藏药小檗皮对糖尿病模型小鼠血糖水平影响的初步研究

目的:观察藏药小檗皮对糖尿病小鼠模型及正常小鼠血糖的影响,并以血糖为指标确定其治疗糖尿病及其并发症的有效剂量范围.方法:以6.72 9·kg-1、3.36 9·kg-1、1.68 g·kg-1、0.84 9·kg-1、0.42 g.· kg-1剂量的小檗皮浸膏灌胃四氧嘧啶糖尿病小鼠10d,GOD-CE-PAP法测定小鼠血糖水平,以确定小檗皮的有效降糖剂量范围;6.72 g·kg-1、1.68 g·kg-1、0.84 g·kg-1剂量的小檗皮浸膏灌胃正常小鼠7d,GOD-CE-PAP法测定小鼠血糖水平,观察小檗皮对正常小鼠血糖的影响.结果:与模型对照组相比,盐酸二甲双胍、盐酸小檗碱、生物碱复配及6.72 g·kg-1、1.68 9·k-1、0.84 9·kg-1、3.36 g·kg-1、0.42 g·kg-1的小檗皮浸膏均有较好的降糖作用,5个剂量的小檗皮浸膏降糖作用依次为:6.72 9·kg-1＞ 1.689·kg-1＞ 0.849·kg-1＞3.36 g·kg-1＞0.429·kg-1;盐酸二甲双胍、羟苯磺酸钙、盐酸小檗碱、复配生物碱及6.72 9·kg-1、1.68 g·kg-1、0.849·kg-1剂量的小檗皮浸膏对正常小鼠血糖无明显作用.结论:藏药小檗皮对四氧嘧啶所致糖尿病模型小鼠血糖有明显降糖作用,对正常小鼠血糖无明显作用.     

蒲桃仁提取物降血糖作用的实验研究

采用四氧嘧啶糖尿病小鼠模型及肾上腺素和葡萄糖引起的高血糖小鼠模型,观察蒲桃仁乙醇提取物对实验动物的降血糖效果。蒲桃仁乙醇提取物对四氧嘧啶所致糖尿病小鼠模型、肾上腺素和葡萄糖引起的高血糖模型小鼠有明显的降血糖作用,但对正常小鼠血糖无明显影响。     

沙棘籽渣水提物对正常和糖尿病小鼠血糖的影响

本文研究了沙棘籽渣水提物(Aqueous extract of seabuckthorn seed residues,ASSR)对正常及糖尿病小鼠血糖、血脂代谢的影响。首先采用ASSR灌胃昆明种小鼠的急性毒性试验评价了ASSR的安全性;继而以250mg/kg和500 mg/kg剂量的ASSR连续灌胃正常小鼠3周;以250、500和800 mg/kg剂量的ASSR连续灌胃Al-loxan诱导的糖尿病小鼠3周,监测血糖,测定体重、血清胰岛素、总胆固醇和甘油三酯水平。结果显示:ASSR的LD50大于9.8 g/kg体重;连续给药3周,ASSR对正常小鼠的血糖和血脂代谢没有明显影响,但能明显降低糖尿病小鼠的血清葡萄糖和甘油三酯水平。上述结果表明:ASSR的LD50大于5 g/kg体重,按WHO急性毒性分级标准属于实际无毒级,其在实验性1型糖尿病小鼠模型上具有降血糖和降甘油三酯活性。     

银合欢叶提取物降血糖作用的实验研究

采用四氧嘧啶糖尿病小鼠模型及肾上腺素和葡萄糖引起的高血糖小鼠模型,观察银合欢叶提取物对实验动物的降血糖效果。银合欢叶提取物对四氧嘧啶所致糖尿病小鼠有明显的治疗效果,对肾上腺素和葡萄糖引起的高血糖模型小鼠有明显的降血糖作用,但对正常小鼠血糖无明显影响。     

沙棘籽渣多糖对正常及糖尿病模型动物血糖的影响

本文研究了沙棘籽渣多糖(Polysaccharides from seed residue of Hippophae rhamnoide L.,PSH)对正常小鼠及实验性2型糖尿病大鼠血糖、血脂代谢的影响.以100、200和400 mg/kg剂量的PSH连续灌胃正常小鼠20d;以50和100 mg/kg剂量的PSH连续灌胃由烟酰胺联合链脲佐菌素诱导的类似2型糖尿病大鼠3周,测定血糖、糖基化血清蛋白、血清胰岛素、血清总胆固醇、甘油三酯及肝糖原含量.结果显示:PSH对正常小鼠的血糖和血脂代谢没有明显影响;但能明显降低2型糖尿病大鼠的血清葡萄糖、总胆固醇和糖基化血清蛋白水平,同时显著增加糖尿病大鼠的血清胰岛素含量.上述结果表明:PSH在实验性2型糖尿病大鼠模型上具有降血糖和降胆固醇的活性.     

