Trigonelline Inhibits Inflammation and Protects ß Cells to Prevent Fetal Growth Restriction during Pregnancy in a Mouse Model of Diabetes.

BACKGROUND: As an active component from traditional Chinese medicine, trigonelline has a protective effect on diabetes. This study evaluated the protective effects of trigonelline on diabetic mice during pregnancy. METHODS: Diabetes was induced in female mice by intraperitoneal injection for continuous 5-day of 40 mg/kg/day streptozotocin. Female mice were divided into 4 groups after they were allowed to mate with normal male mice: nondiabetic, nondiabetic treated with trigonelline (70 mg/kg) for 18 days, diabetic, and diabetic treated with trigonelline (70 mg/kg). RESULTS: Diabetic pregnant mice had significantly higher levels of blood glucose, serum total cholesterol, triglyceride, insulin, and leptin but lower serum omentin-1 level and insulin sensitivity index than the nondiabetic ones. Trigonelline improved the hyperglycemia, dyslipidemia, insulin resistance, and adipocytokine of diabetic pregnant mice. Diabetic pregnant mice had significantly reduced fetus numbers, fetal weight, and fetal/placental ratio, which were reversed by trigonelline. Trigonelline prevented the increase in proinflammatory cytokines and reduced interleukin-10 level in placenta of diabetic pregnant mice. Trigonelline increased ß-cell replication and the decreased ß-cell mass, and decreased the ß-cell apoptosis of diabetic pregnant mice. CONCLUSION: These findings suggest that trigonelline protects diabetic pregnancy partly by suppressing inflammation, regulating the secretion of adipocytokines, increasing ß-cell mass, replication, and decreasing ß-cell apoptosis.

Effects of rhynchophylline on GluN1 and GluN2B expressions in primary cultured hippocampal neurons.

N-methyl-d-aspartate (NMDA) receptor subunits GluN1 and GluN2B in hippocampal neurons play key roles in anxiety. Our previous studies show that rhynchophylline, an active component of the Uncaria species, down-regulates GluN2B expression in the hippocampal CA1 area of amphetamine-induced rat. The effects of rhynchophylline on expressions of GluN1 and GluN2B in primary hippocampal neurons in neonatal rats in vitro were investigated. Neonatal hippocampal neurons were cultured with neurobasal-A medium. After incubation for 6h or 48 h with rhynchophylline (non-competitive NMDAR antagonist) and MK-801 (non-competitive NMDAR antagonist with anxiolytic effect, as the control drug) from day 6, neuron toxicity, mRNA and protein expressions of GluN1 and GluN2B were analyzed. GluN1 is mainly distributed on neuronal axons and dendritic trunks, cytoplasm and cell membrane near axons and dendrites. GluN2B is mainly distributed on the membrane, dendrites, and axon membranes. GluN1 and GluN2B are codistributed on dendritic trunks and dendritic spines. After 48 h incubation, a lower concentration of rhynchophylline (lower than 400 µmol/L) and MK-801 (lower than 200 µmol/L) have no toxicity on neonatal hippocampal neurons. Rhynchophylline up-regulated GluN1 mRNA expression at 6h and mRNA and protein expressions at 48h, but down-regulated GluN2B mRNA and protein expressions at 48 h. However, GluN1 and GluN2B mRNA expressions were down-regulated at 6h, and mRNA and protein expressions were both up-regulated by MK-801 at 48h. These findings show that rhynchophylline reciprocally regulates GluN1 and GluN2B expressions in hippocampal neurons, indicating a potential anxiolytic property for rhynchophylline.

Omentin: linking metabolic syndrome and cardiovascular disease.

Omentin is an adipokine preferentially produced by visceral adipose tissue with insulin-sensitizing effects. Its expression is reduced in obesity, insulin resistance and type 2 diabetes. Omentin is also positively related with adiponectin, high-density lipoprotein levels and negatively related with body mass index, waist circumference, insulin resistance, triglyceride and leptin levels. Lower plasma omentin levels contribute to the pathogenesis of insulin resistance, type 2 diabetes and cardiovascular diseases in obese or overweight patients. Omentin has anti-inflammatory, antiatherogenic, anti-cardiovascular disease and antidiabetic properties. With respect to vascular biology, omentin causes vasodilatation of blood vessels and attenuates C-reactive protein-induced angiogenesis. The ability of omentin to reduce insulin resistance in conjunction with its anti-inflammatory and anti-atherogenic properties makes it a promising therapeutic target. Thus, omentin may have beneficial effects on the metabolic syndrome and could potentially be used as a biologic marker and/or pharmacologic agent/target in this respect.

