Reduced glucose tolerance and insulin sensitivity after prolonged exercise in endurance athletes

Aim

The purpose of this study was to 1. investigate if glucose tolerance is affected after one acute bout of different types of exercise; 2. assess if potential differences between two exercise paradigms are related to changes in mitochondrial function; and 3. determine if endurance athletes differ from nonendurance-trained controls in their metabolic responses to the exercise paradigms.

Methods

Nine endurance athletes (END) and eight healthy nonendurance-trained controls (CON) were studied. Oral glucose tolerance tests (OGTT) and mitochondrial function were assessed on three occasions: in the morning, 14 h after an overnight fast without prior exercise (RE), as well as after 3 h of prolonged continuous exercise at 65% of VO₂max (PE) or 5 × 4 min at ~95% of VO₂max (HIIT) on a cycle ergometer.

Results

Glucose tolerance was markedly reduced in END after PE compared with RE. END also exhibited elevated fasting serum FFA and ketones levels, reduced insulin sensitivity and glucose oxidation, and increased fat oxidation during the OGTT. CON showed insignificant changes in glucose tolerance and the aforementioned measurements compared with RE. HIIT did not alter glucose tolerance in either group. Neither PE nor HIIT affected mitochondrial function in either group. END also exhibited increased activity of 3-hydroxyacyl-CoA dehydrogenase activity in muscle extracts vs. CON.

Conclusion

Prolonged exercise reduces glucose tolerance and increases insulin resistance in endurance athletes the following day. These findings are associated with an increased lipid load, a high capacity to oxidize lipids, and increased fat oxidation.     

Plasma insulin concentration in the femoral,hepatic, and pancreatico-duodenal veins in dogs during standard and cortisone glucose tolerance tests

Comparison of glucose tolerance tests carried out with or without cortisone showed the advantage of the former when testing the internal secretory function of the pancreas. With the aid of this test the insulin secretion during glucose loading was found to be biphasic. The dynamics of the blood insulin level in the pancreatico-duodenal vein reflects insulin secretion by the pancreas better than the dynamics of its concentration in the blood of the peripheral veins.Laboratory of Pathological Physiology, Institute of Experimental Endocrinology and Hermone Chemistry, Academy of Medical Sciences of the USSR. Department of Operative Surgery and Topographical Anatomy, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 681–684, June, 1976.     

The reproducibility of the oral glucose tolerance test over long (5 years) and short periods (1 week)

Summary Three oral glucose tolerance tests (oGTT) have been performed in 312 non-diabetic relatives of diabetics over a period of 10 years. In a second study 6 identical oGTT's have been performed at weekly intervals in 55 individuals. In this study the variance, calculated from the logarithmic values, increased in the following order: fasting (0.026), 1 h (0.035), 2 h (0.044) and 3 h values (0.047). The sum of the 1 h and 2 h values showed the lowest variance (0.024). No significant difference of the variances was found in the 43 individuals in whom both the long-term and the short-term studies have been performed. Thus, a great proportion of the total variance of glucose observed over longer periods only represents a random variation. This random variation is much higher than most other factors which might influence the result of an oGTT. A diagnosis based on a single oGTT is of only limited value.Supported by a grant from Deutsche Forschungsgemeinschaft (Ko 457/8)     

Impaired glucose tolerance plus hyperlipidaemia induced by diet promotes retina microaneurysms in New Zealand rabbits

