Stress In Healthy Young Men Research Articles

Chronic Academic Stress Increases a Group of microRNAs in Peripheral Blood

MicroRNAs (miRNAs) play key roles in regulation of cellular processes in response to changes in environment. In this study, we examined alterations in miRNA profiles in peripheral blood from 25 male medical students two months and two days before the National Examination for Medical Practitioners. Blood obtained one month after the examination were used as baseline controls. Levels of seven miRNAs (miR-16, -20b, -26b, -29a, -126, -144 and -144*) were significantly elevated during the pre-examination period in association with significant down-regulation of their target mRNAs (WNT4, CCM2, MAK, and FGFR1 mRNAs) two days before the examination. State anxiety assessed two months before the examination was positively and negatively correlated with miR-16 and its target WNT4 mRNA levels, respectively. Fold changes in miR-16 levels from two days before to one month after the examination were inversely correlated with those in WNT4 mRNA levels over the same time points. We also confirmed the interaction between miR-16 and WNT4 3′UTR in HEK293T cells overexpressing FLAG-tagged WNT4 3′UTR and miR-16. Thus, a distinct group of miRNAs in periheral blood may participate in the integrated response to chronic academic stress in healthy young men.

Sex‐specific sympathetic responses to chemoreflex stress in healthy young men and women

While muscle sympathetic nerve activity (MSNA) responses to baroreceptor unloading are typically greater in men than women, it is unclear whether chemoreflex responses differ between the sexes. We tested the null hypothesis that MSNA responses to concurrent hypoxia and hypercapnia would not be different between sexes. Microneurographic recordings of fibular nerve MSNA, heart rate (HR) and mean arterial pressure (MAP; Finometer) were acquired from healthy young men and women (n=6 each, 25±3y). Females were tested in the early follicular phase of the menstrual cycle. Following baseline recordings, an oxygen partial pressure of 70 torr and an end tidal carbon dioxide partial pressure of 50 torr were achieved through a rebreathing protocol. Immediately succeeding the rebreathing protocol, an end‐inspiratory apnea commenced following inhalation of these gas concentrations. Baseline values for HR, MAP, and MSNA levels did not differ between the sexes. The HR and MAP responses to chemoreflex stress were also similar between men and women (P>0.05). However, during the apnea increases in MSNA burst frequency (+39±16 versus +23±9 bursts/min, P=0.03) and burst incidence (+54±21 versus +38±15 bursts/100 heart beats, P=0.04) were larger in women than men, respectively. These data suggest that sympathetic responses to an apneic hypoxic‐hypercapnic stimulus are greater in women than in men. Supported by NSERC and CIHR.

Effects of panel sex composition on the physiological stress responses to psychosocial stress in healthy young men and women

Men and women differ in regard to psychosocial stress responses. Biological and contextual factors are known to mediate these differences; however, few studies investigated their interaction. In the present study, we examined contributions of both contextual and biological factors to the stress response of young healthy adults. Men and women were exposed to a modified version of Trier Social Stress Test. The participants gave a speech in front of a panel of judges, composed of either male or female panelists. Both men, and women presented a cortisol increase only when exposed to opposite sex panelists. Interestingly, this effect was only observed in women in their follicular phase. This finding showed that the induction of a psychosocial stress response does not strictly rely on direct social evaluation, but also depends on the sex composition of the panel. Implications for future studies are discussed.

Lack of Effect of a High-Calorie Dextrose or Maltodextrin Meal on Postprandial Oxidative Stress in Healthy Young Men

