Multiple molecular targets underlie the antidiabetic effect of Nigella sativa seed extract in skeletal muscle, adipocyte and liver cells.

AIM: Nigella sativa (N. sativa) is a plant widely used in traditional medicine of North African countries. During the last decade, several studies have shown that extracts from the seeds of N. sativa have antidiabetic effects. METHODS: Our group has recently demonstrated that N. sativa seed ethanol extract (NSE) induces an important insulin-like stimulation of glucose uptake in C2C12 skeletal muscle cells and 3T3-L1 adipocytes following an 18 h treatment. The purpose of the present study was to elucidate the pathways mediating this insulin-like effect and the mechanisms through which these pathways are activated. RESULTS: Results from western immunoblot experiments indicate that in C2C12 cells as well as in H4IIE hepatocytes, but not in 3T3-L1 cells, NSE increases activity of Akt, a key mediator of the effects of insulin, and activity of AMP-activated protein kinase (AMPK), a master metabolic regulating enzyme. To test whether the activation of AMPK resulted from a disruption of mitochondrial function, the effects of NSE on oxygen consumption were assessed in isolated liver mitochondria. NSE was found to exhibit potent uncoupling activity. CONCLUSION: Finally, to provide an explanation for the effects of NSE in adipocytes, PPARgamma stimulating activity was tested using a reporter gene assay. Results indicate that NSE behaves as an agonist of PPARgamma. The data supports the ethnobotanical use of N. sativa seed oil as a treatment for diabetes, and suggests potential uses of this product, or compounds derived thereof, against obesity and the metabolic syndrome.

Antiobesity and antidiabetic effects of biotransformed blueberry juice in KKA(y) mice.

AIM: Biotransformation of blueberry juice by the Serratia vaccinii bacterium gave rise to adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and glucose uptake in muscle cells and adipocytes, but inhibited adipogenesis. This study investigated the antiobesity and antidiabetic potential of biotransformed blueberry juice (BJ) in KKA(y) mice, rodent model of leptin resistance. METHODS: BJ was incorporated in drinking water of KKA(y) mice. Parameters of body weight, food intake, plasma glucose, insulin, leptin, and adiponectin were measured. Before and after therapy, animals were subjected to an oral glucose tolerance test. At the end of treatment, liver, muscle, kidney, epididymal fat pad, abdominal fat pad, and dorsal fat pad were collected and weighed. RESULTS: Incorporating BJ in drinking water protected young KKA(y) mice from hyperphagia and significantly reduced their weight gain. Moreover, BJ protected young KKA(y) mice against the development of glucose intolerance and diabetes mellitus. Chronic BJ administration in obese and diabetic KKA(y) mice reduced food intake and body weight. This effect could not fully explain the associated antidiabetic effect because BJ-treated mice still showed lower blood glucose level when compared with pair-fed controls. The adipokines pathway also seems to be involved because BJ significantly increased adiponectin levels in obese mice. CONCLUSIONS: This study shows that BJ decreases hyperglycemia in diabetic mice, at least in part by reversing adiponectin levels. BJ also protects young pre-diabetic mice from developing obesity and diabetes. Thus, BJ may represent a novel complementary therapy and a source of novel therapeutic agents against diabetes mellitus.

Antioxidant and mitochondrial protective effects of silibinin in cold preservation-warm reperfusion liver injury.

AIM OF THE STUDY: Silybum marianum (milk thistle) is a Mediterranean plant that has been used since Greco-Roman times to treat liver ailments. Silibinin, the most active hepatoprotective constituent of the plant's seed, possesses antioxidant and anti-inflammatory properties. We thus assessed its protective potential in liver transplantation injury. MATERIALS AND METHODS: Rat livers were isolated and preserved during 24h at 4 degrees C in University of Wisconsin (UW) solution alone (control), UW containing 100 microM silibinin or UW containing vehicle (ethanol). Livers were then reperfused at 37 degrees C for 1h with Krebs-Henseleit solution supplemented with 20% erythrocytes. RESULTS: Compared to control, cold preservation and warm reperfusion promoted lipid peroxidation (+40%) and superoxide anion generation (+147%), while attenuating reduced glutathione (-23%), mitochondrial ATP content (-57%) and respiratory control ratio (RCR; -37%). Preservation done in presence of silibinin improved parameters affected by preservation and reperfusion. In fact, silibinin promoted an increase of ATP and RCR by, respectively, 39 and 16% and decreased oxidative stress to values observed in livers never preserved nor perfused. CONCLUSIONS: In conclusion, silibinin shows promise in protecting the liver from cold preservation/warm reperfusion damages. Moreover our study suggests that concepts of traditional medicine have the potential to be transposed successfully in the context of modern medical interventions such as liver transplantation surgery.

