Acute effects of Amomum villosum Lour. fruit extract on postprandial glycemia and insulin secretion: A single-blind,placebo-controlled,crossover study in healthy subjects

BackgroundAmomum villosum Lour., (Zingiberaceae) an herbaceous plant in the ginger family, has been used to treat various diseases. In a single-blind, randomized, crossover study, we assessed the postprandial blood insulin and blood glucose responses in healthy subjects (n = 40) after the Amomum villosum water extract (AVE) (5 g/person) or a placebo (5 g/person) consumption.MethodsDuring each treatment course, the healthy subject consumed a regular late afternoon meal, followed by fasting for 12 h, and arrived at the clinical study center the next morning. Blood insulin and blood glucose levels were assessed at 0, 30, 60, 90, and 120 min after AVE consumption. Between each treatment, the subjects accomplished one week of a washout period.ResultsThe AVE intake demonstrated a significant (67.26%) decline in postprandial blood glucose AUC_{0–120 min} (incremental area under the curve from 0 to 120 min) versus the placebo (P = 0.011). Furthermore, AVE reduced postprandial blood insulin AUC_{0–120 min} by 59.95% compared to the placebo group (P < 0.003), supporting the blood glucose results.ConclusionThis study revealed that AVE consumption significantly reduced postprandial insulin and glucose levels in healthy individuals, due in part to inhibition of α-glucosidase, and glucose transport.     

l-Cysteine supplementation lowers blood glucose, glycated hemoglobin, CRP, MCP-1, and oxidative stress and inhibits NF-κB activation in the livers of Zucker diabetic rats

This study examined the hypothesis that l-cysteine supplementation can lower insulin resistance, glycemia, oxidative stress, and markers of vascular inflammation in type 2 diabetes using Zucker diabetic fatty (ZDF) rats as a model. Starting at the age of 6 weeks, ZDF rats were supplemented orally (daily gavage, 8 weeks) with saline placebo (D) or l-cysteine (LC; 1 mg/kg bw) and fed a high-calorie diet. Six-week-old rats without any supplementation were considered baseline (BL) rats. D rats showed elevated fasting blood glucose, glycated Hb, CRP, and MCP-1 compared with BL rats in which there was no onset of diabetes. LC supplementation significantly lowered blood levels of glucose (18%, p =  0.05), glycated Hb (8%, p =  0.02), CRP (23%, p =  0.02), MCP-1 (32%, p =  0.01), and insulin resistance (25%) compared with levels seen in saline-supplemented D rats. There was a decrease in plasma protein oxidation levels (p <  0.01); however, GSH levels were similar in LC and D groups. Although LC did not change blood hematocrit or levels of transaminases, it did lower alkaline phosphatase (29%, p =  0.01) levels in comparison to D. Western blotting analyses of liver showed increased activation of NF-κB and Akt (50% pNF-κB and 20% pAkt) in D compared with BL rats. LC supplementation inhibited these effects (17% pAkt, 18% pNF-κB). This is the first report showing that l-cysteine supplementation can lower glycemia and markers of vascular inflammation in diabetes apparently by preventing NF-κB activation in a diabetic animal model.     

Is adrenomedullin a causal agent in some cases of type 2 diabetes?

The study of two populations with a recent onset of type 2 diabetes showed that a subset of the patients had higher levels of adrenomedullin (AM) than the rest of the diabetics. In this subset, physiological elevations of AM might have triggered the disease in predisposed individuals. Diabetics showed higher levels of AM than healthy controls. In addition, glycemia was measured in diabetic rats after injection of saline, AM, or antiAM antibody. AM elevated glycemia, whereas the antibody reduced circulating glucose to normal. These results suggest that manipulation of AM levels could represent a new approach in the management of diabetes for the appropriate individuals.     

Endocrine disruption in crustaceans due to pollutants: a review

The main endocrine-regulated processes of crustaceans have been reviewed in relation to the effects of endocrine-disrupting compounds (EDCs). Molting has been shown to be inhibited by several organic pollutants, such as xenoestrogens and related compounds, as well as by some pesticides. Most of these disrupters are thought to interfere with ecdysone at target tissues, although only for a few has this action been demonstrated in vitro. The heavy metal cadmium appears to inhibit some ecdysone secretion. Juvenoid compounds have also been shown to inhibit molting, likely by interfering with the stimulatory effect of methyl farnesoate. A molt-promoting effect of emamectin benzoate, a pesticide, has also been reported. As for reproduction, a variety of organic compounds, including xenoestrogens, juvenoids and ecdysteroids, has produced abnormal development of male and female secondary sexual characters, as well as alteration of the sex ratio. Cadmium and copper have been shown to interfere with hormones that stimulate reproduction, such as methyl farnesoate, as well as with secretion of the gonad inhibiting hormone, therefore affecting, for example, ovarian growth. Several heavy metals were able to produce hyperglycemia in crustaceans during short times of exposure; while a hypoglycemic response was noted after longer exposures, due to inhibition of secretion of the crustacean hyperglycemic hormone. The ecological relevance of EDCs on crustaceans is discussed, mainly in relation to the identification of useful biomarkers and sentinel species. New experimental approaches are also proposed.     

