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      Null effect of ginsenoside Rb1 on improving glycemic status in men during a resistance training recovery

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          Abstract

          Background

          Ginsenoside Rb1, a principle active ingredients of Panax ginseng, has been shown to lower blood glucose in animals and increase insulin secretion in cultured insulinoma cells. The aim of this study was to determine the effects of daily ginsenoside Rb1 supplementation on circulating glucose and insulin levels in men during a 5-day recovery period after an acute bout of resistance exercise.

          Methods

          Twelve gymnasts (20.5 ± 0.3 years of age) participated in this double blind placebo-controlled crossover trial. They were challenged by a lower-limb resistance exercise at a weight load of 85 % one-repetition maximal (1-RM) for 10 repetitions, six sets of the movement. Rb1 (1 ng/kg) or Placebo was orally delivered to participants daily during a 5-day recovery period after challenge. Circulating insulin, glucose and heart rate variability (HRV) were measured under fasted condition in the morning at Days 1, Day 3, and Day 5 during recovery.

          Results

          No significant effect of Rb1 on circulating glucose and insulin levels were found among participants during the 5-day recovery period. A persistent elevation in sympathetic nervous activity, indicated by increased HRV-low frequency/high frequency (HRV-LF/HF) power, during the Rb1 trial was observed.

          Conclusions

          The result of the study suggests that the null effect of Rb1 supplementation on lowering glucose and insulin levels of participants may be associated with chronic sympathetic activation.

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          Most cited references22

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          Vagal tone: a physiologic marker of stress vulnerability.

          S Porges (1992)
          Vagal tone is proposed as a novel index of stress vulnerability and reactivity with applications in all branches of medicine, and with particular value in pediatrics. The paper proposes a model emphasizing the role of the parasympathetic nervous system and particularly the vagus nerve in mediating homeostasis and defining stress. Measurement of cardiac vagal tone is proposed as a method to assess on an individual basis both the stress response and the vulnerability to stress. The method monitors the neural control of the heart via the vagus (ie, vagal tone) as an index of homeostasis. The method provides a standard instrument with statistical parameters that are comparable between patients and throughout the life span. This noninvasive method will allow the assessment of the stressful impact of various clinical treatments on the young infant and permit the identification of individuals with vulnerabilities to stress.
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            Antiobesity and Antihyperglycemic Effects of Ginsenoside Rb1 in Rats

            OBJECTIVE Obesity and type 2 diabetes are national and worldwide epidemics. Because currently available antiobesity and antidiabetic drugs have limited efficacy and/or safety concerns, identifying new medicinal agents, such as ginsenoside Rb1 (Rb1) as reported here, offers exciting possibilities for future development of successful antiobesity and antidiabetic therapies. RESEARCH DESIGN AND METHODS Changes in feeding behavior after acute intraperitoneal administration of Rb1 and the effects of intraperitoneal Rb1 for 4 weeks on body weight, energy expenditure, and glucose tolerance in high-fat diet (HFD)-induced obese rats were assessed. We also examined the effects of Rb1 on signaling pathways and neuropeptides in the hypothalamus. RESULTS Acute intraperitoneal Rb1 dose-dependently suppressed food intake without eliciting signs of toxicity. This inhibitory effect on feeding may be mediated by central mechanisms because Rb1 stimulated c-Fos expression in brain areas involved in energy homeostasis. Consistent with this, Rb1 activated the phosphatidylinositol 3-kinase/Akt signaling pathway and inhibited NPY gene expression in the hypothalamus. Four-week administration of Rb1 significantly reduced food intake, body weight gain, and body fat content and increased energy expenditure in HFD-induced obese rats. Rb1 also significantly decreased fasting blood glucose and improved glucose tolerance, and these effects were greater than those observed in pair-fed rats, suggesting that although Rb1's antihyperglycemic effect is partially attributable to reduced food intake and body weight; there may be additional effects of Rb1 on glucose homeostasis. CONCLUSIONS These results identify Rb1 as an antiobesity and antihyperglycemic agent.
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              Reflex sympathetic activation induces acute insulin resistance in the human forearm.

              Inferences about the association between sympathetic overactivity and insulin resistance have been drawn from the infusion of sympathomimetic amines in supraphysiological doses. We used the isolated perfused human forearm to investigate the effect of reflex-induced sympathetic nervous system activation on the peripheral utilization of glucose in the skeletal muscles of 14 healthy men. Local hyperinsulinemia in the forearm (132 +/- 25 microunits/mL for 90 minutes) induced a significant increase in the utilization of glucose from baseline (16.4 +/- 3.1 mg.dL-1.min-1 per 100 mL forearm volume) to a plateau (85.7 +/- 15.1 mg.dL-1.min-1 per 100 mL forearm volume) between 40 and 60 minutes of insulin infusion but did not alter the utilization of oxygen. Reflex sympathetic nervous system activation was elicited by unloading of cardiopulmonary receptors with bilateral thigh cuff inflation to 40 mm Hg between 60 and 90 minutes of insulin infusion. Blood flow in the forearm was significantly decreased with inflation of thigh cuffs (average decrease of 19%, p < 0.0001). As a result of thigh cuff inflation, there was a reduction in the utilization of glucose (a decrease of 23%, p < 0.02), whereas oxygen utilization was unchanged. We find that an increase in sympathetic nervous system activation (within the normal range of physiological responses) can cause acute insulin resistance in the forearm of healthy volunteers. The reflex caused no change in oxygen utilization, but the same stimulus elicited a decrease in the utilization of glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
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                Author and article information

                Contributors
                brad1819@gmail.com
                tsai@ntsu.edu.tw
                cyhuang@mail.cmu.edu.tw
                chsieh@mail.nhcue.edu.tw
                gmrungchai@gmail.com
                fanyu@utaipei.edu.tw
                shinda@mail.cmu.edu.tw
                kuochiahua@gmail.com
                Journal
                J Int Soc Sports Nutr
                J Int Soc Sports Nutr
                Journal of the International Society of Sports Nutrition
                BioMed Central (London )
                1550-2783
                20 August 2015
                20 August 2015
                2015
                : 12
                : 34
                Affiliations
                [ ]Department of Sports Sciences, Laboratory of Exercise Biochemistry, University of Taipei, Taipei, Taiwan
                [ ]Department of Physical Education, National Hsinchu University of Education, Hsinchu, Taiwan
                [ ]Department of Athletic Training and Health, National Taiwan Sport University, Taoyuan, Taiwan
                [ ]Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan
                [ ]College of Sports Science and Technology, Mahidol University, Salaya, Thailand
                [ ]Department of Rehabilitation Science, China Medical University, Taichung, Taiwan
                [ ]Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan
                [ ]Department of Healthcare Administration, Asia University, Taichung, Taiwan
                Article
                95
                10.1186/s12970-015-0095-6
                4545376
                3c2f04a8-003e-42f1-91a2-28ed0b5ab819
                © Chang et al. 2015

                Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

                History
                : 7 October 2014
                : 12 August 2015
                Categories
                Research Article
                Custom metadata
                © The Author(s) 2015

                Sports medicine
                Sports medicine

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