Hormonal and metabolic response to three types of exercise of equal duration and external work output

Summary Five normal men, aged 20–30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120–180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output _max=600−900 W), continuous cycling at 50 rev · min⁻¹ (II; _max=100−150 W) and seven bouts of intermittent cycling at 70 rev · min⁻¹ (III; _max=300−450 W). Plasma cortisol, glucagon and lactate increased significantly (P<0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest , , _max or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.     

Der Stoffwechsel bei vollständigem Fasten. Unterschiedliches Verhalten bei Männern und Frauen sowie bei Normalpersonen und Adipösen

Zusammenfassung Bei 24 idealgewichtigen und 24 adipösen Personen beiderlei Geschlechts wurden zirkulierende Substrate (Blutzucker, freie Fettsäuren, Ketonkörper) und Hormone (Insulin, Wachstumshormon, Pankreasglukagon) während sechstägigem Fasten bestimmt. Der Blutzucker sank bei Normalpersonen unter Nulldiät auf tiefere Werte als bei Adipösen. Der Konzentrationsanstieg der freien Fettsäuren und Ketonkörper erfolgte bei Normalgewichtigen rascher als bei Fettsüchtigen und bei Frauen rascher als bei Männern. Das Plasmainsulin fiel bei Adipösen stärker ab als bei Normalpersonen. Alle untersuchten Gruppen wiesen nach 1–3 Fastentagen einen signifikanten Anstieg des Pankreasglukagons auf, dieser erfolgte jedoch bei normalgewichtigen Frauen rascher als bei Männern. Wachstumshormon (GH) stieg bei normalgewichtigen Männern unter Nulldiät signifikant an, bei adipösen Männern jedoch nicht. Bei z.T. auffallend hohen Nüchternwerten zeigten normalgewichtige Frauen keinen signifikanten GH-Anstieg, jedoch signifikant höhere GH-Konzentrationen als adipöse Frauen nach 1–6 Fastentagen. Ausgehend von den allen untersuchten Gruppen gemeinsamen Stoffwechselveränderungen bei Nulldiät werden die diesbezüglichen Unterschiede zwischen männlichen und weiblichen sowie zwischen normalgesichtigen und adipösen Personen diskutiert.     

血糖感应型胰岛素给药智能载体的研究进展

胰岛素控制释放高分子载体系统一直是国内外科技工作者的研究热点 ,迄今已经研究报道了多种具有不同工作原理的血糖感应型胰岛素给药智能载体。本文基于国内外大量研究文献 ,综述了血糖感应型胰岛素控制释放智能化高分子载体的研究进展。     

Effect of insulin on sex differences in the intake of glucose solutions in rats

Adult male and female Wistar rats maintained on ad lib diet were given a choice between tap water and a solution of glucose in the concentration of either 5 or 12%. Both sexes exhibited a marked preference for glucose solutions. With the 5% solution the volume intake was similar in both sexes and the total calorie intake was normal. With the 12% solution the volume intake was higher in females than in males, while in both sexes the total calorie intake was increased to a similar (maximum acceptable) level. Treatment with Protamine Zinc Insulin (PZI) in a daily dose of 40 U/kg b.w. markedly increased the intake of the 5% solution in both sexes, but significantly more in females than in males, thus revealing sex differences which were not manifest in untreated rats. PZI treatment had little effect on 12% glucose solution intake, presumably because with this solution the total calorie intake was increased to a maximum already in untreated rats.     