Maternal anthropometric risk factors for caesarean delivery before or after onset of labour.

OBJECTIVE: To quantify the effects of pre-pregnancy body mass and gestational weight gain, above and beyond their known effects on birthweight, on the risk of primary and repeat caesarean delivery performed before or after the onset of labour. DESIGN: Hospital-based historical cohort study. SETTING: Canadian university-affiliated hospital. POPULATION: A total of 63 390 singleton term (> or = 37 weeks gestation) infants with cephalic presentation. METHODS: We studied prospectively archived deliveries at the Royal Victoria Hospital in Montreal, Canada, from 1 January 1978 to 31 March 2001 using multiple logistic regression models to estimate relative odds of caesarean delivery. MAIN OUTCOME MEASURE: Caesarean delivery, primary or repeat and before or after the onset of labour. RESULTS: Pregravid obesity (body mass index > or = 30 kg/m2) increased the likelihood of primary caesarean delivery before (OR = 2.01, 95% CI 1.39-2.90) and after (OR = 2.12, 95% CI 1.86-2.42) the onset of labour. High net rate of gestational weight gain (> 0.50 kg/week) increased the risk but only after labour onset (OR = 1.40, 95% CI 1.23-1.60). Among women with a previous caesarean, high weight gain modestly increased risk but only before labour (OR = 1.38, 95% CI 1.04-1.83), whereas obesity increased the risk of caesarean delivery both before (OR = 1.85, 95% CI 1.44-2.37) and after (OR = 1.96, 95% CI 1.11-3.47) labour onset. Increased risks of macrosomia accounted for the association between pregravid adiposity and repeat caesarean delivery performed after but not before the onset of labour. CONCLUSIONS: Pregravid obesity increases the risk of caesarean delivery both before and after the onset of labour and both with and without a history of caesarean.

Outcome of neonates less than 30 weeks gestation with histologic chorioamnionitis.

The purpose of this study was to determine the short-term outcome of newborns less than 30 weeks gestation when there is definite placental histologic chorioamnionitis. A retrospective analysis was performed of records of all neonates delivered at our institution from January 1989 through January 1999. This information was retrieved from our perinatal database and pathology database. The population was stratified according to the presence or absence of histologic chorioamnionitis. Statistical analysis was performed using student t-test and Mann-Whitney method. Logistic regression was used to control for potential confounding variables. There were 392 neonates less than 30 weeks gestation delivered during this time period. Complete placental histology was available for 342 patients (87.4%). Histologic chorioamnionitis was identified in 140 (40.9%) cases. Those with histologic chorioamnionitis delivered sooner (26.3 versus 27.5 weeks), were of lower birth weight (920.1 versus 1029.8 g), and had lower 5-minute Apgarscores. Neonatal septicaemia and pneumonia were strongly associated with underlying histologic chorioamnionitis. There was a significant reduction in the incidence of respiratory distress syndrome (RDS) when histologic chorioamnionitis was present. Severe histologic chorioamnionitis increases the risk of premature delivery and is strongly associated with neonatal sepsis. There is a significant reduction in the incidence of RDS and neonatal mortality.

Insulin induces cation fluxes and increases intracellular calcium in the HTC rat hepatoma cell line.

BACKGROUND/AIMS: Rat hepatoma HTC cells were used to study conductive pathways implicated in insulin-induced cation and calcium influx into liver cells. METHODS: Membrane potentials and currents were measured by whole-cell patch clamp. Cytosolic calcium was measured using FURA-2 fluorescence. RESULTS: Insulin induced a gradual and reversible depolarization of 5.7+/-0.8 mV. Insulin-induced currents showed a linear slope conductance of 663 pS and a reversal potential of -17.9 mV. Ion substitution experiments showed that these currents were composed mainly of a nonselective cation component. In FURA-2 experiments, insulin caused a slow monophasic rise in HTC cell calcium, which depended on the presence of extracellular calcium. Insulin also induced significant increases of 1.58- and 1.54-fold in basal calcium influx when studied by external calcium withdrawal and readmission, or by the manganese quench method, respectively. Using the latter approach, we found that 100 microM gadolinium and 10 microM SKF96365 blocked the rise of the basal manganese quench rate induced by insulin whereas 100 microM verapamil was without effect. CONCLUSIONS: Insulin induces inward cation currents that depolarize HTC cell membrane potentials and participate in increased calcium influx.

