Ken-Ichi Ohtani

Serum leptin concentration is associated with total body fat mass, but not abdominal fat distribution.

OBJECTIVE: The obese (ob) gene encodes leptin which inhibits appetite and stimulates thermogenesis. Serum leptin concentrations are determined by total body fat mass, but the influence of visceral fat accumulation and other metabolic factors have not been clinically determined. METHODS: We determined the correlations between serum leptin concentrations and the total body fat mass, abdominal fat mass, abdominal fat distribution (estimated by ultrasound), and circulating metabolic factors in 104 Japanese healthy subjects (11 men and 93 women). In addition, the effect of food restriction (30 kcal/kg desired body weight/day) for four weeks on serum leptin concentrations were also examined in 30 women. RESULTS: There was a significant correlation between serum leptin concentrations and total body fat mass (r=0.708, P<0.0001), the percentage of body fat (r=0.561, P<0.001), and the body mass index (BMI, r=0.630, P<0.001). Serum leptin concentrations were correlated with the abdominal wall preperitoneal and subcutaneous fat pad thickness, but not the abdominal wall fat index (AFI). Serum leptin concentrations were also correlated with serum immunoreactive insulin (IRI), but not glucose, or free fatty acid (FFA) concentrations. The weight loss after food restriction for four weeks significantly (P=0.016) reduced the serum leptin concentrations with a significant reduction of body fat mass, serum glucose, IRI and FFA concentrations. However, there was no significant correlation of the percentage change in serum leptin concentrations to that in body fat mass after food restriction. CONCLUSION: Serum leptin concentrations are well correlated with the total body fat mass in healthy subjects. Differences in abdominal fat distribution do not appear to be related to a difference in the in vivo leptin production from adipose tissue.

Estrogen increases hypothalamic neuropeptide Y (NPY) mRNA expression in ovariectomized obese rat

We determined the changes in neuropeptide Y (NPY) mRNA expression of the arcuate nucleus (ARC) in sham-operated (SHAM) and bilaterally ovariectomized (OVX) rats with estradiol (E2) supplement. Ovariectomy increases body weight gain for 3 weeks, accompanied by an increase of daily food intake. Ovariectomy significantly reduced serum corticosterone levels. E2 supplement reversed the effects of ovariectomy on body weight gain, food intake and serum corticosterone levels. Ovariectomy significantly increased NPY mRNA expression in the ARC. E2 supplement decreased NPY mRNA expression in the ARC of OVX rats. The present findings indicated that hypothalamic NPY mRNA expression, which involves the regulation of feeding behavior, are in parallel with circulating estrogen levels. Hypothalamic NPY mRNA expression may be important in the induction of hyperphagia after the withdrawal of estrogen by bilateral ovariectomy.

Long-term effect of eicosapentaenoic acid ethyl (EPA-E) on albuminuria of non-insulin dependent diabetic patients

Dietary cod-liver oil containing eicosapentaenoic acid is effective on microvascular albumin leakage in diabetic patients with albuminuria. We determined the long-term effects of oral pure eicosapentaenoic acid ethyl (EPA-E: 900 mg/day) administration on diabetic nephropathy in non-insulin dependent diabetic (NIDDM) patients. The effects of EPA-E were determined by observing the changes of the index of urine albumin excretion level/urine creatinine (Cr) excretion level (UAI), the ratio of beta 2-microglobulin excretion level/urine Cr excretion level (beta 2-MG/Cr) and the ratio of N-acetyl-D-glucosaminidase excretion level/urine Cr excretion level (NAG/Cr) at 3, 6 and 12 months after the start of the treatment. Oral EPA-E administration immediately improved the increased UAI at 3 months after the start of treatment. A significant improvement of the UAI by EPA-E was sustained 12 months later. EPA E administration also tended to decrease the urine beta 2-MG/Cr ratio from 6 months, but the difference was statistically not significant. However, the urine NAG/Cr ratio was not changed by EPA-E administration. EPA-E administration did not affect blood pressure levels, glycemic control and lipid metabolism in these patients. The present data indicated that EPA-E administration improved increased albumin excretion in NIDDM patients with nephropathy and its effects on albuminuria sustained for at least 12 months after the start of treatment. However, tubular factors were not influenced by EPA-E administration.

Pioglitazone increases circulating adiponectin levels and subsequently reduces TNF‐α levels in Type 2 diabetic patients: a randomized study

Background   Adipocytokines are involved in the development of insulin resistance and endothelial dysfunction in diabetic patients. However, the relationship between these factors remains unclear. We observed a chronological change in circulating adipocytokines and blood pressure levels with administration of oral hypoglycaemic agents in Type 2 diabetic (T2DM) subjects.

