Kentaro Fujiwara

Changes in Superoxide Dismutase Activities and Concentrations and Myeloperoxidase Activities in Leukocytes from Patients with Diabetes Mellitus

To investigate whether the two free-radical scavengers, Cu, Zn- and Mn-superoxide dismutase (SOD), are changed in leukocytes of diabetic patients, and the alteration of these enzymes correlates with the diabetic state, we measured the activity and concentration of these enzymes in leukocytes from diabetic patients. Both Cu, Zn-SOD and Mn-SOD activities in neutrophils and lymphocytes were significantly lower in patients with non-insulin-dependent diabetes mellitus than in healthy controls. The concentrations of these enzymes in leukocytes from diabetic patients, however, did not differ from those in controls. Cu, Zn-SOD and Mn-SOD activities in neutrophils inversely correlated with HbA(1c) concentrations. Myeloperoxidase activity in leukocytes was significantly reduced in NIDDM patients. These findings suggest that changes in these enzymes may affect the susceptibility to infection and immunocompetence of patients with diabetes.

Peripheral injection of risperidone, an atypical antipsychotic, alters the body weight gains of rats.

1. Risperidone is an atypical antipsychotic drug that possesses 5-hydroxytryptamine 5-HT2 receptor antagonism combined with milder dopamine D2 receptor antagonism. 2. Excessive bodyweight gain is one of the side-effects of antipsychotics. Risperidone treatment causes a greater increase in the body mass of patients than treatment with conventional antipsychotics, such as haloperidol. Therefore, the present study was undertaken in order to address the aetiology of the risperidone-induced bodyweight change in rats by examining the expression of leptin, an appetite-regulating hormone produced in white adipose tissue (WAT), and uncoupling protein (UCP)-1, a substance promoting energy expenditure in the brown adipose tissues (BAT). 3. Eight-week-old male rats were injected subcutaneously with risperidone (0.005, 0.05 or 0.5 mg/kg) twice daily for 21 days. Both bodyweight and food intake were monitored daily. On day 21, rats were decapitated and their serum leptin and prolactin concentrations were measured. Expression levels of leptin, Ucp1 and beta3-adrenoceptor (beta3-AR) genes in WAT and BAT were quantified using real-time polymerase chain reaction amplification. 4. Injection of 0.005 mg/kg risperidone into rats increased food intake and the rate of bodyweight gain, as well as the augmentation of leptin gene expression in WAT. Injection of 0.05 mg/kg risperidone increased food intake and leptin gene expression in WAT, but the rate of bodyweight gain was not affected. Injection of 0.5 mg/kg risperidone caused a reduction in bodyweight gain, as well as enhanced Ucp1 gene expression in BAT and serum prolactin concentrations. The serum leptin concentration and beta3-AR gene expression in WAT and BAT were not affected by injection of 0.5 mg/kg risperidone. 5. Although the changes in food intake observed in risperidone-injected rats were rationalized neither by serum leptin nor prolactin concentrations, the reduction in the rate of bodyweight gain following injection of 0.5 mg/kg can be explained, in part, by increased energy expenditure, as revealed by the remarkable increase in the UCP-1 mRNA expression level in BAT. The role of leptin in risperidone-induced alterations in bodyweight gain remain to be clarified.Ota et al . 1 recently addressed the important issue of developing an animal (rat) model of weight gain induced by novel ‘atypical’ antipsychotics Their study involved risperidone, which is known to induce weight gain in humans. 2 Most, but not all, novel antipsychotics induce weight gain, 3 although the weight gain induced by risperidone in humans is smaller in magnitude that that induced by olanzapine. 4 Olanzapine-induced weight gain has recently been modelled by us in rats 5 and it would be a considerable advantage for work in this area if risperidone-induced weight gain was also modelled effectively in rodents. Novel antipsychotic-induced weight gain has very serious clinical implications, being associated with enhanced morbidity and mortality, as well as reduced compliance. 6 However, the causes of the weight gain induced by many novel antipsychotics remain enigmatic. Many of the wide range of receptors at which novel antipsychotics act are implicated in the control of food intake (e.g. -adrenoceptors, various serotonergic and dopaminergic receptors and histamine H 1 receptors). However, it has, to date, proved impossible, on the basis of clinical studies, to determine the role of any one such receptor in antipsychotic-induced weight gain. 7 It is well documented that the weight gain induced by novel antipsychotics is associated with abnormalities in various hormonal systems, including leptin, 8 insulin 9 and prolactin. 7 Thus, it seems most likely that the development of animal models of novel antipsychotic-induced weight gain in which measures of food intake and bodyweight are supplemented by metabolic and endocrine measures, exactly as in the study by Ota et al ., 1 will prove a very powerful approach with which to advance this field. Indeed, in a recent major review of this area, Baptista et al . 7 highlighted the need to develop such models as a primary current ‘research perspective’. Thus, the type of empirical research reported by Ota et al . 1 is to be highly commended. It is, however, regrettable that examination of the work reported by Ota et al . 1 suggests that the conclusions they have drawn from their data relating to bodyweight and food intake are not supported by the statistical analysis presented and, thus, attempts to relate these findings to metabolic and endocrinological measures may be invalid. In their study, they administered risperidone for 21 days to four groups of rats treated with either vehicle or one of three doses of risperidone. Bodyweights and food intake were recorded daily. These data are reported as being analysed by repeated-measures

Scavenging effect of nicorandil on free radicals and lipid peroxide in streptozotocin-induced diabetic rats.