With the increasing prevalence of diabetes mellitus and metabolic syndrome worldwide, experimental models are required to better understand the pathophysiology and therapeutic approaches to preserve pancreatic beta cells, attenuate atherosclerosis and protect target organs. The aims of this study were to develop an experimental model of impaired glucose tolerance combined with hypercholesterolaemia induced by diet and assess metabolic alterations and target organ lesions. New Zealand male rabbits were fed high-fat/high-sucrose (10/40%) and cholesterol-enriched diet for 24 weeks, when they were sacrificed. Biochemistry, fundus photographs with fluorescein angiography and pathological analyses were performed. Cholesterol-fed and normal animals of same age were compared. Results: The animals with diet-induced impaired glucose tolerance combined with hypercholesterolaemia gained weight, increased blood glucose, total cholesterol, LDL-C and triglycerides and decreased HDL-C (P < 0.05 vs. baseline). Fructosamine levels and the homeostasis model assessment of insulin resistance (HOMA-IR) index were increased, while there was a reduction in the HOMA-β (P < 0.05 for all vs. baseline). Histomorphologic findings of this model were aortic atherosclerosis, hepatic steatofibrosis and glomerular macrophage infiltration. Early clinical features of diabetic retinopathy with hyperfluorescent dots consistent with presence of retina microaneurysms were seen since week 12, progressing up to the end of the experiment (P < 0.0005 vs. baseline and 12 weeks). Our model reproduced several metabolic characteristics of human diabetes mellitus and promoted early signs of retinopathy. This non-expensive model is suitable for studying mechanistic pathways and allowing novel strategic approaches.     

妊娠期糖代谢异常性巨大儿与葡萄糖耐量试验结果相关分析

目的回顾性研究妊娠期糖代谢异常性巨大儿与非巨大儿孕产妇,分析妊娠期糖代谢异常孕妇口服葡萄糖耐量试验的特点,探讨OGTT各时点血糖检测,在预测妊娠期糖代谢异常性巨大儿发生的诊断价值。方法回顾性收集、分析我院2007年1月～2009年4月146例GDM和GIGT孕妇,将其分为巨大儿组和非巨大儿组研究两组OGTT血糖的特点,以及各点血糖在糖代谢异常性巨大儿中的价值。结果巨大儿组与非巨大儿组GCT差异无统计学意义,两组空腹血糖值、OGTT 1h血糖值差异有统计学意义,OGTT 2h、OGTT 3h血糖值差异无统计学意义。根据ADA诊断标准重新分组,发现去除OGTT 3h血糖各组发生巨大儿差异无统计学意义。结论 1.妊娠期糖代谢异常性巨大儿的发生与确诊GDM及GIGT时空腹血糖及OGTT 1h血糖有关。2.根据ADA诊断标准并在进行OGTT时省略3h血糖的检测可行。     

Bromocriptine treatment over 12 years in acromegaly: effect on glucose tolerance and insulin secretion

Summary It is not known whether the beneficial effect of bromocriptine on glucose homeostasis in acromegaly is limited by a certain duration of therapy. To elucidate this problem, oral glucose tolerance tests were performed in 12 acromegaly patients before bromocriptine medication, under therapy (15.0 ± 6.8 mg/day for 12 ± 3 years), and during a 2-week drug withdrawal after long-term treatment. Initially altered glucose tolerance was normalized in 4 of 5 patients under bromocriptine therapy. During drug withdrawal the mean fasting glucose level and the mean glucose concentration at 120 min after oral glucose load increased from 5.05 ± 0.61 to 5.77 ± 0.78 mmol/1 and from 5.61 ±2.05 to 7.55 ± 3.05 mmol/1, respectively. A deterioration in glucose homeostasis was observed in 9 patients, and impaired glucose tolerance was ameliorated (but not to normal range) in 2 when bromocriptine was withdrawn. The proportion of alterations in glucose tolerance during drug withdrawal corresponded to that before the beginning of long-term bromocriptine treatment. Impaired glucose tolerance, observed in 2 patients under bromocriptine treatment, seemed to be compensated because a distinct elevation of glycosylated hemoglobin A_1c was not observed. Bromocriptine led to a significant decrease in basal as well as glucose-stimulated insulin levels, and growth hormone secretion during oral glucose load was reduced in all 12 patients. Similarly to the increased growth hormone secretion after drug withdrawal in 11 patients, a rise in glucose-stimulated insulin secretion was found in all patients; hereby, the mean insulin levels at 0 and 120 min during oral glucose load rose significantly from 7.5 ± 2.6 to 12.1 ± 5.1 mU/1 (P<0.01) and from 71.3±52.1 to 101.4±50.7 mU/1 (P<0.02), respectively. A direct relationship between disturbance in glucose homeostasis and degree of hypersomatotropism was not observed. Our data confirm that the beneficial effect of bromocriptine therapy on glucose homeostasis in selected patients with acromegaly is still present after dopaminergic treatment over a mean period of 12 years. Compared with the published rates on improved glucose homeostasis under octreotide, the effect of bromocriptine seems to be more favorable.Abbreviations AUC area under the curve - GH growth hormone - PRL prolactin Dedicated to Prof. Dr. N. Zöllner on the occasion of his 70th birthday     