Carbohydrate powder in the form of maltodextrin is widely used by athletes for postexercise glycogen resynthesis. There is some concern that such a practice may be associated with a postprandial rise in reactive oxygen and nitrogen species production and subsequent oxidation of macromolecules. This is largely supported by findings of increased oxidative-stress biomarkers and associated endothelial dysfunction after intake of dextrose. To compare the effects of isocaloric dextrose and maltodextrin meals on blood glucose, triglycerides (TAG), and oxidative-stress biomarkers in a sample of young healthy men. 10 men consumed isocaloric dextrose and maltodextrin powder drinks (2.25 g/kg) in a random-order, crossover design. Blood samples were collected premeal (fasting) and at 1, 2, 4, and 6 hr postmeal and assayed for glucose, TAG, malondialdehyde, hydrogen peroxide, nitrate/nitrite, and Trolox-equivalent antioxidant capacity. Significant meal effects were noted for glucose total area under the curve (p=.004), with values higher for the dextrose meal. No other statistically significant meal effects were noted (p>.05). With respect to the 2 (meal)x5 (time) ANOVA, no significant interaction, time, or meal effects were noted for any variable (p>.05), with the exception of glucose, for which a main effect for both meal (p<.0001) and time (p=.0002) was noted. These data indicate that carbohydrate meals, consumed as either dextrose or maltodextrin, pose little postprandial oxidative insult to young, healthy men. As such, there should be minimal concern over such feedings, even at high dosages, assuming adequate glucose metabolism.

Autobiographical memory after acute stress in healthy young men

Autobiographical memories have been found to be less specific after hydrocortisone administration in healthy men, resembling memory deficits in, for example, depression. This is the first study to investigate the effects of stress-induced elevated cortisol levels on autobiographic memory specificity and experience in healthy young men. Autobiographical memories were elicited by neutral and negative cue words, with instructions to recall either recent or remote memories. No effect of psychosocial stress was found on memory specificity or experience, but cortisol increases tended to be related to less specific, recent memories elicited by neutral cue words, especially when participants were physically aroused during memory retrieval. These results indicate that autobiographical memories are fairly resistant to an acute stressor in healthy young men, but that endogenous cortisol increases might be related to autobiographical memory retrieval. More research into the relation between endogenous cortisol increases and autobiographic memory retrieval is needed, especially in stress-related disorders.

Family history of cardiovascular disease is associated with cardiovascular responses to stress in healthy young men and women

Heightened cardiovascular stress responsivity is associated with cardiovascular disease, but the origins of heightened responsivity are unclear. The present study investigated whether disturbances in cardiovascular responsivity were evident in individuals with a family history of cardiovascular disease risk. Data were collected from 60 women and 31 men with an average age of 21.4 years. Family history of cardiovascular disease risk was defined by the presence of coronary heart disease, hypertension, diabetes or high cholesterol in participants’ parents and grandparents; 75 participants had positive, and 16 had negative family histories. Systolic and diastolic blood pressure (BP), heart rate and heart rate variability were measured continuously for 5 min periods at baseline, during two mental stress tasks (Stroop and speech task) and at 10–15 min, 25–30 min and 40–45 min post-stress. Individuals with a positive family history exhibited significantly greater diastolic BP reactivity and poorer systolic and diastolic BP recovery from the stressors in comparison with family history negative individuals. In addition, female participants with a positive family history had heightened heart rate and heart rate variability reactivity to stressors. These effects were independent of baseline cardiovascular activity, body mass index, waist to hip ratio and smoking status. Family history of hypertension alone was not associated with stress responsivity. The findings indicate that a family history of cardiovascular disease risk influences stress responsivity which may in turn contribute to risk of future cardiovascular disorders.

Sex Steroids, Cardiovascular Disease, and Hypertension

The roles that both male and female sex steroids play in mediating or protecting against cardiovascular disease (CVD) and hypertension are controversial. For example, whereas animal studies have strongly implicated androgens as being mediators of CVD and hypertension, human epidemiological studies have shown that with chronic disease, including hypertension, serum testosterone levels are actually reduced.1 Thus, whether androgens are truly causative of CVD is not clear. However, premenopausal women are typically protected from CVD and hypertension compared with men, and this has been hypothesized to be because of the protective effects of estrogens. The negative findings of Heart and Estrogen/progestin Replacement Study (HERS) I and II2,3 and Women’s Health Initiative (WHI)4,5 studies on hormone replacement therapy (HRT) in postmenopausal women have shaken our previous ideas that HRT was protective against CVD. In this short review, the latest findings regarding the roles of sex steroids in hypertension and CVD are discussed, questions yet to be answered are suggested, and some speculations are made. In both males and females, the hypothalamus secretes gonadotropin-releasing hormone, which stimulates the anterior pituitary to release both luteinizing hormone and follicular-stimulating hormone. Luteinizing hormone binds to receptors on thecal cells in ovaries of females and Leydig cells in testes of males to cause testosterone to be synthesized. Follicular-stimulating hormone, however, binds to receptors on granulosa cells in females or Sertoli cells in males and stimulates the synthesis of aromatase, which converts testosterone to estradiol. There are 2 main types of estrogen receptors, ERα and ERβ, but several variants of both have also been identified. ERβ is present in a greater number of tissues than is ERα, but both isoforms are present in kidneys and the vasculature. ERβ has been found to be the predominant isoform in human vascular smooth muscle cells. The androgen receptor …

Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men.

