Changes in Gut Microbiota in Rats Fed a High Fat Diet Correlate with Obesity-Associated Metabolic Parameters

The gut microbiota is emerging as a new factor in the development of obesity. Many studies have described changes in microbiota composition in response to obesity and high fat diet (HFD) at the phylum level. In this study we used 16s RNA high throughput sequencing on faecal samples from rats chronically fed HFD or control chow (n = 10 per group, 16 weeks) to investigate changes in gut microbiota composition at the species level. 53.17% dissimilarity between groups was observed at the species level. Lactobacillus intestinalis dominated the microbiota in rats under the chow diet. However this species was considerably less abundant in rats fed HFD (P<0.0001), this being compensated by an increase in abundance of propionate/acetate producing species. To further understand the influence of these species on the development of the obese phenotype, we correlated their abundance with metabolic parameters associated with obesity. Of the taxa contributing the most to dissimilarity between groups, 10 presented significant correlations with at least one of the tested parameters, three of them correlated positively with all metabolic parameters: Phascolarctobacterium, Proteus mirabilis and Veillonellaceae, all propionate/acetate producers. Lactobacillus intestinalis was the only species whose abundance was negatively correlated with change in body weight and fat mass. This species decreased drastically in response to HFD, favouring propionate/acetate producing bacterial species whose abundance was strongly correlated with adiposity and deterioration of metabolic factors. Our observations suggest that these species may play a key role in the development of obesity in response to a HFD.     

High Energy Diets-Induced Metabolic and Prediabetic Painful Polyneuropathy in Rats

To establish the role of the metabolic state in the pathogenesis of polyneuropathy, an age- and sex-matched, longitudinal study in rats fed high-fat and high-sucrose diets (HFSD) or high-fat, high-sucrose and high-salt diets (HFSSD) relative to controls was performed. Time courses of body weight, systolic blood pressure, fasting plasma glucose (FPG), insulin, free fatty acids (FFA), homeostasis model assessment-insulin resistance index (HOMA-IR), thermal and mechanical sensitivity and motor coordination were measured in parallel. Finally, large and small myelinated fibers (LMF, SMF) as well as unmyelinated fibers (UMF) in the sciatic nerves and ascending fibers in the spinal dorsal column were quantitatively assessed under electron microscopy. The results showed that early metabolic syndrome (hyperinsulinemia, dyslipidemia, and hypertension) and prediabetic conditions (impaired fasting glucose) could be induced by high energy diet, and these animals later developed painful polyneuropathy characterized by myelin breakdown and LMF loss in both peripheral and central nervous system. In contrast SMF and UMF in the sciatic nerves were changed little, in the same animals. Therefore the phenomenon that high energy diets induce bilateral mechanical, but not thermal, pain hypersensitivity is reflected by severe damage to LMF, but mild damage to SMF and UMF. Moreover, dietary sodium (high-salt) deteriorates the neuropathic pathological process induced by high energy diets, but paradoxically high salt consumption, may reduce, at least temporarily, chronic pain perception in these animals.     

Zinc Supplementation Attenuates Metallothionein and Oxidative Stress Changes in Kidney of Streptozotocin-Induced Diabetic Rats

Zinc is an element that under physiological conditions preferentially binds to and is a potent inducer of metallothionein under physiological conditions. The present study was conducted to explore whether zinc supplementation morphologically and biochemically protects against diabetic nephropathy through modulation of kidney metallothionein induction and oxidative stress in streptozotocin-induced diabetic rats. Thirty-two Wistar albino male rats were equally divided into four groups. The first group was used as untreated controls and the second group was supplemented with 30?mg/kg/day zinc as zinc sulfate. The third group was treated with streptozotocin to induce diabetes and the fourth group was treated with streptozotocin and supplemented with zinc as described for group 2. The blood glucose and micro-albuminuria levels, body and kidney weights were measured during the 42-day experimental period. At the end of the experiment, the kidneys were removed from all animals from the four groups. Diabetes resulted in degenerative kidney morphological changes. The metallothionein immunoreactivity level was lower and the kidney lipid peroxidation levels were higher in the diabetes group than in the controls. The metallothionein immunoreactivity levels were higher in the tubules of the zinc-supplemented diabetic rats as compared to the non-supplemented diabetic group. The zinc and metallothionein concentrations in kidney tissue were higher in the supplemented diabetic group compared to the non-supplemented diabetes group. The activity of glutathione peroxidase did not change in any of the four groups. In conclusion, the present study shows that zinc has a protective effect against diabetic damage of kidney tissue through stimulation of metallothionein synthesis and regulation of the oxidative stress.     