Troglitazone (CS-045) Inhibits β-Cell Proliferation Rate Following Stimulation of Insulin Secretion in HIT-T 15 Cells

Thiazolidinedione analogs are new antidiabetic agents that attenuate peripheral insulin resistance in noninsulin-dependent diabetic patients; however, the effects of these agents on insulin secretion are not known. We determined the short-term and long-term effects of troglitazone (CS-045) on insulin secretion in a Syrian hamster clonalβ -cell line, HIT-T 15 cells. The direct effect of troglitazone (CS-045: 10−6–10−4 m) on insulin secretion was examined in F-12 K incubation medium containing 7 mm glucose. CS-045 significantly stimulated insulin secretion within 10 min at the concentration of 10−4 m and dose dependently stimulated insulin secretion within 60 min at the concentration of 10−6–10−4 m. The addition of 10−5 m CS-045 showed an immediate increase of cytoplasmic free Ca2+ concentrations ([Ca2+]i). Removal of extracellular Ca2+ by the addition of 1.5 mm EGTA completely abolished the 10−4 m CS-045-induced insulin secretion for 10-min. Long-term incubation (24 h) with 10−4 m CS-045 significantly decr...

LEPTIN STIMULATES INSULIN SECRETION AND SYNTHESIS IN HIT-T 15 CELLS

Leptin, an ob gene product, corrects hyperinsulinemia in ob/ob mice. The leptin receptor may exist in pancreatic islets. The present studies were undertaken to determine the direct effect of 1-100 ng/ml recombinant leptin on insulin secretion and synthesis in HIT-T 15 cells by using static culture system. The addition of recombinant leptin significantly increased insulin secretion for 20 min at the highest concentration (100 ng/ml). The addition of recombinant leptin dose-dependently increased insulin secretion for 24 h in the 7 mM glucose-containing F-12 K medium. The incubation with recombinant leptin for 24 h increased preproinsulin mRNA expression, assessed with reverse transcription-polymerase chain reaction (RT-PCR) method. It was furthermore demonstrated that HIT-T 15 cells possessed the specific binding site for [125I]-labeled leptin. The present study demonstrated the existence of the leptin-specific binding sites that mediate its stimulatory effect on insulin secretion and synthesis in HIT-T 15 cells.

Orchiectomy and response to testosterone in the development of obesity in young Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats.

OBJECTIVE: Withdrawal of testosterone prevents the development of hyperglycaemia in male Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats, a model of non-insulin-dependent diabetes mellitus (NIDDM), but the exact mechanism has not been established. The present studies were undertaken to examine a possible role of testosterone in the development of obesity in young OLETF rats who have not shown marked hyperphagia.METHODS: Body weight, food intake and circulating concentrations of metabolic factors including immunoreactive leptin (IRL) were measured at five weeks of age in young male OLETF rats and their lean controls, Long-Evans-Tokushima-Otsuka (LETO) rats. At six weeks of age, both LETO and OLETF rats were bilaterally orchiectomized (Orchx) and half of each group implanted with a silastic tube containing testosterone. After a three week observation period, all animals were killed and circulating concentrations of metabolic factors and the ob gene expression in retroperitoneal white adipose tissues were measured.RESULTS: Body weight and 24 h food intake were already increased in OLETF rats at five weeks of age. Serum testosterone concentrations were significantly lower in OLETF rats than in LETO rats. Expression of the ob gene was significantly decreased in the retroperitoneal white adipose tissue of OLETF rats, and their serum IRL concentrations were lower. Food intake and body weight gain for three weeks after the operation were significantly lower in the Orchx group of OLETF rats than in the sham-operated group. Hyperglycaemia, accompanied by hyperinsulinaemia, was attenuated by orchiectomy in OLETF rats. Circulating IRL concentrations were significantly higher in OLETF rats than in LETO rats and decreased by orchiectomy. Testosterone supplement reversed all of the changes caused by orchiectomy in OLETF rats. In contrast, the changes, which were observed after orchiectomy in OLETF rats, were not obvious in LETO rats.CONCLUSION: The present data indicate that testosterone plays a role in the development of obesity and NIDDM in young OLETF rats, but that changes of leptin production in white adipose tissue may not be important in the development of obesity in young OLETF rats.