Glucose tolerance and insulin sensitivity of rats poisoned with Amanita phalloides

The effect ofAmanita phalloides toxins on glucose tolerance and insulin sensitivity was studied.Amanita toxins were injected intraperitoneally in a dose of LD₅₀ into male albino rats. Amanita toxins were found to disturb glucose tolerance, to increase the utilization of glucose by the tissues, and to make the animals more sensitive to insulin. These effects may be the result of depression of the insulin-activating capacity of the liver and potentiation of the function of the islet-cell apparatus of the pancreas.Department of General Biology, Ternopol' Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR S. N. Golikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 9, pp. 319–321, September, 1978.     

The effect of sleep continuity disruption on multimodal emotion processing and regulation: a laboratory-based,randomised, controlled experiment in good sleepers

Previous research shows that experimental sleep deprivation alters emotion processing, suggesting a potential mechanism linking sleep disruption to mental ill-health. Extending previous work, we experimentally disrupted sleep continuity in good sleepers and assessed next-day emotion processing and regulation using tasks with established sensitivity to depression. In a laboratory-based study, 51 good sleepers (37 female; mean [SD] age 24 [3.63] years), were randomised to 1 night of uninterrupted sleep (n = 24) or sleep continuity disruption (n = 27). We assessed emotion perception, attention, and memory the following day. Participants also completed an emotion regulation task and measures of self-reported affect, anxiety, sleepiness, overnight declarative memory consolidation, and psychomotor vigilance. Confirming the effects of the manipulation, sleep continuity disruption led to a marked decrease in polysomnography-defined total sleep time (229.98 versus 434.57 min), increased wake-time after sleep onset (260.66 versus 23.84 min), and increased sleepiness (d = 0.81). Sleep continuity disruption led to increased anxiety (d = 0.68), decreased positive affect (d = −0.62), reduced overnight declarative memory consolidation (d = −1.08), and reduced psychomotor vigilance (longer reaction times [d = 0.64] and more lapses [d = 0.74]), relative to control. However, contrary to our hypotheses, experimental sleep disruption had no effect on perception of, or bias for, emotional facial expressions, emotional memory for words, or emotion regulation following worry induction. In conclusion, 1 night of sleep continuity disruption had no appreciable effect on objective measures of emotion processing or emotion regulation in response to worry induction, despite clear effects on memory consolidation, vigilance, and self-reported affect and anxiety.     

Altered sleep duration and sleep period time displacements: Effects on performance in habitual long sleepers

Performance was studied in 10 healthy young adult males who characteristically sleep 9 $\text{1}\text{2}$ – 10 $\text{1}\text{2}$ hr following an electroencephalographically (EEG) recorded habitual sleep night and 4 nights on which their customary sleep was altered by 3 hr as follows: extended (E), deprived (D), delayed shift (DS), and advanced shift (AS). In the E condition sleep was extended by advancing sleep onset 3 hr corresponding to the AS condition which had the same retiring time, but differing from it with awakening occurring 3 hr earlier. In the D and DS conditions time of sleep onset was delayed 3 hr and the subjects were awakened at their customary time in the D condition, but 3 hr later than usual in the DS condition. Subjects performed an auditory vigilance task 35 min after awakening, at midday and in the early evening. Throughout the day after both shifted sleep and altered sleep duration performance was significantly impaired to an equivalent degree as reflected by longer reaction time, increased misses and a decline of intrinsic perceptual capacity. Changes in the vigilance measures did not correlate with sleep duration or any other specific alterations in the EEG patterns of sleep. The behavioral deficits which resulted from altered sleep schedules are discussed viewing sleep as a biological adaptive process with respect to the feature of its occurrence under natural conditions in a temporally rhythmic sequence.     