Free radicals and lipid peroxide (LPO), easily formed in the diabetic state, play an important role in the development of diabetic complications. Potentially, nicorandil may reduce the production of free radicals and LPO in various organs. In fact, increased LPO levels in the serum, kidney, and cardiac muscle of diabetic (DM) rats were reduced by nicorandil treatment (N treatment). Xanthine oxidase (XOD), which produces free radicals, was decreased in the liver and increased in the kidney of DM rats compared with control rats, and these changes were prevented by N treatment. The concentration of Cu, Zn-superoxide dismutase (SOD) decreased in the cardiac muscle and increased in the kidney of DM rats, and these changes returned to normal after N treatment. The decreased concentration of Mn-SOD in the liver, kidney, and cardiac muscle from DM rats was also reversed by N treatment. The changes in catalase and glutathione peroxidase (GSH-PX) activities in DM rats were not improved effectively by N treatment. Another K-adenosine triphosphate (K-ATP) channel opener, tilisolol hydrochloride, had an effect similar to that of nicorandil. The effects of nicorandil and tilisolol were studied only in DM rats. These data imply that N treatment, as an antioxidative therapy, may be beneficial in preventing diabetic complications due to lipoperoxidation and free radicals in DM rats.

The therapeutic effect of lipo PGE1 on diabetic neuropathy-changes in endothelin and various angiopathic factors.

A high blood concentration of endothelin (ET)-1 may participate in the onset and progress of diabetic microangiopathy, resulting in neuropathy. We examined the therapeutic effects of prostaglandin E1 (PGE1), which possesses both a peripheral vasodilating action and inhibition of platelet aggregation, on diabetic microangiopathy. Increases in both skin temperature and peripheral never conduction velocity in diabetic patients were recorded four weeks after Lipo PGE1 administration. A quantitative decrease in urinary albumin concentration was also observed, suggesting its efficacy of action was on diabetic nephropathy. Lipo PGE1 administration reduced the elevated circulating plasma ET-1 levels in the diabetic patients. As an increase in ET-1 concentrations is thought to correlate with the onset and progress of diabetic microangiopathy, the reduction of plasma ET-1 concentration by Lipo PGE1 administration may be one reason for the improvement in diabetic neuropathy and nephropathy.

Alteration of Endothelin-1 Concentration in STZ-Induced Diabetic Rat Nephropathy

Background: Recently, an endothelin (ET-1) with a potent vasoconstrictive activity and stimulative activity of vascular muscular cell growth was discovered and blood ET-1 levels were higher in diabetic patients than in healthy subjects, suggesting that high ET-1 levels assist development and progression of diabetic microangiography. Methods: We examined renal function, and serum and tissue ET-1 levels in streptozotocin (STZ)-induced diabetic rats treated with a prostaglandin (PG) I2 derivative to investigate the effect of PGI2 in diabetic vascular disturbance. Results: Renal weight, urinary albumin, urinary N-acetyl-β,D-glucosaminidase (NAG) and serum ET-1 levels increased in STZ-induced diabetic rats, and a tendency to increase in renal tissue ET-1 levels was observed. Furthermore, electron-microscopic findings in the kidneys showed mesangial cell proliferation and mesangial matrix expansion which might be caused by diabetic nephropathy. The PGI2 derivative reduced urinary albumin and NAG levels in STZ-induced rats. It was considered, therefore, that the PGI2 derivative is effective in diabetic nephropathy. As the PGI2 derivative also reduced renal tissue ET-1 levels, improvement of diabetic nephropathy partially was considered to result from the reduction of renal tissue ET-1 levels. Conclusion: In STZ-induced rats, increased serum ET-1 levels and a tendency to increase in renal tissue ET-1 levels were associated with increases in urinary albumin and NAG levels, and these levels were decreased by a PGI2 derivative. These findings suggested that increased ET-1 concentrations assist development and progression of diabetic nephropathy, especially diabetic microangiopathy, and the PGI2 derivative may be effective for inhibition of diabetic microangiopathy mediated by reduction of ET-1 concentrations.