桦褐孔菌与松口蘑菌粉降血糖作用的研究

为评价桦褐孔菌和松口蘑发酵菌粉的降血糖作用,本文观察了经不同浓度桦褐孔菌和松口蘑菌粉溶液灌胃后,小鼠正常血糖、给予葡萄糖小鼠以及四氧嘧啶糖尿病小鼠血糖的变化.结果表明:桦褐孔菌、松口蘑菌粉溶液(500、1000 mg/kg)对小鼠正常血糖值、正常小鼠糖耐量没有明显影响(P>0.05);对于糖尿病小鼠血糖,桦褐孔菌低剂量组(500 mg/kg)和桦褐孔菌高剂量组(1000 mg/kg)的降糖效果较为明显(P<0.01),用药前与用药后第21 d的血糖值分别为(14.94±1.85)、(10.43±2.22)和(14.89±1.65)、(10.17±2.14) mmol/L,降糖率分别为30.23% 和31.7%.桦褐孔菌和松口蘑菌粉对于小鼠正常血糖、正常小鼠糖耐量无明显影响,对于四氧嘧啶糖尿病小鼠具有一定的降血糖效果.     

野生地参多糖对四氧嘧啶致糖尿病小鼠血糖和血脂的影响

为了研究野生地参多糖对四氧嘧啶(ALX)致糖尿病小鼠血糖和血脂的影响,利用四氧嘧啶(ALX)建立糖尿病小鼠模型,分别灌胃低(100 mg/(kg.d))、中(200 mg/(kg.d))、高(400 mg/(kg.d))剂量地参多糖溶液及阳性对照药盐酸苯乙双胍,正常对照组及糖尿病模型对照组则给等体积生理盐水。结果表明:连续给药14 d后,地参多糖对正常小鼠血糖无明显影响,100、200和400 mg/(kg.d)地参多糖均能明显降低ALX所致糖尿病小鼠高血糖,与糖尿病模型对照组相比,P<0.01;同时,相同剂量的地参多糖还能极显著降低ALX致糖尿病小鼠血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)(P<0.01)。中、高剂量地参多糖使糖尿病小鼠血清高密度脂蛋白胆固醇(HDL-C)显著回升(P<0.05),但低剂量地参多糖对糖尿病小鼠血清HDL-C则无明显影响(P>0.05)。地参多糖能明显降低ALX致糖尿病小鼠高血糖及高血脂。     

胰岛素小鼠皮下注射的降血糖作用研究

目的:了解胰岛素皮下注射后不同时间对小鼠血糖的影响。方法:采用正规胰岛素制剂0.5U/ml予小鼠按0.054ml/10g皮下注射后,观察在注射后30分钟、60分钟、90分钟、120分钟和150分钟后血糖的变化,并在注射150分钟后予10%葡萄糖灌胃,观察小鼠30分钟和60分钟后的血糖变化。结果:皮下注射各剂量的胰岛素均能引起小鼠血糖降低,其中以注射90分钟后血糖下降最为明显,高剂量胰岛素降血糖作用最明显。给予葡萄糖水灌胃后血糖有所升高,但是高剂量恢复比较慢。结论:0.5U/ml胰岛素按0.108ml/10g皮下注射会引起小鼠血糖过低,不利于实验数据的收集,0.027ml/10g和0.054ml/10g剂量比较合适。     

虾青素对四氧嘧啶致糖尿病小鼠降血糖作用研究

为研究天然虾青素在四氧嘧啶致糖尿病小鼠体内的降血糖作用，将天然虾青素分为高、中、低3个剂量组给四氧嘧啶致糖尿病小鼠灌胃，以0．9％生理盐水为模型对照，以二甲双胍为阳性药物对照进行实验。结果表明：三个剂量的天然虾青素均能较好的降低四氧嘧啶致糖尿病小鼠的血糖水平，并能减缓糖尿病小鼠消瘦和多饮多食的症状，以高剂量组的效果最佳。进一步考察了高剂量的虾青素对正常小鼠的影响，发现其对正常小鼠血糖无显著影响。虾青素对四氧嘧啶致糖尿病小鼠具有明显的降血糖作用。     