Metabolic Changes Induced by Cold Stress in Rat Liver Mitochondria

The mechanisms involved in the metabolic changes induced by cold stress in isolated rat liver mitochondria were studied. Respiration, ATP synthesis, and membrane potential as well as the contents of several metabolites were determined in liver mitochondria from cold-exposed rats. At different times of cold exposure, the force-flux relationships showed net variation in flux (enhanced respiration, diminished ATP synthesis) with no associated variation in force (H+ gradient); this suggested that decoupling rather than classical uncoupling was involved in the effects of cold stress. The flux control coefficient of the H+ leak on basal respiration was slightly increased by 380 h of cold exposure. Cold stress also induced a diminution in total membrane fatty acids, Zn2+, Fe3+, ATP, and ADP/O ratios; the content of cytochromes c + c1 and b oscillated. The contents of Ca2+, Na+, Pi, and cytochromes a + a3 were not affected, whereas matrix ADP, AMP, K+, and Mg2+ were markedly increased. Basal and oleic acid-stimulated respiration of mitochondria from cold-stressed rats was inhibited by GDP, carboxyatractyloside, or albumin. These agents did not affect basal respiration in control mitochondria. Western blot analysis showed enhanced expression of a protein of about 35 kDa, presumably the uncoupling protein 2, induced by long-term cold exposure. The overall data suggest that cold stress promoted decoupling of oxidative phosphorylation, and hence, changes in several matrix metabolites, by increasing free fatty acids and the UCP2 content.     

Dietary Supplementation of Blueberry Juice Enhances Hepatic Expression of Metallothionein and Attenuates Liver Fibrosis in Rats

Aim

To investigate the effect of blueberry juice intake on rat liver fibrosis and its influence on hepatic antioxidant defense.

Methods

Rabbiteye blueberry was used to prepare fresh juice to feed rats by daily gastric gavage. Dan-shao-hua-xian capsule (DSHX) was used as a positive control for liver fibrosis protection. Liver fibrosis was induced in male Sprague-Dawley rats by subcutaneous injection of CCl₄ and feeding a high-lipid/low-protein diet for 8 weeks. Hepatic fibrosis was evaluated by Masson staining. The expression of α-smooth muscle actin (α-SMA) and collagen III (Col III) were determined by immunohistochemical techniques. The activities of superoxide dismutase (SOD) and malondialdehyde (MDA) in liver homogenates were determined. Metallothionein (MT) expression was detected by real-time RT-PCR and immunohistochemical techniques.

Results

Blueberry juice consumption significantly attenuates CCl₄-induced rat hepatic fibrosis, which was associated with elevated expression of metallothionein (MT), increased SOD activity, reduced oxidative stress, and decreased levels of α-SMA and Col III in the liver.

Conclusion

Our study suggests that dietary supplementation of blueberry juice can augment antioxidative capability of the liver presumably via stimulating MT expression and SOD activity, which in turn promotes HSC inactivation and thus decreases extracellular matrix collagen accumulation in the liver, and thereby alleviating hepatic fibrosis.     

Increased Systemic Level of Endotoxin Attenuates Baroreflex and Cardiovascular Effects of Infralimbic Cortex Electrostimulation in Anesthetized Rats

Journal of Evolutionary Biochemistry and Physiology - An increase in the level of endotoxin (bacterial lipopolysaccharide, LPS) leads to hypercytokinemia and the development of a systemic...     

去势大鼠新鲜、冷冻卵巢移植后激素代谢变化

目的观察去势大鼠经新鲜、冷冻卵巢移植后体内激素代谢变化情况。方法24只去势大鼠经右下腹皮下移植新鲜卵巢（3 d之内乳鼠卵巢）和经过冻存培养后的卵巢（3 d之内乳鼠卵巢）后,检测移植前、移植后1个月2、个月的三碘甲腺原氨酸（T3）、甲状腺素（T4）、促甲状腺激素（TSH）、睾酮（T）、雌二醇（E2）、孕酮（P）、黄体生成素（LH）及卵泡生成素（FSH）。结果冻存卵巢移植前与新鲜卵巢移植前比较：T值升高,有显著性差异（P〈0.01）;冻存卵巢移植后1个月与新鲜卵巢移植后1个月比较差异无显著性（P〉0.05）;冻存卵巢移植后2个月与新鲜卵巢移植后2个月比较：E2升高明显,差异具有显著性（P〈0.01;新鲜卵巢移植后2个月与移植前比较：T4,T,E2,P,LH均有明显升高（P〈0.01;P〈0.05）;冻存卵巢移植后2个月与移植前比较：E2,P增高明显（P〈0.01;P〈0.05）。结论冷冻卵巢移植较新鲜卵巢移植功能恢复明显。     