Glucose injection into the yolk influences intermediary metabolism in adult Nile tilapia fed with high levels of carbohydrates

Nutritional programming is a concept proposed to be applied in the field of fish nutrition to improve the use of new diets in aquaculture. This study aimed to investigate for the first time the effects of a glucose injection into the yolk at the alevin stage on intermediary metabolism and growth in adult Nile tilapia (Oreochromis niloticus) at 32–37 weeks later in the life. The early stimulus was performed through direct microinjection of 2 M glucose into yolk sacs of Nile tilapia alevin. Subsequently, in adult tilapia, the long-term effects of glucose stimulus on growth performance, blood metabolites, chemical composition in the liver and muscle, expression of genes involved in glucose transport and metabolism (glycolysis and gluconeogenesis) and related pathways (amino acid catabolism and lipogenesis) were investigated. Our results showed that, even though early glucose injection had no effect on growth performance in adult fish, very few significant effects on glucose metabolism were observed. Furthermore, to evaluate the potential metabolic programming after a dietary challenge, a 2 × 2 factorial design with two early stimuli (0.85% NaCl or 2 M glucose) and two different dietary carbohydrate intakes (medium-carbohydrate diet, CHO-M; high-carbohydrate diet, CHO-H) was performed between weeks 33 and 37. As expected, compared with the CHO-M diet, the CHO-H diet led to decreased growth performance, higher glyceamia and triglyceridemia, higher glycogen and lipid levels in the liver as well as down-regulation of gluconeogenesis and amino acid catabolism gene expressions. More interestingly, although early glucose injection had no significant effect on growth performance, it enhanced the capacities for lipogenesis, glycolysis and gluconeogenesis, particularly in fish that were fed the CHO-H diet. Thus, the nutritional programming of tilapia linked to glucose injection into the yolk of alevins is always visible at the adult stage albeit less intense than what we previously observed in juvenile.     

Chronic taurine supplementation ameliorates oxidative stress and Na+ K+ ATPase impairment in the retina of diabetic rats

Summary.  This study evaluates the effect of 4 months supplementation with 2% and 5% taurine (w/w) on the retina of diabetic rats. In non-diabetic rats, taurine does not modify glycemia, body weight, retinal conjugated dienes (CD), lipid hydroperoxide (LP), and Na⁺K⁺ATPase activity. In diabetic rat, at 2, 4, 8, 16 weeks following the onset of diabetes, retinal CD and LP are significantly and progressively increased, while pump activity is gradually and significantly reduced. In taurine supplemented diabetic rats, glycemia is not affected but lipid peroxidation is significantly decreased. Finally, taurine preserves ATPase activity being 5% more effective than 2% taurine. We conclude that taurine supplementation ameliorates biochemical retinal abnormalities caused by diabetes, thereby suggesting that taurine may have a role in the prevention of retinal changes in diabetes. Received November 26, 2001 Accepted January 10, 2002 Published online October 3, 2002 Authors' address: Prof. Flavia Franconi, Department of Pharmacology, University of Sassari, Via Muroni 23a, I-07100 Sassari, Italy, Fax: 39-79228715, E-mail: franconi@ssmain.uniss.it     

Central injections of noradrenaline and adrenaline differentially affect plasma free fatty acid and glucose in conscious pigeons (Columba livia)