TNFα对正常昆明小鼠骨骼肌和肝脏葡萄糖摄取的影响

目的观察肿瘤坏死因子α(TNFα)对正常昆明小鼠骨骼肌和肝脏葡萄糖摄取的影响。方法80只昆明小鼠随机分为高剂量连续注射组(TH组,n=20)、TNFα低剂量连续注射组(TL组,n=20)、TNFα高剂量一次注射组(T1组,n=20)和正常对照组(C组,n=20),以3H标记的2脱氧葡萄糖(2-DG)为示踪剂,观察各组非胰岛素刺激(基础)和胰岛素刺激的离体骨骼肌和肝脏葡萄糖摄取量的变化。结果1)正常昆明小鼠肝脏基础葡萄糖摄取量明显高于骨骼肌葡萄糖摄取量(P<0.01),肝脏胰岛素刺激的葡萄糖摄取量变化值明显低于骨骼肌葡萄糖摄取量变化值(P<0.01)。2)TH组和TL组骨骼肌和肝脏基础葡萄糖摄取量均明显高于C组(P<0.01),且TH组明显高于TL组(P<0.01)。3)TH组和TL组骨骼肌和肝脏胰岛素刺激的葡萄糖摄取量均明显低于C组(P<0.01),且TH组明显低于TL组(P<0.01)。4)T1组骨骼肌和肝脏无论基础还是胰岛素刺激的葡萄糖摄取量均与C组差异无显著性(P>0.05)。结论1)正常动物肝脏和骨骼肌葡萄糖摄取方式不同,骨骼肌葡萄糖摄取受胰岛素调控比肝脏强。2)TNFα抑制组织胰岛素刺激的葡萄糖摄取,但促进组织基础葡萄糖摄取。3)TNFα对组织葡萄糖摄取的影响,呈剂量和时间依赖性。     

The involvement of insulin in tryptamine-induced hypoglycemia in mice

The effects of tryptamine on plasma glucose and serum insulin levels were studied in mice. Tryptamine elicited dose-dependent hypoglycemia and hyperinsulinemia in intact mice. In streptozotocin-diabetic mice, tryptamine did not change plasma glucose nor serum insulin levels. Tryptamine significantly inhibited glucose-induced hyperglycemia and enhanced insulin release elicited by glucose. These results indicate that tryptamine-induced hypoglycemia is brought on by its releasing effects of insulin.     

Leptin-induced changes in body composition in high fat-fed mice

Female C57BL/6J mice were adapted to 10% or 45% kcal fat diets for 8 weeks. Continuous intraperitoneal infusion of 10 micro g of leptin/day from a miniosmotic pump transiently inhibited food intake in low fat-fed but not high fat-fed mice. In contrast, both low and high fat-fed leptin-infused mice were less fat than their phosphate-buffered saline (PBS) controls after 13 days. Leptin infusion inhibited insulin release but did not change glucose clearance in low fat-fed mice during a glucose tolerance test. A single intraperitoneal injection of 30 micro g of leptin inhibited 24-hr energy intake and inhibited weight gain in both low and high fat-fed mice. Insulin responsiveness was improved in high fat-fed mice during an insulin sensitivity test due to an exaggerated elevation of circulating insulin concentrations. Thus, leptin infusion reduced adiposity independently of energy intake in high fat-fed mice and improved insulin sensitivity in low fat-fed mice, whereas leptin injections, which produced much greater, but transient, increases in serum leptin concentration, inhibited energy intake in both low and high fat-fed mice.     