急性肝损伤大鼠模型的血浆氨基酸代谢变化模式

以Ｄ－氨基半乳糖（Ｄ－Ｇａｌａｃｔｏｓａｍｉｎｅ,Ｄ－ＧａｌＮ）造成急性肝损伤（急性肝炎、急性肝坏死）大鼠模型后、对照观察了急性肝损伤大鼠血浆氨基酸的变化,建立了大鼠急性肝损伤时血浆氨基酸的变化模式并对其发生机理进行了探讨。大鼠血浆氨基酸的测定采用聚酰薄层荧光分析技术,其测定结果是：急性肝炎组,酪氨酸（Ｔｙｒ）、天冬氨酸（Ａｓｐ）、谷氨酰胺（Ｇｌｎ）和鸟氨酸（Ｏｒｎ）升高,精氨酸（Ａｒｇ）下降,其余氨基酸无显著变化。急性肝坏死组,除Ａｒｇ显著下降外,其余所有氨基酸都显著升高,而两组支链氨基酸（ＢＣＡＡ）／芳香族氨基酸（ＡＡＡ）克分子比值均显著下降。     

Alleviation of Liver Dysfunction,Oxidative Stress,and Inflammation Underlines the Protective Effects of Polysaccharides from Cordyceps cicadae on High Sugar/High Fat Diet-Induced Metabolic Syndrome in Rats

This study investigated the protective effects of two polysaccharides (CPA-1 and CPB-2) from Cordyceps cicadae against high fructose/high fat diet (HF/HFD) induced obesity and metabolic disorders in rats. Rats were either fed with normal diet or HF/HFD and treated with CPA-1 and CPB-2 (100 and 300 mg/kg) for 11 weeks. Administration of CPA-1 and CPB-2 significantly and dose dependently reduced body and liver weight, insulin and glucose tolerance, serum insulin and glucose levels. Furthermore, serum and hepatic lipid profiles, liver function enzymes and proinflammatory cytokines (TNF-α, IL-1β and IL-6) were markedly reduced. Additionally, CPA-1 and CPB-2 treatment alleviated hepatic oxidative stress by reducing lipid peroxidation level (MDA) and upregulating glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) activities as well as ameliorated histological alterations through the reduction of hepatic lipid accumulation. These results suggested that the polysaccharides from C. cicadae showed protective effects against HF/HFD induced metabolic disturbances and may be considered as a dietary supplement for treating obesity.     

Changes in Superoxide Dismutase Activity in Liver and Lung of Old Rats

Superoxide dismutase activity was measured in liver and lung from 3 and 24 month-old rats. Both total SOD and Mn-SOD activity decreased significantly in the liver of old rats. Recent results from our laboratory have indicated that during aging, the activity of Cu/Zn-SOD decreases in rat liver and that there is an accumulation of altered protein. It was also shown that the old Cu/Zn-SOD had one histidine fewer than the young one. In the present study, the immunoprecipitation experiments showed that the amount of immunoprecipitable Mn-SOD from liver of old rats was greater than from young ones, but when amino acid residues were measured in purified young and old Mn-SOD from liver, no change was observed. In lung, no significant age-related differences in total SOD, Cu/Zn-SOD and Mn-SOD activity were found, nor was there accumulation of altered protein during aging.     

Changes in Superoxide Dismutase Activity in Liver and Lung of Old Rats

Superoxide dismutase activity was measured in liver and lung from 3 and 24 month-old rats. Both total SOD and Mn-SOD activity decreased significantly in the liver of old rats. Recent results from our laboratory have indicated that during aging, the activity of Cu/Zn-SOD decreases in rat liver and that there is an accumulation of altered protein. It was also shown that the old Cu/Zn-SOD had one histidine fewer than the young one. In the present study, the immunoprecipitation experiments showed that the amount of immunoprecipitable Mn-SOD from liver of old rats was greater than from young ones, but when amino acid residues were measured in purified young and old Mn-SOD from liver, no change was observed. In lung, no significant age-related differences in total SOD, Cu/Zn-SOD and Mn-SOD activity were found, nor was there accumulation of altered protein during aging.     