Individual and combined effects of rhynchophylline and ketamine on proliferation, NMDAR1 and GluA2/3 protein expression in PC12 cells.

Rhynchophylline is an active component of the Uncaria species, which is a member of the Rubiaceae family. Our studies show that the downregulation of N-methyl-d-aspartate (NMDA) receptor subunit GluN2B expression in the nucleus accumbens, amygdala, medial prefrontal cortex, and hippocampal CA1 area by rhynchophylline is beneficial for the treatment of psychological dependence on amphetamines. The individual and combined effects of rhynchophylline and ketamine on proliferation and GluN1 and GluA2/3 protein expression in PC12 cells were investigated. PC12 cells were differentiated into neuron-like cells by treatment with nerve growth factor (50 ng/mL). After treatment for 48 h, differentiated PC12 cell proliferation and GluN1 and GluA2/3 protein expression were analyzed. The viability of PC12 cells was reduced by ketamine at doses of 0.50, 1.00, 1.50, and 2.00 mmol/L, with the viability of cells treated with 1.50 and 2.00 mmol/L of ketamine significantly lower than that of the control cells. However, PC12 cells treated with rhynchophylline showed no toxicity at doses of 0.25, 0.50, 0.75, or 1.00 mmol/L. While GluA2/3 protein expression was upregulated by ketamine, it was not influenced by rhynchophylline. GluN1 protein expression was downregulated by rhynchophylline (1 mmol/L), while treatment with ketamine, either alone or with rhynchophylline, had no effect. These findings demonstrate that rhynchophylline suppresses GluA2/3 expression in ketamine-induced PC12 cells and downregulates GluN1 expression. Ketamine's lack of effect on GluN1 expression offers a partial explanation for ketamine addiction and the anti-addictive properties of rhynchophylline.

Protective effect of total flavonoids of seabuckthorn (Hippophae rhamnoides) in simulated high-altitude polycythemia in rats.

Seabuckthorn (Hippophae rhamnoides L.) has been used to treat high altitude diseases. The effects of five-week treatment with total flavonoids of seabuckthorn (35, 70, 140 mg/kg, ig) on cobalt chloride (5.5 mg/kg, ip)- and hypobaric chamber (simulating 5,000 m)-induced high-altitude polycythemia in rats were measured. Total flavonoids decreased red blood cell number, hemoglobin, hematocrit, mean corpuscular hemoglobin levels, span of red blood cell electrophoretic mobility, aggregation index of red blood cell, plasma viscosity, whole blood viscosity, and increased deformation index of red blood cell, erythropoietin level in serum. Total flavonoids increased pH, pO2, Sp(O2), pCO2 levels in arterial blood, and increased Na⁺, HCO3⁻, Cl⁻, but decreased K⁺ concentrations. Total flavonoids increased mean arterial pressure, left ventricular systolic pressure, end-diastolic pressure, maximal rate of rise and decrease, decreased heart rate and protected right ventricle morphology. Changes in hemodynamic, hematologic parameters, and erythropoietin content suggest that administration of total flavonoids from seabuckthorn may be useful in the prevention of high altitude polycythaemia in rats.

Hypoglycemic and Hypolipidemic Effects of Ethanolic Extract of Mirabilis jalapa L. Root on Normal and Diabetic Mice.

