Eight weeks of high-intensity interval training versus stretching do not change the psychoneuroendocrine response to a social stress test in emotionally impulsive humans.

PURPOSE: Research supports physical activity as a method to heighten stress resistance and resilience through positive metabolic alterations mostly affecting the neuroendocrine system. High-intensity interval training (HIIT) has been proposed as a highly effective time-saving method to induce those changes. However, existing literature relies heavily on cross-sectional analyses, with few randomised controlled trials highlighting the necessity for more exercise interventions. Thus, this study aims to investigate the effects of HIIT versus an active control group on the stress response to an acute psychosocial stressor in emotionally impulsive humans (suggested as being strong stress responders). METHODS: The study protocol was registered online (DRKS00016589) before data collection. Sedentary, emotionally impulsive adults (30.69 ± 8.20 y) were recruited for a supervised intervention of 8 weeks and randomly allocated to either a HIIT (n = 25) or a stretching group (n = 19, acting as active controls). Participants were submitted to a test battery, including saliva samples, questionnaires (self-efficacy- and perceived stress-related), visual analogue scales (physical exercise- and stress-related), and resting electroencephalography and electrocardiography assessing their reaction to an acute psychological stressor (Trier Social Stress Test) before and after the exercise intervention. RESULTS: HIIT increased aerobic fitness in all participants, whereas stretching did not. Participants from the HIIT group reported perceiving exercising more intensively than those from the active control group (ƞp2 = 0.108, p = 0.038). No further group differences were detected. Both interventions largely increased levels of joy post-TSST (ƞp2 = 0.209, p = 0.003) whilst decreasing tension (ƞp2 = 0.262, p < 0.001) and worries (ƞp2 = 0.113, p = 0.037). Finally, both interventions largely increased perceived levels of general self-efficacy (ƞp2 = 0.120, p = 0.029). CONCLUSION: This study suggests that 8 weeks of HIIT does not change the psychoneuroendocrine response to an acute psychological stress test compared to an active control group in emotionally impulsive humans. Further replications of supervised exercise studies highly powered with active and passive controls are warranted.

The German Three Factor Impulsivity Index: Confirmatory factor analysis and ties to demographic and health-related variables.

A growing body of research has focused on the differentiation of emotion-related versus non-emotion-related impulsivity, assessed by the Three-Factor Impulsivity (TFI) index. The goal of this study is to develop a German TFI index, and to validate the emotion-related impulsivity subscales against indices of substance abuse, physical or psychological disorder, physical exercise, BMI, and hours of sleep. 395 native-German speakers completed the German TFI index and questions on validity indicators online. Factor analyses supported the three-factor structure, including Pervasive Influence of Feelings, Lack of Follow Through, and Feelings Trigger Action. Correlations between factors were higher than in the original work. Both emotion-related impulsivity subscales correlated significantly with psychological disorder, engagement in and minutes of physical exercise per week. When included in multivariate regression models, the three factors explained 3.1%, and 29.2% of variance in amount of exercise per week and psychological disorder, respectively. In sum, findings indicated that the German TFI index has a robust three-factor structure that showed expected links to validity indicators, and novel effects in relation to physical exercise.

Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis.

Voluntary slow breathing (VSB) is used as a prevention technique to support physical and mental health, given it is suggested to influence the parasympathetic nervous system (PNS). However, to date, no comprehensive quantitative review exists to support or refute this claim. We address this through a systematic review and meta-analysis of the effects of VSB on heart rate variability (HRV). Specifically, we focus on HRV parameters indexing PNS activity regulating cardiac functioning, referred to as vagally-mediated (vm)HRV: (1) during the breathing session (i.e., DURING), (2) immediately after one training session (i.e., IM-AFTER1), as well as (3) after a multi-session intervention (i.e., AFTER-INT). From the 1842 selected abstracts, 223 studies were suitable for inclusion (172 DURING, 16 IM-AFTER1, and 49 AFTER-INT). Results indicate increases in vmHRV with VSB, DURING, IM-AFTER1, and AFTER-INT. Given the involvement of the PNS in a large range of health-related outcomes and conditions, VSB exercises could be advised as a low-tech and low-cost technique to use in prevention and adjunct treatment purposes, with few adverse effects expected.

Biochemical Basis of Resistance of Tobacco Callus Tissue Cultures to Hydroxyphenylethylamines.