The possible involvement of central noradrenergic and/or adrenergic circuits in central mechanisms controlling free fatty acids and glucose levels was investigated in conscious pigeons. The effects of intracerebroventricular injections of noradrenaline (80 nmol) or adrenaline (80 nmol) on plasma free fatty acids and glucose concentrations were examined. The possible role of the autonomic nervous system, of sympathetic terminals and of pituitary hormone release in the metabolic responses induced by intracerebroventricular injections of adrenaline and noradrenaline was investigated by systemic pretreatment with a ganglionic blocker (hexamethonium, 1 mg/100 g), guanethidine (5 mg/100 g), and somatostatin (15 μg/100 g), respectively, 15 min before intracerebroventricular administration of adrenaline, noradrenaline or vehicle. Intracerebroventricular noradrenaline injections strongly increased plasma free fatty acid concentration but evoked no change in blood glucose levels, while adrenaline treatment increased glycemia without affecting free fatty acid levels. Hexamethonium did not block the increase in plasma free fatty acids induced by noradrenaline, while somatostatin pretreatment abolished noradrenaline-induced lipolysis during the experimental period. Adrenaline-induced hyperglycemia was blocked by systemic injections of somatostatin, hexamethonium and guanethidine. The present results suggest that: (1) adrenergic and noradrenergic mechanisms may participate in central control of blood glucose and free fatty acids, respectively, as observed in mammals, (2) noradrenaline-induced lipolysis may be mediated by pituitary mechanisms, and (3) postganglionic sympathetic fibers, possibly innervating the endocrine pancreas, may be involved in adrenaline-induced hyperglycemia. Accepted: 14 April 2000     

Metabolic responses to glucoprivation induced by 2-deoxy-D-glucose in<Emphasis Type="Italic"> Brycon cephalus</Emphasis> (Teleostei,Characidae)

The effects of functional cytoglucopenia provoked by 2-deoxy-D-glucose (2-DG) were studied in adult Brycon cephalus, an omnivorous fish from the Amazon Basin in Brazil. Glycogen content in liver and muscle as well as plasmatic glucose, free fatty acids (FFA), insulin, and glucagon were measured. After 48 h fasting, an intraperitoneal saline injection (NaCl 0.6 g/100 ml) was administered to control fish, whereas the experimental group received 2-DG, dissolved in saline, in the dosage of 80 mg/kg (0.487 mmol/kg) or 150 mg/kg (0.914 mmol/kg) body weight; injection volume was 5 ml in all treatments. Blood and tissue samples were taken immediately before, and 2, 8, 10, and 24 h after administration of the drug or saline. Fish injected with both doses of 2-DG showed a marked increase in glycemia levels. Liver and muscle glycogen decreased after 2-DG administration and reached their lowest values 10–24 h after injection, while in control animals no significant changes were observed. Elevation in plasma glucagon was observed only in response to the maximum dosage of 2-DG administered, especially 10 h and 24 h post-injection. Plasma insulin levels were lower in animals treated with the glucose analogue but only statistically significant 24 h after drug administration. In conclusion, the administration of the non-metabolizable glucose analogue 2-DG in B. cephalus is a stimulus to generate responses towards an increase in the glucose available to tissues, which is a characteristic of a fasting situation. All the above data support the interest of 2-DG administration as a model to study carbohydrate metabolism adjustment mechanisms in fish.Abbreviations 2-DG 2-deoxy-D-glucose - FFA free fatty acids Communicated by G. Heldmaier     

Eimeria stiedae: weight, oocyst output, and hepatic function of rabbits with graded infections

Groups of 5 (38–40 days old) Eimeria stiedae-naive rabbits were infected with 0 (mock infection), 10², 10³, 10⁴, and 10⁵ sporulated oocysts of Eimeria stiedae (groups A, B, C, D, and E, respectively) and body weight, oocyst output, serum glutamic pyruvic and serum oxalacetic transaminases, bilirubinemia. lipemia, glycemia, and proteinemia were measured on diverse occasions for 50 days. Mortality and carcass and liver weights at the end of the experiment were also recorded. Mortality was 80% in group E, 40% in group D, and 0% in the other groups. Reduction of weight gain was observed from the 8th day of infection and actual loss from the 15th day in infected animals. On Day 50, the average body and carcass weights of all infected rabbits were 71.2 and 63.2%, respectively, of group A. Only groups D and E had absolute hepatomegaly and group C had relative liver enlargement. Patency and rate of increase of oocyst output were not related to dose but peak and declination of oocysts production were delayed in proportion to the infective dose.Serum glutamic pyruvic and glutamic oxalacetic transaminases were increased from Day 8 to Day 36, bilirubinemia and lipemia augmented from Day 22, and glycemia and total serum proteins decreased from Days 22 and 29, respectively. Bilirubinemia tended to recover sooner (toward Day 50) in rabbits with lighter infection and lipemia recovered from Day 36 in proportion to the size of the infective dose. Modifications of glycemia and total proteinemia were consistent but reached statistical significance only occasionally. The asexual reproduction of the parasites caused transient damage to the hepatocytes during the second week of infection, and later sexual stages altered the ductal epithelium from the fourth week.