Targeted deletion of Tssk1 and 2 causes male infertility due to haploinsufficiency

Targeted deletion of Tssk1 and 2 resulted in male chimeras which produced sperm/spermatogenic cells bearing the mutant allele, however this allele was never transmitted to offspring, indicating infertility due to haploinsufficiency. Morphological defects in chimeras included failure to form elongated spermatids, apoptosis of spermatocytes and spermatids, and the appearance of numerous round cells in the epididymal lumen. Characterization of TSSK2 and its interactions with the substrate, TSKS, were further investigated in human and mouse. The presence of both kinase and substrate in the testis was confirmed, while persistence of both proteins in spermatozoa was revealed for the first time. In vivo binding interactions between TSSK2 and TSKS were established through co-immunoprecipitation of TSSK2/TSKS complexes from both human sperm and mouse testis extracts. A role for the human TSKS N-terminus in enzyme binding was defined by deletion mapping. TSKS immunoprecipitated from both mouse testis and human sperm extracts was actively phosphorylated. Ser281 was identified as a phosphorylation site in mouse TSKS. These results confirm both TSSK 2 and TSKS persist in sperm, define the critical role of TSKS' N-terminus in enzyme interaction, identify Ser 281 as a TSKS phosphorylation site and indicate an indispensable role for TSSK 1 and 2 in spermiogenesis.     

TSKS concentrates in spermatid centrioles during flagellogenesis

Centrosomal coiled-coil proteins paired with kinases play critical roles in centrosomal functions within somatic cells, however knowledge regarding gamete centriolar proteins is limited. In this study, the substrate of TSSK1 and 2, TSKS, was localized during spermiogenesis to the centrioles of post-meiotic spermatids, where it reached its greatest concentration during the period of flagellogenesis. This centriolar localization persisted in ejaculated human spermatozoa, while centriolar TSKS diminished in mouse sperm, where centrioles are known to undergo complete degeneration. In addition to the centriolar localization during flagellogenesis, mouse TSKS and the TSSK2 kinase localized in the tail and acrosomal regions of mouse epididymal sperm, while TSSK2 was found in the equatorial segment, neck and the midpiece of human spermatozoa. TSSK2/TSKS is the first kinase/substrate pair localized to the centrioles of spermatids and spermatozoa. Coupled with the infertility due to haploinsufficiency noted in chimeric mice with deletion of Tssk1 and 2 (companion paper) this centriolar kinase/substrate pair is predicted to play an indispensable role during spermiogenesis.     

Insulin sensitizing and alpha-glucoamylase inhibitory action of sennosides, rheins and rhaponticin in Rhei Rhizoma

Extracts from Rhei Rhizoma extracts (RR) have been reported to attenuate metabolic disorders such as diabetic nephropathy, hypercholesterolemia and platelet aggregation. With this study we investigated the anti-diabetic action of 70% ethanol RR extract in streptozotocin-induced diabetic mice, and determined the action mechanism of active compounds of RR in vitro. In the diabetic mice, serum glucose levels at fasting and post-prandial states and glucose area under the curve at modified oral glucose tolerance tests were lowered without altering serum insulin levels, indicating that RR contained potential anti-diabetic agents. The fractions fractionated from RR extracts by XAD-4 column revealed that 60%, 80% and 100% methanol fractions enhanced insulin sensitivity and inhibited alpha-glucoamylase activity. The major compounds of these fractions were sennosides, rhein and rhaponticin. Rhaponticin and rhein enhanced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Rhaponticin increased adipocytes with a differentiating effect similar to pioglitazone, but rhein and sennoside B decreased triglyceride accumulation. Sennoside A and B inhibited alpha-glucoamylase activity as much as acarbose. In conclusion, a crude extract of RR improves glucose intolerance by enhancing insulin-stimulated glucose uptake and decreasing carbohydrate digestion via inhibiting alpha-glucoamylase activity. Rhein and rhaponticin are potential candidates for hypoglycemic agents.     

Antitumor pathway of Rhizoma Paridis Saponins based on the metabolic regulatory network alterations in H22 hepatocarcinoma mice

Rhizoma Paridis Saponins (RPS), which is the effective part of Rhizoma Paridis, showed strong anti-lung cancer and anti-hepatocarcinoma activities. In this research, a gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the metabolic profiling of RPS intervention in H22 hepatocarcinoma mice. Data were analyzed with partial least-squares discrimination analysis (PLS-DA). As a result, RPS displayed different pathway to decrease energy production of the mice. For the normal mice, RPS significantly decreased the concentration of lipid, glycerate, succinate and lactate, but increased glucose and valine levels. All these indicated that RPS inhibited glucose and valine to transform ketones which participated in the ATP production. For the H22 cancer mice, RPS increased the concentration of lipid and glycerate, but significantly decreased glucose, glycine and alanine levels in the serum. This phenomenon indicated that RPS inhibited the oxidation of fatty acids pathway and the gluconeogenesis pathway which participated in the energy supply for the body. RPS also inhibited glycine and alanine production to block the tumor growth. This selective effect of RPS to different condition of mice would improve understanding of the antitumor pathway of RPS involved in H22 hepatocarcinoma mice.     