It has been reported that hydroxyphenylethylamines, such as tyramine and octopamine, are toxic to tobacco (Nicotiana tabacum L.) callus cultures grown in the presence of auxins, whereas calli grown in the presence of cytokinins and crown gall cultures are resistant to these amines (P. Christou and K.A. Barton [1989] Plant Physiol 89: 564-568). In an attempt to understand the underlying mechanism of this resistance, we compared the fates of tyramine in tyramine-sensitive and tyramine-resistant tobacco tissue cultures (cv Xanthi nc). The very rapid formation of black-colored oxidation products from tyramine in sensitive tissues suggested that the toxicity might be caused by the oxidation of tyramine by phenol oxidases present in the tissues or released into the medium after subculture. This was confirmed through many indirect procedures (effect of exogenously added tyrosinase, induction of polyphenol oxidase [PPO] activity by auxin, etc.). The study of tyramine structure-activity relationships further suggested that the toxicity of tyramine might be due to the formation of indolequinones after oxidation by PPO. Subculture of calli grown on 2,4-dichlorophenoxyacetic acid in a medium containing benzyladenine triggered a slow decrease in PPO activity and dramatic increases in peroxidase and tyramine hydroxycinnamoyl transferase (THT) activities. THT was undetectable in calli grown on 2,4-dichlorophenoxyacetic acid but very active in tyramine-resistant crown gall cultures. Moreover, when [3H]tyramine was fed in vivo to tyramine-resistant tissues, it was rapidly integrated into cell walls in the wound periderm formed at the periphery of the calli. Both the conjugation of tyramine and its integration into cell walls could compete with the formation of toxic quinones and therefore play a part in the resistance. Thus, it seems likely that the control of the toxicity of hydroxyphenylethylamines by cytokinins results primarily from changes in the metabolism and the compartmentation of these amines.

L-Tyrosine beta-naphthylamide is a potent competitive inhibitor of tyramine N-(hydroxycinnamoyl)transferase in vitro.

L-Tyrosine beta-naphthylamide, a synthetic substrate designed to measure tyrosine aminopeptidase activity, is a potent inhibitor of hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase (THT) purified from elicited tobacco cell-suspension cultures. The inhibition is competitive, with the inhibitor binding reversibly to the tyramine binding site of the enzyme. Similar results were obtained with THT extracted from elicited potato cell-suspension cultures. Ki values were found to be 0.66 microM for the enzyme from tobacco and 0.3 microM for the enzyme from potato. L-Tyrosine 7-amido-4-methylcoumarin, a fluorogenic substrate for tyrosine aminopeptidases, the structure of which is close to that of L-tyrosine beta-naphthylamide. was also a powerful inhibitor, but slightly less effective with Ki values of 0.72 and 0.42 microM for tobacco and potato THT, respectively. L-Tyrosine beta-naphthylamide was rapidly hydrolysed when fed in vivo to tobacco or potato cell cultures or when incubated in crude enzymic extracts prepared from these cultures. This hydrolysis, which is presumably catalysed by aminopeptidases, precludes the use of L-tyrosine amides as inhibitors of THT in vivo.

Purification, characterization and partial amino acid sequencing of hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase from tobacco cell-suspension cultures.

We report the purification of hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase (THT) to apparent homogeneity in 12% yield from tobacco (Nicotiana tabacum L. cv. Xanthi) cell-suspension cultures elicited with a commercial preparation of pronase. The purification procedure employs only four chromatography steps and takes advantage of the fact that the transferase binds tightly both to phenyl-Sepharose and to hydroxyapatite. The native enzyme has a pI of 5.2 and consists of two identical or very similar subunits of approximately 24 kDa. The purified enzyme can synthesise a wide range of amides due to its relatively low specificity for cinnamoyl-CoA derivatives and hydroxyphenethylamines, but its best substrates are tyramine and feruloyl-CoA. THT follows Michaelis-Menten kinetics in the presence of low concentrations of feruloyl-CoA but negative cooperativity occurs when this concentration increases above 2.5 microM, resulting in a marked decrease of the affinity for tyramine. Large deviations from Michaelis-Menten kinetics are also observed when 3-methoxytyramine is used as acyl acceptor. The activity of tobacco THT is not affected by the addition of CaCl2 or MgCl2 but its maximal velocity is increased up to twofold by addition of ethanol to the assay mixture. It is inhibited in vitro by L-tyrosine benzyl ester, which binds reversibly to the tyramine-binding site. Experiments performed using L-tyrosine benzyl ester and caffeoyl-CoA as inhibitors confirm that feruloyl-CoA is the first substrate to add to the transferase in an ordered bi-bi mechanism. Part of the amino acid sequence of the transferase, elucidated by microsequencing of tryptic peptides, is also described.

Purification and Properties of Putrescine Hydroxycinnamoyl Transferase from Tobacco (Nicotiana tabacum) Cell Suspensions.

The enzyme putrescine hydroxycinnamoyl transferase (PHT) was purified 400-fold in 7.1% yield from tobacco (Nicotiana tabacum L. cv Xanthi) cell suspensions to a final specific activity of 45 nanokatal per milligram protein. The purification procedure involved conventional chromatography techniques (anion exchange chromatography, gel permeation, and hydroxylapatite chromatography) followed by chromatography on caffeoyl-cysteamine-Sepharose. This procedure led to considerable enrichment of a 50 kilodalton protein that could be further purified to near homogeneity by chromatofocalization (apparent isoelectric point = 8). PHT activity was repeatedly found associated with this protein, although approximately 66% of the enzymic activity was lost during chromatofocalization. Purified PHT exhibited the same properties as in the unpurified extract. It was not specific for putrescine and used other aliphatic diamines (mainly diaminopropane and cadaverine) as substrates. The most efficient phenolic substrate was caffeoyl-CoA, but cinnamoyl-, feruloyl-, sinapoyl-, and p-coumaroyl-CoA were also conjugated to putrescine, in decreasing order of activity. PHT could also use the artificial substrate p-fluorocinnamoyl-CoA.