Embelin Attenuates Intracerebroventricular Streptozotocin-Induced Behavioral,Biochemical, and Neurochemical Abnormalities in Rats

Embelin, the main active constituent of Embelia ribes, has been reported to possess various pharmacological actions, including anti-inflammatory, antioxidant, anticonvulsant, and neuroprotective. The present study was designed to investigate neuroprotective mechanisms and therapeutic potential of embelin against intracerebroventricular streptozotocin (ICV-STZ)-induced experimental sporadic dementia in rats. STZ was infused bilaterally at the dose of (3 mg/kg/1 μl/1 min) ICV on day first and third. Spatial and non-spatial memory was evaluated using Morris water maze and object recognition task in rats. Embelin (2.5, 5, and 10 mg/kg, i.p.) was administrated for 14 days from seventh day onwards after first ICV-STZ infusion in rats. On day 22, rats were sacrificed and hippocampal brain regions were used to identify biochemical, neurochemical, and neuroinflammatory alterations. STZ-infused rats showed significant learning and memory deficit which was associated with an increase in oxidative stress (lipid peroxidation and nitrite), compromised antioxidant defense (reduced glutathione), neurotransmitter alterations (AChE, dopamine, noradrenaline, 5-hydroxytryptamine, gama amino butyric acid, and glutamate), and elevation in neuroinflammatory cytokine (IL-1 β, IL-6, and TNF-α) levels. Embelin dose dependently attenuated STZ-induced cognitive deficit and biochemical alterations and restored hippocampal neurochemical levels. The observed protective effect might be attributed to the antioxidant and anti-inflammatory potential of embelin and its ability to restore hippocampal neurochemistry. Thus, the outcomes of the current study suggest therapeutic potential of embelin in cognitive disorders such as sporadic Alzheimer’s disease (SAD).     

High Glucose Attenuates Shear-Induced Changes in Endothelial Hydraulic Conductivity by Degrading the Glycocalyx

Diabetes mellitus is a risk factor for cardiovascular disease; however, the mechanisms through which diabetes impairs homeostasis of the vasculature have not been completely elucidated. The endothelium interacts with circulating blood through the surface glycocalyx layer, which serves as a mechanosensor/transducer of fluid shear forces leading to biomolecular responses. Atherosclerosis localizes typically in regions of low or disturbed shear stress, but in diabetics, the distribution is more diffuse, suggesting that there is a fundamental difference in the way cells sense shear forces. In the present study, we examined the effect of hyperglycemia on mechanotranduction in bovine aortic endothelial cells (BAEC). After six days in high glucose media, we observed a decrease in heparan sulfate content coincident with a significant attenuation of the shear-induced hydraulic conductivity response, lower activation of eNOS after exposure to shear, and reduced cell alignment with shear stress. These studies are consistent with a diabetes-induced change to the glycocalyx altering endothelial response to shear stress that could affect the distribution of atherosclerotic plaques.     

Fuzi Attenuates Diabetic Neuropathy in Rats and Protects Schwann Cells from Apoptosis Induced by High Glucose

Radix aconite lateralis preparata (Fuzi), a folk medicine, has long been used for the treatment of diabetes and paralysis in China. We examined the effect of Fuzi alone on diabetic rats and Schwann cells in high glucose and the components responsible for its activity. The major constituents of FZE were identified by HPLC-MS/MS data. Male Sprague Dawley rats (n = 36) were randomly divided into control, diabetic, FZE 1.75 g/kg, FZE 3.50 g/kg, FZE 7.00 g/kg, and methylcobalamin groups. After two weeks treatment, nerve conduction velocity and paw withdrawal latency were measured. In vitro, the Schwann cells were grouped according to exposure: normal glucose (NG), normal glucose plus mannitol (NG+M), high glucose (HG), and HG plus different concentrations of FZE (0.1 µg/ml, 1.0 µg/ml, and 10.0 µg/ml). Oxygen free radicals and apoptosis were evaluated through DCFH₂DA, DHE and annexin-PE/7-AAD assay, respectively. Apoptosis factors (Bax, Bcl-2, CytoC, caspase-3, and caspase-9) were analyzed using immunofluorescence. Nine alkaloids were identified. The results from animal model showed that FZE was effective in accelerating nerve conduction velocity and shortening paw withdrawal latency in diabetic rats. And in vitro, FZE was also found to protect Schwann cells against high glucose injury. FZE could significantly decrease the apoptotic ratio, superoxide anion and peroxide level. Furthermore, the apoptosis factors, including Bax, Bcl-2, CytoC, caspase-3, and caspase-9 were ameliorated in FZE treated groups. The HPLC-MSⁿ method is simple and suitable for the identification of alkaloids in Fuzi. FZE has a protective effect in diabetic neuropathic rats, which is probably achieved by the antiapoptotic effect of FZE on Schwann cells. Apoptosis factor data imply that FZE protected Schwann cells through the mitochondria pathway. Alkaloids are major components contributing to the protective effect.     