Increase of food intake induced by glucagon in the rat

The effect of intraperitoneal administration of saline, glucose (25 mg/100 g b.w.), insulin (0.025 U/100 g b.w.) and glucagon (50 micrograms/kg b.w.) on glycemia, liver glycogen concentration and food intake was studied on 104 male adult Wistar rats. When saline was injected the amount of food ingested was similar to that expected at the metabolic moment selected for the tests. Glucose administration did not reduce food intake but both insulin and glucagon provoked a threefold increase during the 60 minutes ensuing the injection. The overall ingestion of food during the 24 hours after the injection of the hormones was significantly higher (about 10%) than the control values during the preceding or the succeeding 24 hours. A hyperphagic, rather than a hypophagic effect of glucagon administration is possibly related to the small dose used in the experiments. The mechanisms involved in the increase of food intake due to glucagon are discussed in terms of acceleration of the metabolic reactions that normally prevent large drops of glycemia as glucose utilization proceeds during the inter-meal periods and that in physiological conditions build up until the need for food arises.     

Increase in insulin response to glucose in the rat chronically treated with clonidine

Summary Effect of chronic clonidine treatment on the response to glucose of rat pancreatic B-cells was investigated. Clonidine treatment was carried out for 10 days by dissolving the drug into drinking water at a concentration of 10 g/ml. Control rats were given drug-free tap water. Serum insulin responses to glucose (750 mg/kg, i. v.) of clonidinetreated rats were much smaller than those of control rats. However, after 1 day's withdrawal of clonidine, the rise in the serum insulin level induced by glucose was approximately 2-fold larger in clonidine-treated rats as compared to that in control rats. Since clonidine treatment decreased body weight of the rat by 10%–20% in 10 days, the same experiments were carried out with rats whose body weight loss was made comparable to that of clonidine-treated rats by restricting food for 10 days. Then, some animals of the group thus treated had food-restriction discontinued for 1 day. In both of the above two groups, no increment in glucoseinduced rise in serum insulin level was observed. Islets of Langerhans isolated from clonidine-treated rats showed pronounced insulin releasing capacity in response to glucose. Insulin content per islet of the clonidine-treated rat was slightly larger than that of control rat. These results indicate that the enhancement of serum insulin response to glucose following clonidine treatment is mainly attributable to the hyper-responsiveness developed in the pancreatic B-cells.     

Insulin receptors in lizard brain and liver: structural and functional studies of α and β subunits demonstrate evolutionary conservation

Summary Specific insulin receptors are present in the liver and brain of the lizard Anolis carolinesis. In this study, the specific binding of ¹²⁵I-insulin to the receptors showed time, temperature and pH dependency. Specific binding to crude membranes prepared from brain was 1–2% of the total radioactivity added compared to 4–5% in the crude membranes prepared from liver. Solubilization and wheat germ agglutinin purification of the membranes resulted in an increase in the specific binding (per mg of protein) between 6 and 32 times for liver membranes and 13–186 for brain membranes. Binding inhibition of tracer insulin by unlabeled porcine insulin was characteristic for insulin receptors with 50% inhibition for liver crude membranes at 60 ng/ml of porcine insulin and 0.7 ng/ml for purified brain insulin receptors. Chicken insulin was 2- to 3-fold more potent and proinsulin about 100 times less potent than porcine insulin. The -subunits of liver and brain had apparent molecular weights on sodium dodecyl sulfate polyacrylamide gel electrophoresis of 135 kDa and 120 kDa respectively. Apparent molecular weights of subunits were 92 kDa for both tissues. Insulin stimulated phosphorylation of the subunit of both brain and liver receptors. Both tissues demonstrated tyrosine-specific phosphorylation, which was stimulated by insulin, of exogenously added artificial substrates. In addition, purified brain insulin receptor preparations contained an endogenous protein with apparent molecular weight of 105 kDa, whose phosphorylation was stimulated by insulin (10^–7 mol/l). This phosphoprotein was not immunoprecipitated by anti-insulin receptor antibodies. These studies suggest that the structural differences between brain and liver receptors previously demonstrated in the rat are also present in the lizard, which is about 300,000,000 years older than the mammalian species. Thus, there is strong evolutionary conservation of the brain insulin receptor.     