To evaluate the protective effects of taurine supplementation on exercise-induced oxidative stress and exercise performance, eleven men aged 18-20 years were selected to participate in two identical bicycle ergometer exercises until exhaustion. Single cell gel assay (SCG assay) was used to study DNA damage in white blood cells (WBC). Pre-supplementation of taurine, a significant negative correlation was found between plasma taurine concentration before exercise and plasma thiobaribituric-acid reactive substance (TBARS) 6 hr after exercise (r = -0.642, p<0.05). WBC showed a significant increase in DNA strand breakage 6 hr and 24 hr after exercise. Seven-day taurine supplementation reduced serum TBARS before exercise ( p<0.05) and resulted in a significantly reduced DNA migration 24 hr after exercise ( p<0.01). Significant increases were also found in VO(2)max, exercise time to exhaustion and maximal workload in test with taurine supplementation ( p<0.05). After supplementation, the change in taurine concentration showed positive correlations with the changes in exercise time to exhaustion and maximal workload. The results suggest that taurine may attenuate exercise-induced DNA damage and enhance the capacity of exercise due to its cellular protective properties.

Constantly low HDL-cholesterol concentration relates to endothelial dysfunction and increased in vivo LDL-oxidation in healthy young men

To test the hypothesis that low HDL-C concentration interferes with vascular endothelial function and lipoprotein oxidation, we measured endothelium-dependent flow mediated dilatation (FMD, %) of the brachial artery in young men ( n=20) classified prospectively into two groups on basis of having either low or high HDL-C concentration over the past 2 years. As an estimate of in vivo low-density lipoprotein oxidation (ox-LDL), we measured LDL diene conjugation. FMD was present in the group with high HDL-C concentration, but impaired in the group with low HDL-C (5.5±3.2 vs 0.2±1.2%, P<0.001). The group with high HDL-C level had significantly lower levels of ox-LDL compared to low HDL-C group (18.0±1.8 vs 22.9±4.4, P≤0.01). In all subjects, FMD correlated with HDL-C ( r=0.59, P=0.006), HDL 2-C ( r=0.62, P=0.004) and ox-LDL ( r=−0.56, P=0.013) but not with HDL 3-C ( r=0.16, P=0.52). We conclude that constantly low HDL-C concentration is related with endothelial dysfunction and increased oxidative stress in healthy young men, consistent with the idea that HDL particles may protect endothelium and inhibit the oxidation of LDL. These findings may offer insight into increased atherosclerosis associated with low HDL-C levels.

Short-term estradiol treatment enhances pituitary-adrenal axis and sympathetic responses to psychosocial stress in healthy young men

Short-term estradiol treatment enhances pituitary-adrenal axis and sympathetic responses to psychosocial stress in healthy young men

Cognitive coping strategies and blood pressure responses to real-life stress in healthy young men.

Cognitive coping strategies and blood pressure responses to real-life stress in healthy young men.

Cognitive coping strategies and blood pressure responses to real-life stress in healthy young men.

Coping style is an important feature in the understanding of the relation between real-life stress and associated blood pressure (BP) responses. In this study, 10 high- and 10 low-"self-focused-coping" (SFC) male college students were tested with ambulatory BP monitoring on two typical schooldays, one of which included an examination. It was found that the high-SFC subjects, defined as those who tend to keep to themselves and/or blame themselves in stressful situations, showed higher BP responses than the low-SFC subjects, but only on the exam day. Further, the high-SFC subjects showed higher BP during the exam but also had BP elevations that were sustained during other activities throughout the same day, including evening rest. These results are discussed in terms of the relation between psychological and physiological responding.