Epalrestat, an Aldose Reductase Inhibitor, Improves an Impaired Generation of Oxygen-Derived Free Radicals by Neutrophils From Poorly Controlled NIDDM Patients

OBJECTIVE To study the in vivo effect of epalrestat (Epa), an aldose reductase inhibitor, on the generation of oxygen-derived free radicals by neutrophils from poorly controlled NIDDM patients (HbA1c > 10%). RESEARCH DESIGN AND METHODS A total of 31 diabetic patients were randomly divided into two groups: an Epa(+) group of 16 patients treated with 150 mg/day epalrestat and an Epa(−) group of 15 patients treated without epalrestat. A control group of 20 age- and sex-matched normal healthy subjects also participated. HbA1c, postprandial plasma glucose (PPG), and neutrophil bactericidal function were measured before and at the end of the drug treatment period (4 weeks). Neutrophil bactericidal function was measured as chemilu-minescence amplified by a Cypridina luciferin analog (CLA), which is dependent on O2− generation, and by luminol (L), which is highly dependent on OCl− generation, in response to formyl-methonyl-leucyl-phenylalanine (fMLP). RESULTS At the start of the experiment, both CLA-dependent chemiluminescence (CLA-DCL) and L-dependent chemiluminescence (L-DCL) were clearly decreased in diabetic subjects (64 and 54%, respectively; P < 0.05) compared with control subjects (2,182 ± 144 and 3,221 ± 173 kc · min−1 · 10−6 cells, respectively). At the end of the experiment, CLA-DCL and L-DCL in the Epa(+) group were significantly improved by 44 and 46%, respectively; however, these values were still lower than the corresponding results in the control group. HbA1c and PPG in both the Epa(+) and Epa (−) groups were significantly higher than in the control group, and treatment had no effect on either HbA1c or PPG. CONCLUSIONS These data suggest that epalrestat may be a useful drug to prevent infection by improving the impaired O2− and OCl− generation by neutrophils from poorly controlled NIDDM patients.

Effect of Eicosapentaenoic Acid Ethyl en Urine Albumin Excretion in NIDDM

presence of laterality in retinopathy was defined when > 2 grades difference were found between eyes in a patient. Fluorescent angiography was made in some cases to determine whether retinopathy was preproliferative or proliferative. A total of 15 patients developed brain infarction during the follow-up period. As shown in Table 1, the percentage of brain infarction in patients with asymmetric retinopathy was 41.7% (5 of 12), which was significantly higher than 7.7% in patients with symmetric retinopathy or 7.7% in patients without retinopathy. The laterality of brain infarction determined by CATscan coincided with that of the worse side of asymmetrical retinopathy in 4 of 5 patients. No differences were observed in sex, age, duration of diabetes, BP, BM1, fasting blood glucose, HbA: or serum lipid levels among the 3 groups in 1981. In some cases, asymmetry of retinopathy disappeared during the follow-up period. The asymmetry of retinopathy significantly persisted in 42% of patients who had asymmetry at the starting point and throughout the follow-up period. This contrasted with the 4% of patients who had a new appearance of asymmetry in symmetric retinopathy (P < 0.001). By the multiple regression analysis for the incidence of brain infarction in 77 patients with retinopathy, male sex and fundoscopic laterality indicated a significantly high risk for brain infarction (t values are 1.76 and 2.24, respectively). However, age, sBP, and HbAx were not associated with the incidence of brain infarction. The laterality of retinopathy in our cases was observed significantly more repetitively compared with symmetric retinopathy patients. Therefore, some extraocular factors such as arteriosclerosis or anomaly of carotid-brain vasculature may persist in diabetic patients with asymmetric retinopathy and may accelerate the diabetic retinopathy. This acceleration may be uneven in each side of the eyes, because in our cases the site of brain infarction coincided with that of retinopathy. We conclude that laterality of diabetic retinopathy is one of the predictors for brain infarction development in patients with diabetes mellitus.

Acarbose partially prevents the development of diabetes mellitus by multiple low-dose streptozotocin administration

Prophylactic insulin treatment prevents the development of hyperglycemia in animal models of insulin-dependent diabetes mellitus. Acarbose is a new antidiabetic drug which improves hyperglycemia by inhibiting alpha-glucosidase. In the present study, we determined the preventive effect of acarbose against multiple low-dose streptozotocin (MLDSTZ)-induced diabetes mellitus. The male ICR mice were fed acarbose (40 mg/100 g) containing powdered chow before the start of STZ administration. The mice were sacrificed at 3 and 10 days after the final STZ injection. MLDSTZ decreased serum immunoreactive insulin (IRI) levels and increased plasma glucose levels. Acarbose administration tended to decrease plasma glucose and serum IRI levels were significantly reduced in vehicle-treated mice. Acarbose administration significantly attenuated the degree of inflammation and destruction in pancreatic islets after MLDSTZ administration. In conclusion, acarbose-induced attenuation of acute hyperglycemia following MLDSTZ partially prevents the severity of pancreatic islet damage.