鹰嘴豆芽素A通过调节TLR4/NF-κB/NLRP3信号通路减轻卵清蛋白诱导哮喘大鼠的气道炎症

[目的] 探讨鹰嘴豆芽素A（BCA）通过调节Toll样受体4（TLR4）/核因子-κB（NF-κB）/NOD样受体蛋白3（NLRP3）信号通路对卵清蛋白（OVA）诱导哮喘大鼠气道炎症的影响。[方法] 将SD大鼠分为对照（CK）组、模型（Model）组、低剂量BCA组（BCA-L组,25 mg/kg）、高剂量BCA组（BCA-H组,100 mg/kg）、地塞米松阳性对照组（Dex组,1 mg/kg）、BCA-H+LPS（TLR4激活剂）组（100 mg/kg+0.1 mg/kg）,每组12只。除CK组,其他组均通过OVA诱导构建哮喘大鼠模型。建模成功24 h后,进行给药处理,给药每日1次,持续10 d。利用动物肺功能测定仪检测大鼠吸气阻力、呼气阻力、肺通气顺应性的变化;吉姆萨（Giemsa）染色检测支气管肺泡灌洗液（BALF）中细胞总数、淋巴细胞数、嗜酸性粒细胞数、中性粒细胞数;酶联免疫吸附剂测定（ELISA）检测BALF中肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）、干扰素-γ（IFN-γ）水平;苏木精-伊红染色法（HE）染色检测大鼠肺组织病理变化;免疫组化检测大鼠肺组织中嗜酸性粒细胞趋化因子（Eotaxin）表达;蛋白质印迹法（Western Blot）检测大鼠肺组织中TLR4、p-NF-κB p65、NLRP3蛋白表达。[结果] 与CK组比较,Model组大鼠吸气阻力、呼气阻力、BALF中细胞总数、淋巴细胞数、嗜酸性粒细胞数、中性粒细胞数、TNF-α、IL-1β、IFN-γ水平升高,肺组织中的支气管及血管周围炎性细胞浸润明显,肺组织中Eotaxin阳性染色面积百分数、TLR4、p-NF-κB p65、NLRP3蛋白表达升高,肺通气顺应性降低（P<0.05）;与Model组比较,BCA-L组、BCA-H组、Dex组对应指标变化趋势与上述相反（P<0.05）;LPS减弱了高剂量BCA对哮喘大鼠气道炎症的改善作用。[结论] BCA可能通过抑制TLR4/NF-κB/NLRP3信号通路减轻OVA诱导哮喘大鼠的气道炎症。     

Effects of a single bout of short-duration high-intensity and long-duration low-intensity exercise on insulin resistance and adiponectin/leptin ratio

ObjectivesModerate-intensity exercise improves insulin sensitivity, which may depend on the intensity, duration, and frequency of exercise. We examined the effects of a single bout of short-duration high-intensity exercise (HIE) and long-duration lowintensity exercise (LIE) on insulin sensitivity and the adiponectin/leptin ratio in individuals with different body mass indices (BMIs) who do not exercise regularly.MethodsWe enrolled 42 healthy volunteers aged 20–64 years and divided them into two groups based on BMI: BMI <24 kg/m² and BMI ≥27 kg/m². They were randomly assigned to either the short-duration (20 min) HIE (70%–80% heart rate reserve, HRR) or long-duration (60 min) LIE training groups (30%–40% HRR). Glucose, insulin, adiponectin, and leptin levels were assessed before training and at 0, 30, 60, and 120 min after training.ResultsWe finally analyzed 27 normal weight and 9 obese individuals. No significant differences were observed in the baseline information of both BMI groups. Homeostatic model assessment for insulin resistance significantly improved for both exercise patterns in the normal weight group and for the HIE pattern in the obese group (P < 0.01), whereas the adiponectin/leptin ratio increased significantly only among normal weight participants with the LIE intervention.ConclusionBoth exercise patterns in BMI <24 kg/m² and BMI ≥27 kg/m² benefit on insulin resistance. Therefore, people can choose the way they can fit to improve insulin resistance both short-duration high-intensity exercise and long-duration low-intensity exercise.