The present study investigated the insulin sensitivity, hypoglycemic, and hypolipidemic activities of ethanolic extract of Mirabilis jalapa L. root (EEM) in normal and diabetic mice. After induction of diabetes with streptozotocin, both normal and diabetic mice were singly or repeatedly for 28 days administrated with EEM at doses of 2, 4, 8 g/kg, respectively. Before induction of diabetes, mice were administrated with EEM at doses of 2, 4, 8 g/kg for 14 days and were injected with streptozotocin and continued on EEM administration for another 28 days. Both after and before induction of diabetes, repeated administration with 4, 8 g/kg EEM continually lowered blood glucose level, decreased serum insulin level and improved insulin sensitivity index, and lowered serum total cholesterol, triglyceride levels and triglyceride content in liver and skeletal muscle, and increased glycogen content in these tissues; but repeated administration had no influence on those indexes of normal mice. Single administration with EEM (4, 8 g/kg) showed hypoglycemic effect in oral glucose tolerance test in normal and diabetic mice. Single administration with EEM had no hypoglycemic and hypolipidemic effects on normal and diabetic mice. These results suggest that EEM possesses both potential insulin sensitivity, hypoglycemic, and hypolipidemic effects on diabetes.

Isorhynchophylline: A plant alkaloid with therapeutic potential for cardiovascular and central nervous system diseases.

Uncaria species (Gouteng in Chinese) have been used as a plant medicine to treat ailments of cardiovascular and central nervous systems. As the main alkaloid constituent of Uncaria species, isorhynchophylline has drawn extensive attention toward antihypertensive and neuroprotective activities in recent years. Isorhynchophylline mainly acts on cardiovascular and central nervous systems diseases including hypertension, brachycardia, arrhythmia, and sedation, vascular dementia, and amnesia. Isorhynchophylline also has effects on anticoagulation, inhibition vascular smooth muscle cell apoptosis and proliferation, anti-multidrug resistant of lung cells, anti-endotoxemic, and antispasmodic. The active mechanisms are related to modulation on calcium ion channel, protection neural and neuroglial cells against ß-amyloid(25-35)-induced neurotoxicity and via inducing autophagy. As a candidate drug of several cardiovascular and central nervous systems diseases, isorhynchophylline will attract scientists to pursue the potential related pharmacological effects and its mechanism with new technologies. But relatively few clinical application of isorhynchophylline has been conducted on its pharmacological activities. It requires more in vivo validations and further investigations of antihypertensive and neuroprotective mechanisms of isorhynchophylline.

Protection of trigonelline on experimental diabetic peripheral neuropathy.

The mechanisms leading to diabetic peripheral neuropathy are complex and there is no effective drug to treat it. As an active component of several traditional Chinese medicines, trigonelline has beneficial effects on diabetes with hyperlipidemia. The protective effects and the mechanism of trigonelline on diabetic peripheral neuropathy were evaluated in streptozotocin- and high-carbohydrate/high-fat diet-induced diabetic rats. Rats were divided into four groups at the end of week 2: control, diabetes, diabetes + trigonelline (40 mg/kg), and diabetes + sitagliptin (4 mg/kg). After 48-week treatment, technologies of nerve conduction, cold and hot immersion test, transmission electron microscopy, real-time PCR, and Western blotting were applied. Serum glucose, serum insulin, insulin sensitivity index, lipid parameters, body weight, sciatic nerve conduction velocity, nociception, glucagon-like peptide-1 receptor mRNA and protein, total and phosphorylated p38 mitogen-activated protein kinases protein expression, malonaldehyde content, and superoxide dismutase activity were altered in diabetic rats, and were near control levels treated with trigonelline. Slight micropathological changes existed in sciatic nerve of trigonelline-treated diabetic rats. These findings suggest that trigonelline has beneficial effects for diabetic peripheral neuropathy through glucagon-like peptide-1 receptor/p38 mitogen-activated protein kinases signaling pathway, nerve conduction velocity, antioxidant enzyme activity, improving micropathological changes of sciatic nerve and decreasing lipid peroxidation.

Resveratrol protects against hyperglycemia-induced oxidative damage to mitochondria by activating SIRT1 in rat mesangial cells.

