng/ml); bioactive GH was low (0.313 ng/ml), and GHBP was elevated (84 ng/ml). The serum levels of IGF-1 and free IGF-1 were continuously low, 17.1–39.3 and 0.17–0.26 ng/ml, respectively. Moreover, serum IGFBP-3 levels were low (1.68– 1.39 mg/l) and IGFBP-3 protease activity was negative. Prolactin and insulin were in the normal range. The result of the assay for growth-promoting activity showed that the patient’s serum stimulated normal erythroid progenitor cells twice as potently as did healthy thin adult control serum. These results suggest that GH and IGF-1 are not indispensable for maintaining physical growth in this boy. Thus, it appears that circulating GH and IGF-1 are not mandatory requirements for maintaining normal physical growth, and other, as yet uncharacterized, pathways or growth factors might be sufficiently compensatory under certain conditions.