The effects of CD40‐ and interleukin (IL‐4)‐activated CD23+ cells on the production of IL‐10 by mononuclear cells in Graves’ disease: the role of CD8+ cells

The possible roles of CD8+ cells in the abnormal T cell‐dependent B‐cell activation in Graves’ disease were investigated by analysing lymphocyte subsets in peripheral blood mononuclear cells (PBMC) and their production of soluble factors and cytokines such as IL‐10 in patients with Graves’ disease, Hashimoto’s thyroiditis and normal controls. The PBMC were separated into CD8+ and CD8‐depleted cells by magnetic separation columns, and cultured for 7 days with or without anti‐CD40 monoclonal antibodies and IL‐4. The culture supernatant was assayed for sCD23 and IL‐10 using EIA, and the remaining cells were analysed by flow cytometry. Stimulation with anti‐CD40 antibody together with IL‐4 increased sCD23 levels and the number of CD23+ cells. The latter was further augmented by depletion of CD8+ cells. This combination of B cell stimulants increased production of IL‐10 by PBMC from patients with Graves’ disease. The CD40‐ and IL‐4‐activated production of IL‐10 was decreased by CD8+ cell depletion. In contrast, constitutive production of IL‐10 was increased after CD8+ cell depletion in a group of patients with low basal secretion levels (<35 ng/ml). It was, however, decreased in a group with higher basal production levels, but such a relationship was not found in the normal control group. Thus, T cell‐dependent B‐cell activation via a CD40 pathway activates CD23+ cells, leading to over‐production of IL‐10 and a shift of the Th1/Th2 balance to Th2 dominance, while CD8+ cells may suppress this activation to counteract the Th2 deviation in Graves’ disease.

Effect of peripheral lipopolysaccharide injection on dopamine content in murine anterior olfactory nucleus.

Summary. Norepinephrine turnover rate in the murine locus coeruleus (LC) is known to be enhanced by the intraperitoneal (i.p.) injection of lipopolysaccharide (LPS). Approximately 40% of LC neurons are also known to project to the olfactory bulb (OB) and the anterior olfactory nucleus (AON). Therefore, we investigated whether an i.p. injection of 500 μg LPS could modulate the catecholamine biosynthesis in these sites in 8-week-old C3H/HeN male mice. Unexpectedly, the content of norepinephrine was not elevated in both sites during 6-h-observation after LPS injection. The contents of dopamine and its metabolites in the AON were highly increased at 4 h after LPS injection, whereas those in the OB were not elevated during 6-h-observation. Although the AON has been considered not to belong to the dopaminergic neuron system, our report is the first to show an elevated dopamine content in the AON under a stressful condition such as endotoxemia.

Urinary sorbitol measurement and the effect of an aldose reductase inhibitor on its concentration in the diabetic state.

The amounts of sorbitol (SOR) excreted in 24-h urine were determined on two groups, i.e., diabetic and nondiabetic patients, using an improved method in which ion exchange resin column processing was applied, and these levels were compared with SOR levels in whole blood. Urinary SOR concentration was also determined in diabetic and normal rats in the same manner and its relationship to aldose reductase (AR) activity in whole blood was investigated. Changes in SOR levels in urine and whole blood were compared in diabetic rats after administration of an AR inhibitor (ARI). Whole blood SOR levels and urinary SOR excretion were significantly higher in diabetic patients than in nondiabetic patients. The same results were obtained in the animal models. In diabetic rats, the urinary SOR excretion was about five times higher than that in control rats, and the AR activity in whole blood was also significantly higher. The increase in urinary SOR excretion and whole blood SOR levels, as well as AR activity, in blood in the diabetic state was inhibited by ARI administration. The influence of the diabetic state and the efficacy of the ARI were more marked in urinary SOR excretion than in whole blood SOR levels. These data indicate that determinations of urinary SOR excretion and AR activity are easily measurable and of benefit to assessing the diabetic condition.

Exon 3 of tyrosine hydroxylase gene: lack of association with Japanese schizophrenic patients.

Tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine (DA) biosynthesis.1,2 Exon 3 of the human TH gene encodes the sequence from Ser31 to Glu104 of type 1 enzyme,3,4 which contains the critical parts for regulation of the catalytic activity. The amino acid residues Gly36-Arg37-Arg38 were identified as a key sequence for DA to exert its inhibitory effect on catalytic activity.5–7 Therefore, we screened the nucleotide sequences of exon 3 from 201 Japanese patients with schizophrenia to explain the elevation in the synaptic or presynaptic DA concentrations in the schizophrenic brain,8–11 based on the hypothesis that any mutation changing the amino acid sequence Gly36-Arg37-Arg38 would result in the elevation of DA synthesis, due to a reduced inhibitory effect of DA on the catalytic activity.5–7 However, no mutated sequences of exon 3 and both exon–intron boundaries were detected in any of the patients examined. Polymorphisms generating Val81 and Met81 were compared of the distributions of genotype and allele between the patients and 175 Japanese healthy controls, which did not suggest an association between the polymorphism and schizophrenia. These results indicate that exon 3 of the human TH gene lacks association with schizophrenia in Japanese patients.