Oxidative stress and mitochondrial dysfunction are involved in the pathogenesis of diabetic nephropathy (DN). Resveratrol has potent protective effects on diabetes and diabetic complications including diabetic nephropathy. We aimed to investigate the protective effects of resveratrol on mitochondria and the underlying mechanisms by using an in vitro model of hyperglycemia. We exposed primary cultured rat mesangial cells to high glucose (30mM) for 48h. We found that pretreatment with resveratrol (10µM) 6h prior to high glucose treatment significantly reduced hyperglycemia-induced increase in reactive oxygen species (ROS) production and mitochondrial superoxide generation, as well as stimulated MnSOD activity. In addition, resveratrol pretreatment significantly reversed the decrease of mitochondrial complex III activity in glucose-treated mesangial cells, which is considered to be the major source of mitochondrial oxidative stress in glucose-treated cells. Furthermore, resveratrol pretreatment efficiently restored the hyperpolarization of ∆Ψm, increased ATP production and preserved the mtDNA content. All of these protective effects of resveratrol were successfully blocked by siRNA targeting SIRT1 and EX-527, a specific inhibitor of SIRT1 activity. Our results indicated that resveratrol efficiently reduced oxidative stress and maintained mitochondrial function related with activating SIRT1 in glucose-treated mesangial cells. It suggested that resveratrol is pharmacologically promising for treating diabetic nephropathy.

Protective effect of berberine on antioxidant enzymes and positive transcription elongation factor b expression in diabetic rat liver.

The protective effect of berberine against antioxidant, antilipid peroxidation in serum and liver tissue, and positive transcription elongation factor b (P-TEFb) expression in liver tissue of type 2 diabetic rats was investigated. Overnight fasted rats were intraperitoneally injected 35 mg/kg streptozotocin. Diabetic rats were admitted after 2 weeks and given a high-carbohydrate/high-fat diet to induce hyperlipidemias. From week 16, diabetic rats were treated with 75, 150, 300 mg/kg berberine, 100mg/kg fenofibrate or 4 mg/kg rosiglitazone for another 16 weeks. P-TEFb (composed of cyclin-dependent kinase 9 and cyclin T1) mRNA and protein expression in liver tissue were detected by real time PCR and immunohistochemistry, respectively. Berberine significantly up-regulated the declined cyclin-dependent kinase 9, cyclin T1 mRNA and protein expression in diabetic rat liver. Berberine obviously decreased malondialdehyde level and increased catalase, superoxide dismutase, glutathione peroxidase, and glutathione activities in liver tissue and serum of diabetic rats. These results suggest that the effects of berberine on up-regulation of P-TEFb expression, antioxidant and antilipid peroxidation may be related to its protective potential on diabetes.

Orexigenic effect of cocaine- and amphetamine-regulated transcript (CART) after injection into hypothalamic nuclei in streptozotocin-diabetic rats.

1. The aim of the present study was to investigate the orexigenic effect of cocaine- and amphetamine-regulated transcript (CART) peptide on feeding regulation following its injection into discrete nuclei of the hypothalamus. 2. Male Sprague-Dawley diabetic rats were injected with 0.06 or 0.2 nmol CART (55-102) or an equal volume of saline into various hypothalamic areas and food intake was then measured 1, 2, 4, 8 and 24 h after injection. Changes in hypothalamic CART mRNA expression in response to dietary intervention (2 weeks feeding of a high-fat diet) were assessed using quantitative real-time reverse transcription-polymerase chain reaction. Possible interactions between neuropeptide Y (NPY), agouti-related protein (AGRP), α-melanocyte-stimulating hormone (MSH) and corticotropin-releasing hormone (CRH) were evaluated in an in vitro hypothalamic explant system. Neuropeptide immunoreactivities (IR) were determined using radioimmunoassays (RIAs). 3. At 0.2 nmol, CART (55-102) significantly increased feeding in fasted diabetic rats after injection into the dorsomedial hypothalamic nucleus and arcuate nucleus (ARC). Injection of 0.2 nmol CART (55-102) into the ARC of satiated diabetic rats also increased food intake that was similar in both magnitude and time-course to the response seen in fasted diabetic rats. Food intake in diabetic rats on a high-fat diet was clearly increased after injection of 0.2 nmol CART (55-102) into the ARC, as was CART mRNA expression. Incubation of hypothalamic explants with 0.4, 4 and 40 nmol/L CART (55-102) for 45 min significantly increased NPY IR, whereas exposure of explants to 4 nmol/L CART (55-102) increased AGRP IR and CRH IR. None of the concentrations of CART (55-102) tested had any effect on α-MSH IR. 4. Together, these data provide further evidence that hypothalamic CART has an orexigenic effect, which, in the ARC, may stimulate the release of hypothalamic orexigenic neuropeptides.

