Namiko Ogawa

The diurnal patterns of salivary interleukin-6 and C-reactive protein in healthy young adults.

In recent years, salivary inflammatory markers, such as interleukin-6 (IL-6) and C-reactive protein (CRP), have been investigated regarding their relationships with psychosocial stress and stress-related diseases. This study investigated the diurnal patterns of salivary IL-6 and CRP in healthy young adults. Twenty-seven students (11 males and 16 females) participated in this study. The participants were instructed to provide saliva samples 8 times a day (at 0700, 0730, 1000, 1300, 1600, 1900, 2200, and 0100 h). For the duration of study, they were asked to wake up at 0700 h and go to bed after 0100 h. Twelve of the participants were asked to repeat this sampling procedure on two consecutive days to test the stability of the diurnal patterns. The salivary IL-6 levels peaked at awakening, gradually declined from morning to noon, and peaked again at midnight, before the participants went to sleep. The salivary CRP levels peaked at awakening, and they were lower during the daytime. The salivary IL-6 and CRP levels exhibited moderate to high stability over 2 days of sample collection. This study revealed that the salivary inflammatory markers had distinctive diurnal patterns.

Adrenal hormone response and psychophysiological correlates under psychosocial stress in individuals with irritable bowel syndrome

OBJECTIVE In this study, we investigated levels and relative ratios of adrenal hormones (including cortisol, dehydroepiandrosterone [DHEA], and DHEA-sulfate [DHEA-S]) and their psychophysiological correlates under acute psychosocial stress in individuals with irritable bowel syndrome (IBS). METHODS Fifty-three college students participated in the study (male: 42, female: 11; mean age: 22.64years), including 13 individuals with IBS (IBS group) and 40 individuals without IBS (control group). The participants were exposed to a standardized laboratory stressor, which included delivering a speech and performing a mental arithmetic task. We measured subjective stress levels and salivary cortisol, DHEA, and DHEA-S levels at relevant time points before, during, and after the tasks. RESULTS DHEA-S level and the DHEA-S/DHEA ratio in the IBS group were significantly lower than those in the control group, and the cortisol/DHEA-S ratio in the IBS group was higher than that in the control group throughout the experiment. In the IBS group, the appraisal of a threat was positively correlated with cortisol levels (r=0.61), and the appraisal of controllability was negatively correlated with cortisol levels (r=-0.64) and with the cortisol/DHEA ratio (r=-0.71). The control group showed a significant positive correlation between the appraisal of threat and cortisol levels (r=0.32). CONCLUSION The present study indicates that individuals with IBS had lower DHEA-S levels, and that their stressful cognitive appraisals under acute psychosocial stress caused the effects of cortisol to dominate. This adrenal hormone response may be involved in exacerbating abdominal symptoms in individuals with IBS.

Effect of day-to-day variations in adrenal cortex hormone levels on abdominal symptoms.

IntroductionThe hypothalamic-pituitary-adrenal axis is known to be related to abdominal symptoms, and the relationship between abdominal pain and cortisol secretory patterns has been previously investigated using a cross-sectional approach. Here, we investigated the effect of day-to-day variations in salivary cortisol and dehydroepiandrosterone-sulfate levels on abdominal symptoms in healthy individuals.MethodsEleven college students (4 males and 7 females) participated in this study. The participants were asked to collect their saliva immediately after awakening and before bedtime for eight consecutive days. They also completed a questionnaire about abdominal symptoms before bedtime. The linear mixed model was applied to analyze the effects of the day-by-day variability or the 8-day average adrenal hormone level (at awakening, before bedtime, slope from awakening to bedtime) on abdominal symptoms.ResultsThe day-to-day variability of cortisol levels before bedtime was negatively related with loose stool, while the day-to-day variability of the cortisol slope was positively correlated with loose stool. A low 8-day average dehydroepiandrosterone-sulfate level at awakening was positively related with frequent bowel movements, loose stool, and long bouts of severe abdominal pain. Likewise, a low 8-day average dehydroepiandrosterone-sulfate slope was positively related with long bouts of abdominal pain.ConclusionsLow cortisol levels before bedtime and a steeper diurnal cortisol slope during the day may be related to bouts of diarrhea during the day.

Salivary 3‐methoxy‐4‐hydroxyphenylglycol increases after awakening in healthy young adults

Levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) may reflect central noradrenergic activity. In this study, we investigated salivary MHPG changes after awakening, and explored their relationships with cortisol and peripheral autonomic activity. The participants were 25 college students. Saliva samples were collected on awakening and 30 min after awakening to determine MHPG and cortisol. Ambulatory electrocardiograms were obtained to assess heart rate, cardiac sympathetic index (CSI), and cardiac vagal index (CVI) before and after awakening. MHPG levels increased significantly during the first 30 min after awakening. Similarly, cortisol, heart rate, and CSI increased during the 30 min after awakening, but changes in MHPG did not correlate with changes in cortisol, heart rate, CSI, and CVI during that period. This study demonstrated that salivary MHPG levels increase after awakening, in common with cortisol, heart rate, and cardiac sympathetic activity.

Cortisol Reactivity to Psychosocial Stress and Attentional Disengagement from Threat Stimuli

Kenta KIMURA (Automotive Human Factors Research Center, National Institute of Advanced Industrial Science and Technology) Shuhei IZAWA (National Institute of Occupational Safety and Health) Nagisa SUGAYA (Association of Medical Science, Yokohama City University) Namiko OGAWA (Advanced Research Center for Human Sciences, Waseda University) Kosuke C. YAMADA (Faculty of Medicine, Saga University) Kentaro SHIROTSUKI (Faculty of Human Sciences, Musashino University) Yuichiro NAGANO (Faculty of Human Studies, Bunkyo Gakuin University) Toshikazu HASEGAWA (Graduate School of Arts and Sciences, The University of Tokyo)