Akio Nagasaka

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.

Quantitative modulation of thyroid iodide peroxidase by thyroid stimulating hormone

Abstract The activity of rat thyroid iodide peroxidase fell to 8% of the normal value 48 hours after hypophysectomy. Rats given injections of thyroid stimulating hormone manifested an enzyme activity indistinguishable from that of the sham-operated animals. Cycloheximide prevented the thyroid stimulating hormone-induced restoration of the enzyme activity. The incorporation of 14 C-leucine into the thyroid gland decreased gradually and reached two thirds of the sham-operated group by 48 hours after hypophysectomy. Thyroid stimulating hormone administration prevented this decrease, as observed for iodide peroxidase activity. Thyroidal RNA contents decreased also in hypophysectomized rats, thyroid stimulating hormone treatment prevented the reduction of RNA contents and no significant change was observed in thyroidal DNA contents. These data are consistent with the idea that protein biosynthesis is involved in thyroid stimulating hormone regulation of thyroidal iodide peroxidase and that the life span of the peroxidase is less than 48 hours.

Reduction of activity, but no decrease in concentration, of erythrocyte Cu, Zn-superoxide dismutase by hyperglycaemia in diabetic patients

Cu,Zn‐superoxide dismutase (SOD) activity in erythrocytes is affected by various diseases, including diabetes mellitus (DM). We investigated changes in the Cu,Zn‐SOD activity compared to changes in the Cu,Zn‐SOD concentration in erythrocytes obtained from patients with Type 2 (non‐insulin‐dependent) diabetes mellitus. Cu,Zn‐SOD activity in erythrocytes was significantly lower in Type 2 DM patients than in healthy non‐diabetic subjects. The activity correlated negatively with HbA1c, but not with other indicators of metabolic control, such as fasting blood glucose or plasma cholesterol or triglyceride. However, there was no statistically significant difference in erythrocyte concentration of Cu,Zn‐SOD between diabetic and control samples. Concentration did not correlate with enzymatic activity or HbA1c. These findings indicate that the inactivation of Cu,Zn‐SOD activity in erythrocytes of Type 2 DM patients by hyperglycaemia may be slow, because there is a negative correlation between the enzyme activities and HbA1c levels, but not fasting blood glucose levels. This is consistent with glycosylation of the active site of Cu,Zn‐SOD, without any effect of hyperglycaemia on the concentration of Cu,Zn‐SOD.

Effects of thyroid hormone on the sorbitol pathway in streptozotocin-induced diabetic rats

Sorbitol accumulation plays an important role in diabetic complications involving the kidney, nerves, retina, lens and cardiac muscle. To investigate the influence of thyroid hormone on the sorbitol pathway, we studied the effects of thyroid hormone on polyol metabolism in normal and diabetic rats. Rats were divided into three groups: controls, streptozotocin (STZ)-induced diabetic euthyroid rats (DM) and STZ-induced diabetic hyperthyroid (thyroxine-injected) rats (DM+HT). The sorbitol (Sor) concentrations in the kidney, liver and sciatic nerve (2.53+/-0.74, 0.97+/-0.16 and 24.0+/-5.1 nmol/mg protein, respectively) of the DM rats were significantly higher than those (1.48+/-0.31, 0.58+/-0.13 and 3. 1+/-0.6 nmol/mg protein) of the control rats. The Sor concentrations in the kidney and sciatic nerve of the DM+HT rats (1.26+/-0.29 and 9. 40+/-1.2 nmol/mg protein) were significantly lower than those in the DM rats. These values were reduced in the liver, unchanged in the kidney, and increased in the sciatic nerve from the hyperthyroid rats without diabetes. Thyroid hormone reduced the aldose reductase (AR) activities in the kidney, liver and sciatic nerve of the DM rats, and similarly reduced AR in the kidney and liver, but not in the sciatic nerve, of the non-diabetic rats. The sorbitol dehydrogenase (SDH) activities were decreased by thyroid hormone in the kidney and liver but not the sciatic nerve of DM rats. In the non-diabetic rats, this enzyme activity was decreased in liver, but not in kidney or sciatic nerve. A positive correlation between the Sor concentration and AR activity was observed in the kidney and liver but not in the sciatic nerve from control, DM and DM+HT rats. A negative correlation was observed between the Sor concentration and SDH activities in the same organs. These data suggest that thyroid hormone affects the sorbitol pathway, but the detailed mechanism whereby this hormone reduces the sorbitol content (especially in diabetic rats) remains to be clarified.

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.

Surface expression and release of soluble forms of CD8 and CD23 in CD40- and IL-4-activated mononuclear cells from patients with Graves' disease (GD).

We investigated the effect of T cell‐dependent B cell activation on the surface expression and release of the soluble forms of CD8 and CD23 by peripheral blood mononuclear cells (PBMC) obtained from patients with GD, versus patients with Hashimotos thyroiditis, and normal controls. Incubating the PBMC with anti‐CD40 MoAbs and IL‐4 increased the soluble CD23 levels in cells from all three groups. An increase in the number of CD23+ cells was observed in the PBMC from the patients with GD, but not in PBMC from Hashimotos thyroiditis or controls. Less soluble CD8 was released from anti‐CD40 antibody and IL‐4‐stimulated PBMC obtained from patients with GD relative to those from the controls. In addition, the number of CD8+ cells was significantly reduced in stimulated PBMC from the GD patients relative to those from controls. Incubation of PBMC with anti‐CD40 antibody plus IL‐4 did not affect the proportions of CD4+, CD20+, Fas+CD4+, and Fas+CD8+ cells. The addition of T3 to cultured PBMC from controls did not reproduce the changes in CD23+ and CD8+ cells noted in the samples from GD patients. Thus, T cell‐dependent B cell activation, mediated by a CD40 pathway, may reduce the number of CD8+ cells, causing exacerbation of GD.

Tyrosine hydroxylase indicates cell differentiation of catecholamine biosynthesis in neuroendocrine tumors

The intracellular localization of tyrosine hydroxylase (TH), which is the rate limiting enzyme in catecholamine (CA) biosynthesis, and its activity in various adrenal and other neuroendocrine tumors was studied. TH was strongly localized in adrenal medulla, pheochromocytoma, and paraganglioma, but was scatteredly expressed in neuroblastoma. TH was not detected in adrenocortical tumors, ganglioneuroma, and other neuroendocrine tumors. Neuron specific enolase (NSE) was found in all neuroendocrine tumors, but Grimelius staining showed only the secreting granules of the tumor cells. TH activity was significantly high in pheochromocytoma and paraganglioma as compared with that in normal adrenal gland, whereas TH activity was low in a neuroblastoma and was undetectable in other tumors. These findings indicate that TH correlates well with the biosynthetic function of CA in the tumor cell and, thus, both the immunostaining of TH and the measurement of its activity in adreno-medullary and related tumors may provide some information about the process of cell differentiation in these tumors.