Effect of rhynchophylline on central neurotransmitter levels in amphetamine-induced conditioned place preference rat brain.

The effects of rhynchophylline on expression of amphetamine reward using a conditioned place preference (CPP) paradigm and central neurotransmitter levels in rat brain was investigated. Rats were injected with amphetamine (2 mg/kg, per day for 4 consecutive days) and treated with rhynchophylline (60 mg/kg, per day for the later 3 days). Control rats were administered with rhynchophylline (60 mg/kg) instead of amphetamine to evaluate whether rhynchophylline by itself produced CPP. Glutamic acid, γ-aminobutyric acid, endorphin, acetylcholine, norepinephrine, dopamine, and 5-hydroxytryptamine contents were examined by encephalofluogram technology. Rhynchophylline reversed the expression of amphetamine-induced CPP and itself did not produce a CPP. Glutamic acid, dopamine, and norepinephrine contents in amphetamine-CPP rat brain were significantly higher; while γ-aminobutyric acid, endorphin, and acetylcholine contents were significantly lower than those of control rats. Rhynchophylline reversed those central neurotransmitter levels induced by amphetamine to control levels; rhynchophylline by itself had no effect on central neurotransmitter in control rats. These findings show that rhynchophylline reverses the expression of amphetamine-induced rewarding effect which is partly mediated by regulation of central neurotransmitter levels in the rat brain.

Rhynchophylline down-regulates NR2B expression in cortex and hippocampal CA1 area of amphetamine-induced conditioned place preference rat.

N-methyl-D-aspartate receptor 2B subunit (NR2B) has an important role in the development of conditioned place preference (CPP) and psychostimulant abuse. Rhynchophylline is presently used to treat central nervous systems diseases and has a non-competitive antagonistic effect on NMDA receptors. In this study, amphetamine was administered in rats (2 mg/kg, s.c., once each day for 4 consecutive days), during which they were treated with rhynchophylline (60 mg/kg, i.p., once each day for the next 3 days). NR2B mRNA and protein expression were examined by in situ hybridization and immunohistochemistry. CPP was induced by amphetamine (2 mg/kg, s.c.) by 4th day in rats. Rhynchophylline effectively reversed the expression of amphetamine-induced CPP and itself did not produce a CPP. Amphetamine-CPP rats showed a significantly increased NR2B mRNA and protein expression in medial prefrontal cortex and hippocampal CA1 areas as compared to the control group. Rhynchophylline reversed NR2B mRNA and protein levels induced by amphetamine but rhynchophylline by itself had no effect on NR2B expression in control rats. These results indicate that rhynchophylline inhibits the expression of amphetamine-induced rewarding effect, and this action might be related to down-regulation of NR2B expression in medial prefrontal cortex and hippocampal CA1 area.

Chronic effects of berberine on blood, liver glucolipid metabolism and liver PPARs expression in diabetic hyperlipidemic rats.