Plasma levels of oxytocin after food deprivation and hypoglycaemia,and effects of 1–deamino-2–D-Tyr—(OEt)-4–Thr-8–Orn-oxytocin on blood glucose in rats

Björkstrand , E., Eriksson , M. & Uvnäs -Moberg , K. 1992. Plasma levels of oxytocin after food deprivation and hypoglycaemia, and effects of l-deamino-2–D-Tyr-(OEt)-l-Thr-8–Om-oxytocin on blood glucose in rats. Acta Physiol Scand 144 , 355–359. Received 1 March 1 991 , accepted 25 October 1991. ISSN 0001–6772. Department of Pharmacology, Karolinska Institute, Sweden. Oxytocin has been shown to influence insulin, glucagon and blood glucose levels in various experimental situations. The present study was performed in order to obtain support for a possible interaction of glucose and oxytocin under physiological conditions. We therefore studied whether or not short-term food deprivation (24 hours) affects basal oxytocin levels in male, female and lactating rats, since this is a situation when glucose is mobilized to prevent hypoglycaemia. Secondly, we studied whether oxytocin levels rise in a situation when blood glucose levels fall, i.e. following i.p. injection of insulin (20 U kg^-1). In order to explore the role of oxytocin more directly, we investigated whether i.p. injection of the oxytocin antagonist 1–deamino-2–D-Tyr-(OEt)-4–Thr-8–Orn-oxytocin affects blood glucose levels. Plasma levels of oxytocin, insulin and glucagon were measured with radioimmunoassay in samples obtained after decapitation. We found that oxytocin levels were significantly increased following short-term food deprivation in lactating rats. We also found that insulin-induced hypoglycaemia could elevate plasma levels of oxytocin in female and male rats. In addition, administration of an oxytocin antagonist cause a small, hut significant decrease in blood glucose levels after 30 min. These data imply that oxytocin may he one of several factors that take part in the control of blood glucose regulation.     

乙胺嘧啶对二硝基氟苯所致小鼠接触超敏性和耐受性的影响

实验采用了小鼠由细胞介导的免疫反应——二硝基氟苯(DNFB)所致接触超敏性和耐受性的动物摸型,以耳肿(Ear swelling)作为测量指标,观察了乙胺嘧啶对DNFB所致C_(57)小鼠接触超敏性和耐受性的影响。实验表明,乙胺嘧啶对适宜剂量DNFB致敏造成的接触超敏反应无影响。但乙胺嘧啶在致敏当天腹腔注射给予,能逆转由于大剂量DNFB致敏造成的免疫抑制,但其逆转程度不超过适宜剂量DNFB致敏造成最强免疫反应程度。在致敏当天给予乙胺嘧啶也能逆转由于静注DNFB耐受原造成的免疫耐受。结果提示,乙胺嘧啶逆转受抑免疫反应的作用不应称为“免疫增强”作用,拟称为“免疫逆转”作用为妥。乙胺嘧啶逆转受抑免疫反应和免疫耐受的机理可能是对抗原激活的抑制性T细胞(Ts)有选择性的抑制作用。乙胺嘧啶有可能作为免疫调节剂在科研和临床上加以应用。本文对C_(57)小鼠的接触超敏性和耐受性进行探讨,摸索了适宜致敏剂量和致耐剂量,并对动物摸型的作用和机理进行了讨论。     