Piperine,a Natural Bioenhancer,Nullifies the Antidiabetic and Antioxidant Activities of Curcumin in Streptozotocin-Diabetic Rats

Knowing that curcumin has low bioavailability when administered orally, and that piperine has bioenhancer activity by inhibition of hepatic and intestinal biotransformation processes, the aim of this study was to investigate the antidiabetic and antioxidant activities of curcumin (90 mg/kg) and piperine (20 or 40 mg/kg), alone or co-administered, incorporated in yoghurt, in streptozotocin (STZ)-diabetic rats. The treatment for 45 days of STZ-diabetic rats with curcumin-enriched yoghurt improved all parameters altered in this experimental model of diabetes: the body weight was increased in association with the weight of skeletal muscles and white adipose tissues; the progressive increase in the glycemia levels was avoided, as well as in the glycosuria, urinary urea, dyslipidemia, and markers of liver (alanine and aspartate aminotransferases and alkaline phosphatase) and kidney (urinary protein) dysfunction; the hepatic oxidative stress was decreased, since the activities of the antioxidant enzymes superoxide dismutase, catalase and gluthatione peroxidase were increased, and the levels of malondialdehyde and protein carbonyl groups were reduced. The dose of 20 mg/kg piperine also showed antidiabetic and antioxidant activities. The treatment of STZ-diabetic rats with both curcumin and 20 mg/kg piperine in yoghurt did not change the antidiabetic and antioxidant activities of curcumin; notably, the treatment with both curcumin and 40 mg/kg piperine abrogated the beneficial effects of curcumin. In addition, the alanine aminotransferase levels were further increased in diabetic rats treated with curcumin and 40 mg/kg piperine in comparison with untreated diabetic rats. These findings support that the co-administration of curcumin with a bioenhancer did not bring any advantage to the curcumin effects, at least about the antidiabetic and antioxidant activities, which could be related to changes on its biotransformation.     

Influence of Dietary Carbohydrate,Fat, and Protein on Lipogenesis in Rats

The incorporation of ¹⁴C of acetate-1-¹⁴C into the lipids of the liver and carcass, and the changes in the concentrations of nucleotides and citric acid in the liver were studied in the rats fed individual nutrients; starch, casein or corn oil. And the metabolism of citric acid-1,5-¹⁴C was also investigated after the feeding of nutrients. Lipogenesis in the liver and carcass was more markedly stimulated with starch than with casein or corn oil. In the liver of rats fed starch, the concentration of ATP doubled and that of citric acid was one-half of those with casein or corn oil, respectively. And the conversion of citric acid to carbon dioxide and lipids was stimulated with starch.     

Piperine Reverses Chronic Unpredictable Mild Stress-Induced Behavioral and Biochemical Alterations in Rats

Previous studies in our laboratory have demonstrated that piperine produced antidepressant-like action in various mouse models of behavioral despair, which was related to the serotonergic system. The present study aimed to examine the behavioral and biochemical effects of piperine in rats exposed to chronic unpredictable mild stress (CUMS). The results showed that CUMS caused depression-like behavior in rats, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test. In addition, it was found that serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) contents in the hippocampus and frontal cortex were significantly decreased in CUMS-treated rats. Treating the animals with piperine significantly suppressed behavioral and biochemical changes induced by CUMS. The results suggest that piperine produces an antidepressant-like effect in CUMS-treated rats, which is possibly mediated by increasing 5-HT and BDNF contents in selective brain tissues.