Modulation of liver cell membrane NHE-1, Na+-K+ ATPase, and GLUT-2 protein content after cold preservation and rewarming.

Liver cell pH and volume regulation are perturbed by prolonged cold storage in University of Wisconsin solution and subsequent rewarming, but the molecular basis of this effect remains unknown. We prepared membranes from hepatocytes subjected to variable periods of cold preservation with or without subsequent rewarming and probed them by Western blotting with specific antibodies against the Na+ -H+ exchanger isoform NHE-1 and the Na+ -K+ ATPase alpha subunit. Results were compared with the content of GLUT-2, an abundant basolateral protein. NHE-1 decreased significantly as cold preservation times exceeded 10 h. Subsequent rewarming by short-term culture at 37 degrees C did not further reduce this parameter. On the other hand, expression of Na+ -K+ ATPase remained stable during cold storage times lasting up to 48 h, whereas rewarming resulted in a dramatic reduction in cells cold preserved beyond 10 h. In contrast, the membrane content of GLUT-2 was unaffected by cold preservation with or without subsequent rewarming. The results indicate that cold storage and rewarming respectively and selectively modulate the expression of specific hepatocellular membrane transport proteins.

Natriuretic peptides inhibit nicotine-induced whole-cell currents and catecholamine secretion in bovine chromaffin cells: evidence for the involvement of the atrial natriuretic factor R2 receptors.

There is increasing evidence that members of the natriuretic peptide family display sympathoinhibitory activity, but it remains uncertain which receptor pathway is implicated. We performed cyclic GMP production studies with chromaffin cells treated with either atrial natriuretic factor (ANF) or C-type natriuretic peptide (CNP) and found that these cells specifically express the ANF-R1C but not the ANF-R1A receptor subtype. Evidence for the existence of ANF-R2 receptors was obtained from patch-clamp experiments where C-ANF, an ANF-R2-specific agonist, inhibited nicotinic currents in single isolated chromaffin cells. Involvement of ANF-R2 receptors in the modulation of nicotinic currents was further supported by the significant loss of this inhibitory activity after the cleavage of the disulfide-bridged structure of C-ANF. This linearized form of C-ANF also displayed a lower binding affinity for ANF-R2 receptors. Like the patch-clamp studies, secretion experiments demonstrated that both CNP and C-ANF are equally effective in reducing nicotine-evoked catecholamine secretion by cultured chromaffin cells, raising the possibility that the effect of CNP is predominantly mediated by the ANF-R2 and not the ANF-R1C receptors. Finally, this response appears to be specific to nicotinic agonists because neither histamine- nor KCl-induced secretions were affected by natriuretic peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Different modulation of hepatocellular Na+/H+ exchange activity by insulin and EGF.

Indirect evidence suggests that insulin, like epidermal growth factor (EGF), stimulates liver cell Na+/H+ exchange. We directly studied the effect of insulin on intracellular pH (pHi) and the Na+/H+ exchanger in isolated rat hepatocytes with the fluorescent probe, 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). The effects of insulin were compared with those of EGF. Studies were carried out in the absence of HCO3- and in the presence of acetazolamide to isolate the Na+/H+ exchanger from other pH regulatory mechanisms. Insulin (9 nM) caused a reversible acidification of baseline pHi, whereas no significant effect was observed with EGF (30 nM). pHi was acidified by two different methods (NH4Cl pulse and external Na+ removal) to assess liver cell Na+/H+ exchange activity. In the NH4Cl pulse experiments, insulin had no significant effect on the Na+/H+ exchanger compared with the control (0.141 +/- 0.009 pH units/min, n = 14, and 0.122 +/- 0.023 pH units/min, n = 16, respectively). However, in the same conditions, EGF nearly doubled the rate of the Na+/H+ exchange activity (0.193 +/- 0.015 pH units/min, P < 0.05, n = 6). In the Na+ removal experiments, EGF again significantly increased the pHi recovery rate (0.542 +/- 0.032 pH units/min, n = 3) compared with the control (0.227 +/- 0.028 pH units/min, n = 5) and insulin (0.245 +/- 0.053 pH units/min, n = 5). Compared with control conditions, a subchronic administration of insulin (9 nM) in vitro had no significant effect on the Na+/H+ exchanger, nor did it affect baseline pHi.(ABSTRACT TRUNCATED AT 250 WORDS)