糖耐量减低的绝经后女性血浆和肽素水平与血糖的相关性

目的:观察糖耐量减低的绝经后女性血浆和肽素水平与血糖的相关性.方法:将80例新发糖耐量减低(空腹血糖≤6.2 mmol/L,7.8 mmol/L≤甲餐后2h血糖≤9.4 mmol/L)的绝经后女性,年龄56～59岁,依据基线时和肽素水平,分成A组(＜5 pmol/L)、B组(＞20 pmol/L组),每组各40例.分析两组间基线时和6个月后和肽素、血糖的差异.结果:基线时,A组与B组组间的和肽素差异有统计学意义(P＜0.05),而在体重、空腹全血血糖、早餐后2h血糖、空腹血清三酰甘油、血清总胆固醇、血清低密度脂蛋白胆固醇、平均动脉压、血清肌酐水平、年龄等指标上结果相似,差异无统计学意义.经调整生活方式及口服阿司匹林(100 mg/d)、瑞舒伐他汀(10 mg/d)6个月后,在和肽素水平、空腹血糖、早餐后2h血糖指标上,B组明显高于A组,差异有统计学意义(P＜0.05).B组中有新发糖尿病16例,而A组没有.结论:在糖耐量减低的绝经后女性中,高血浆和肽素水平会进一步加重糖耐量减低,促使糖尿病的发生.     

The effect of prior exercise on oral glucose tolerance in late gestational women

Summary Glucose tolerance deteriorates over the course of a normal human pregnancy as a result of increased peripheral insulin resistance. In contrast, physical exercise has been shown to improve glucose tolerance and blunt the insulin response to a glucose load in insulin-resistant individuals. The purpose of this study was to determine the effect of exercise on glucose tolerance and the insulin response in healthy women during the third trimester of pregnancy (33 weeks of gestation). Five subjects underwent oral glucose tolerance tests (a) 30 min following a 30-min exercise bout on a cycle ergometer at a relative intensity of 50% maximal aerobic capacity, and (b) on a control day without prior exercise. The area under the glucose concentration curve was not different between trials, while the area under the insulin concentration curve was decreased by 23% in the exercise trial compared with the control trial (P < 0.05). These results suggest that the insulin response to a glucose load is improved in late gestational women by a single bout of moderate intensity exercise.     

The effect of sleep restriction on cognitive performance in elite cognitive performers: a systematic review

Study ObjectivesTo synthesize original articles exploring the effects of sleep restriction on cognitive performance specifically for Elite Cognitive Performers, i.e. those who engage in cognitively demanding tasks with critical or safety-critical outcomes in their occupation or area of expertise.MethodsBackward snowballing techniques, gray literature searches, and traditional database searches (Embase, MEDLINE, Web of Science, Google Scholar, PSYCinfo, and SportDiscus) were used to obtain relevant articles. A quality assessment was performed, and the risk of training effects was considered. Results were narratively synthesized. Fourteen articles fit the criteria. Cognitive outcomes were divided into three categories defined by whether cognitive demands were “low-salience,” “high-salience stable,” or “high-salience flexible.”ResultsLow-salience tests (i.e. psychomotor vigilance tasks & serial reaction tests), mainly requiring vigilance and rudimentary attentional capacities, were sensitive to sleep restriction, however, this did not necessarily translate to significant performance deficits on low-salience occupation-specific task performance. High-salience cognitive outcomes were typically unaffected unless when cognitive flexibility was required.ConclusionsSleep restriction is of particular concern to occupations whereby individuals perform (1) simple, low-salience tasks or (2) high-salience tasks with demands on the flexible allocation of attention and working memory, with critical or safety-critical outcomes.     