Effects of the HIV Protease Inhibitor Ritonavir on GLUT4 Knock-out Mice

HIV protease inhibitors acutely block glucose transporters (GLUTs) in vitro, and this may contribute to altered glucose homeostasis in vivo. However, several GLUT-independent mechanisms have been postulated. To determine the contribution of GLUT blockade to protease inhibitor-mediated glucose dysregulation, the effects of ritonavir were investigated in mice lacking the insulin-sensitive glucose transporter GLUT4 (G4KO). G4KO and control C57BL/6J mice were administered ritonavir or vehicle at the start of an intraperitoneal glucose tolerance test and during hyperinsulinemic-euglycemic clamps. G4KO mice exhibited elevated fasting blood glucose compared with C57BL/6J mice. Ritonavir impaired glucose tolerance in control mice but did not exacerbate glucose intolerance in G4KO mice. Similarly, ritonavir reduced peripheral insulin sensitivity in control mice but not in G4KO mice. Serum insulin levels were reduced in vivo in ritonavir-treated mice. Ritonavir reduced serum leptin levels in C57BL/6J mice but had no effect on serum adiponectin. No change in these adipokines was observed following ritonavir treatment of G4KO mice. These data confirm that a primary effect of ritonavir on peripheral glucose disposal is mediated through direct inhibition of GLUT4 activity in vivo. The ability of GLUT4 blockade to contribute to derangements in the other molecular pathways that influence insulin sensitivity remains to be determined.     

Serotonin-induced hypoglycemia and increased serum insulin levels in mice

The effects of serotonin (5-HT) on plasma glucose levels were studied. 5-HT above 20 mg/kg induced apparent hypoglycemia in mice. The hypoglycemic effects of 5-HT were strongly antagonized by methysergide but only partially inhibited by ketanserin. However, ICS 205-930 was without effect. This indicates that the hypoglycemia induced by 5-HT is mediated by both the 5-HT1 and 5-HT2 receptors. 5-HT also produced an increase in serum immunoreactive insulin (IRI) which was completely inhibited by methysergide and partially antagonized by ketanserin. It is suggested that the 5-HT-induced increase in IRI is elicited by the activation of the 5-HT1 and 5-HT2 receptors, which is similar to the results obtained with plasma glucose. These results indicate that the 5-HT receptors may regulate blood glucose levels by modifying the release of insulin.     

A minor role for lipocalin 2 in high-fat diet-induced glucose intolerance

Adipose tissue controls energy homeostasis and systemic insulin sensitivity through the elaboration of a series of cytokines and hormones, collectively termed "adipokines." We and others have identified Lcn2 as a novel adipokine, but its exact role in obesity-induced insulin resistance remains controversial. The aim of this study was to examine the metabolic phenotype of Lcn2(-/-) mice to clarify the role of Lcn2 in metabolism. Male and female Lcn2(-/-) and wild-type (WT) littermates were placed on either chow or high-fat diet (HFD) to characterize their metabolic phenotype. Studies included body weight and body composition, glucose and insulin tolerance tests, and adipokine expression studies in serum and in white adipose tissue (WAT). Neither chow nor HFD cohorts showed any differences in body weight or body composition. Chow-fed Lcn2(-/-) mice did not exhibit any difference in glucose homeostasis compared with WT mice. Fasting serum glucose levels were lower in the chow-fed Lcn2(-/-) mice, but this finding was not seen in the HFD cohort. Serum adiponectin, leptin, resistin, and RBP4 levels were not different between WT and Lcn2(-/-) on chow diet. HFD-fed male Lcn2(-/-) mice did display a small improvement in glucose tolerance, but no difference in insulin sensitivity was seen in either male or female Lcn2(-/-) mice on HFD. We conclude that the global ablation of Lcn2 has a minimal effect on obesity-associated glucose intolerance but does not appear to affect either age- or obesity-mediated insulin resistance in vivo.