Berberine is one of the main alkaloids of Rhizoma coptidis which has been used as a folk medicine to treat diabetes mellitus for more than 1400 years in China. To investigate the chronic effect of berberine on diabetic hyperlipidemic rats, fasted rats were intraperitoneally injected 35 mg/kg streptozotocin. Diabetic rats were admitted after 2 weeks and given a high-carbohydrate/high-fat diet to induce hyperlipidemia. The rats were divided into 7 groups at the end of week 16: normal and diabetic rats received no drug, 5 treatment groups were administered with either 75, 150, 300 mg/kg berberine, 100 mg/kg fenofibrate or 4 mg/kg rosiglitazone per day for 16 weeks, respectively. The blood glucose, hemoglobin A1c, lipid metabolic parameters and hepatic glycogen and triglyceride were measured, and histopathology and peroxisome proliferator-activated receptors (PPARs) alpha/delta/gamma expression of liver were determined by hematoxylin eosin and immunohistochemical staining. Berberine reduced diabetic rats' body weight, liver weight and liver to body weight ratio. Berberine restored the increased blood glucose, hemoglobin A1c, total cholesterol, triglyceride, low density lipoprotein-cholesterol, apolipoprotein B and the decreased high density lipoprotein-cholesterol, apolipoprotein AI levels in diabetic rats to near the control ones. Berberine alleviated the pathological progression of liver and reverted the increased hepatic glycogen and triglyceride to near the control levels. Berberine increased PPARalpha/delta expression and reduced PPARgamma expression in liver of diabetic rat to near the control ones. Berberine improved glucolipid metabolism both in blood and liver in diabetic rats possibly through modulating the metabolic related PPARalpha/delta/gamma protein expression in liver.

Effect of berberine on PPARalpha/delta/gamma expression in type 2 diabetic rat retinae.

Retinopathy is a major cause of morbidity in diabetes and remains the primary cause of new blindness. Therefore, it is necessary to find new drug to treat diabetic retinopathy. Type 2 diabetes mellitus (T2DM) rats were induced by injection (ip) with streptozotocin (STZ) 35 mg x kg(-1) and fed with a high-carbohydrate/high-fat diet 2 weeks later. From week 17 to 32, diabetic rats were given different doses of berberine 75, 150, and 300 mg x kg(-1), fenofibrate 100 mg x kg(-1) and rosiglitazone 4 mg x kg(-1), separately. Retinal structure was observed with hematoxylin-eosin staining and peroxisome proliferator-activated receptors (PPARs) alpha/delta/gamma protein expressions were detected by immunohistochemistry. The retina of control rats was thicker than that of other groups, 16 weeks treatment with berberine (150 and 300 mg x kg(-1)) and rosiglitazone 4 mg x kg(-1) thickened the diabetic retina, but no difference existed in retinal structure among groups. Both berberine (150 and 300 mg x kg(-1)) and rosiglitazone 4 mg x kg(-1) significantly decreased PPARy expression in diabetic retina; while berberine (150 and 300 mg x kg(-1)) and fenofibrate 100 mg x kg(-1) obviously increased both PPARalpha and PPARdelta expressions in diabetic retina. Berberine modulates PPARalpha/delta/gamma protein levels in diabetic retina which may contribute to ameliorate retinopathy complication induced by STZ and a high-carbohydrate/high-fat diet. It is expected that berberine might be a more beneficial drug to treat diabetic retinal complication comparing with fenofibrate and rosiglitazone.

[Effects of Caulis Sinomenii and sinomenine on morphine-induced place preference and brain histamine level in mice].

OBJECTIVE: To evaluate the effects of Caulis Sinomenii and sinomenine on conditioned place preference (CPP) induced by morphine and brain histamine level in mice. METHODS: Sixty mice were randomized into 6 equal groups and morphine (Mor) was injected subcutaneously (9 mg/kg) for 6 consecutive days to induce CPP using a shuttle box. Since the 4th day of training, the mice in 5 of the groups were treated for 3 consecutive days with Caulis Sinomenii (10 g/kg), sinomenine (60 mg/kg), diphenhydramine (30 mg/kg), CP48/80 (5 mg/kg) and L-histidine (750 mg/kg) in addition to morphine (9 mg/kg) treatment, respectively, leaving the other group with exclusive morphine treatment. Another 10 mice received saline injection to serve as saline control group. The content of histamine (HA) in the mouse brain was measured by fluorospectrophotometry. RESULTS: In morphine group, the mice showed significantly extended stay in morphine-paired compartment whose HA content in the brain was markedly increased (P<0.01). Treatment with Caulis Sinomenii and sinomenine resulted in significantly reduced time of stay in morphine-paired compartment and brain HA level (P<0.01). CONCLUSION: CPP induced by morphine in mice is associated with increased HA level in the brain. Caulis Sinomenii and sinomenine can suppress the acquisition of place preference induced by morphine and modulate HA level in the central nervous system in morphine-dependent mice.