The effects of total sleep deprivation, selective sleep interruption and sleep recovery on pain tolerance thresholds in healthy subjects

The aim of this study was to compare the effects of total sleep deprivation (TSD), rapid eye movement (REM) sleep and slow wave sleep (SWS) interruption and sleep recovery on mechanical and thermal pain sensitivity in healthy adults. Nine healthy male volunteers (age 26--43 years) were randomly assigned in this double blind and crossover study to undergo either REM sleep or SWS interruption. Periods of 6 consecutive laboratory nights separated by at least 2 weeks were designed as follows: N1 Adaptation night; N2 Baseline night; N3 Total sleep deprivation (40 h); N4 and N5 SWS or REM sleep interruption; N6 Recovery. Sleep was recorded and scored using standard methods. Tolerance thresholds to mechanical and thermal pain were assessed using an electronic pressure dolorimeter and a thermode operating on a Peltier principle. Relative to baseline levels, TSD decreased significantly mechanical pain thresholds (-8%). Both REM sleep and SWS interruption tended to decrease mechanical pain thresholds. Recovery sleep, after SWS interruption produced a significant increase in mechanical pain thresholds (+ 15%). Recovery sleep after REM sleep interruption did not significantly increase mechanical pain thresholds. No significant differences in thermal pain thresholds were detected between and within periods. In conclusion this experimental study in healthy adult volunteers has demonstrated an hyperalgesic effect related to 40 h TSD and an analgesic effect related to SWS recovery. The analgesic effect of SWS recovery is apparently greater than the analgesia induced by level I (World Health Organization) analgesic compounds in mechanical pain experiments in healthy volunteers.     

Neuroprotective effect of ultra-low doses of antibodies against S100 protein in neuroblastoma culture during oxygen and glucose deprivation

Antibodies against S100 protein applied in high and ultra-high dilutions possess neuroprotective activity and maintain survival of neuroblastoma C-1300 cells under conditions of oxygen and glucose deprivation. The examined antibody preparations stimulated differentiation in neuroblastoma culture thereby demonstrating pronounced neurotrophic activity. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 9, pp. 260–263, September, 2007     

The effect of time on task,sleep deprivation,and time of day on simulated driving performance

Sleep deprivation and time of day have been shown to play a critical role in decreasing ability to sustain attention, such as when driving long distances. However, a gap in the literature exists regarding external factors, such as workload. One way to examine workload is via modulating time on task. This study investigated the combined effect of sleep deprivation, time of day, and time on task as a workload factor on driving performance. Twenty-one participants (18–34 years, 10 females) underwent 62 h of sleep deprivation within a controlled laboratory environment. Participants received an 8-h baseline and 9.5-h recovery sleep. Every 8 h, participants completed a Psychomotor Vigilance Task (PVT), Karolinska Sleepiness Scale (KSS), 30-min monotonous driving task and NASA-Task Load Index (TLX). Driving variables examined were lane deviation, number of crashes, speed deviation and time outside the safe zone. Workload was measured by comparing two 15-min loops of the driving track. A mixed model ANOVA revealed significant main effects of day and time of day on all driving performance measures (p < .001). There was a significant main effect of workload on lane deviation (p < .05), indicating that a longer time on task resulted in greater lane deviation. A significant main effect of day (p < .001) but not time of day for the NASA-TLX, PVT and KSS was found. Time on task has a significant further impact on driving performance and should be considered alongside sleep deprivation and time of day when implementing strategies for long-distance driving.     

The effect of low and high NaCl diets on oral glucose tolerance

Summary The effects of low and high NaCl diets on plasma glucose and insulin responses to glucose ingestion were investigated in 15 patients with essential hypertension. Oral glucose (75 g) tolerance tests were carried out while patients were taking diets with low (2 g/day) and high (20 g/day) NaCl content. Fasting plasma glucose and insulin levels were both significantly lower during ingestion of the high NaCl diet (p<0.05). After glucose ingestion, the incremental areas under the two hour plasma glucose and insulin curves were significantly smaller during ingestion of the high NaCl diet (glucosep<0.005 and insulinp<0.025). These findings that low NaCl diets increase the glycemic response to glucose loads suggest that use of NaCl restriction for the treatment of essential hypertension may not always be desirable.Abbreviations Na⁺, K⁺-ATPase sodium, potassium adenosinetriphosphatase - SEM standard error of the mean