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Clinical Trial 2014; 35(6): 470-473 PubMed PMID: 25433841 Citation  Keywords:  Adolescent, Adult, Chemistry, Clinical:methods, Humans, Male, Oxytocin:blood, Perception:physiology, Reproducibility of Results, Saliva:metabolism, Young Adult,.   

OBJECTIVES: The neuroactive hormone oxytocin (OT) has significant influence on human behavior, and it has been measured peripherally in venous blood and in saliva in many behavioral neuroscience studies. Assessment of salivary hormone levels is popular due to non-invasiveness, but there is a controversy as to whether OT can be reliably measured in saliva and how possible time lags between plasma and salivary OT levels influence correlation.

DESIGN AND METHODS: In order to shed light on the question whether salivary and plasma OT levels correlate, we designed an experiment where healthy young men had to look at a presentation of trustworthy faces on a computer screen (faces were taken from an established database in trust research). During three points in time, plasma and saliva samples were collected and analyzed using ELISA.

RESULTS: Plasma and salivary OT levels did not correlate even when considering a time lag of 15 or 30 minutes.

CONCLUSIONS: Our results suggest that plasma and salivary OT levels do not correlate in healthy young men, and hence comparison of results across plasma and salivary studies is neither informative nor warranted. However, we recommend replicating this study based on mixed-gender samples....

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Journal Article 2014; 35(3): 236-241 PubMed PMID: 24977975 Citation  Keywords:  Adult, Brain-Derived Neurotrophic Factor:metabolism, Estradiol:metabolism, Female, Follicular Phase:metabolism, Humans, Luteal Phase:metabolism, Monitoring, Physiologic, Progesterone:metabolism, Saliva:metabolism, Young Adult,.   

OBJECTIVE: The aim of this study was to assess the relationship between brain-derived neurotrophic factor (BDNF) and sex hormones (estradiol [E2] and progesterone), using saliva samples obtained from healthy women.

METHODS: Forty female dental hygienist students were divided into groups according to being in the follicular phase or luteal phase. Saliva BDNF, E2, and progesterone levels were measured using a sandwich ELISA system. The correlation between these factors was analyzed using Spearman's index, and fluctuations of these levels in the whole menstrual cycle were investigated classifying the subjects by every 4 days according to the phase of their menstrual cycle.

RESULTS: Saliva BDNF variations strongly correlated with saliva E2 levels in the follicular phase (r = 0.721, p = 0.000) and luteal phase (r = 0.770, p = 0.000). The correlation coefficient showing the relationship between progesterone and BDNF levels in the luteal phase (r = 0.371, p = 0.157) was lower than that in the follicular phase (r = 0.631, p = 0.001). Moreover, the fluctuation of BDNF levels in the menstrual cycle followed a similar pattern to that of E2.

CONCLUSIONS: We found that saliva BDNF and E2 levels were closely related in healthy young women. In particular, for first time, that correlation was investigated throughout the menstrual cycle. Monitoring of saliva BDNF may yield insight into women's reproductive and mental health....

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Comparative Study 2012; 33(5): 525-529 PubMed PMID: 23090271 Citation  Keywords:  Adolescent, Estradiol:blood, Female, Humans, Loneliness, Male, Psychology, Adolescent, Saliva:metabolism, Sex Characteristics, Surveys and Questionnaires, Testosterone:blood,.   

OBJECTIVE: Loneliness is one of the psychological characteristics in adolescence, during which sex hormones are elevated. The elevation of sex steroid hormones is known to sculpture and remodel neuronal circuits, which cause behavioral characteristics in adolescence. The aim of the present study is to investigate the relationship between loneliness and sex steroid hormones, testosterone (T) and 17β-estradiol (E2).

METHODS: Fifty-eight adolescents (28 boys and 30 girls) participated in this study. The salivary levels of T and E2 were measured by Enzyme-Linked Immunosorbent Assay (ELISA). Loneliness was assessed by the UCLA loneliness scale, which is widely used as a self-administered questionnaire.

RESULTS: The results showed that Salivary E2 levels had positive relevance to loneliness in females, whereas there was no relationship in males. Salivary T level was not shown to be relevant with loneliness in either sex group.

CONCLUSIONS: These findings suggest that E2 has gender specific effects on loneliness in adolescent females....

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Comparative Study 2012; 33(4): 425-430 PubMed PMID: 22936252 Citation  Keywords:  Adult, Analysis of Variance, Biomarkers:metabolism, Computer Simulation, Female, Humans, Hydrocortisone:metabolism, Male, Maze Learning, Reaction Time, Reference Values, Saliva:metabolism, Self-Assessment, Sex Factors, Spatial Behavior, Stress, Psychologi.   

OBJECTIVES: Spatial learning is shown to be influenced by acute stress in both human and other animals. However, the intricacies of this relationship are unclear. Based on prior findings we hypothesized that compared to a control condition, a social stress condition would not affect spatial learning performance despite elevated biochemical markers of stress.

METHODS: The present study tested the effects of social stress in human males and females on a subsequent spatial learning task. Social stress induction consisted of evaluative stress (the Trier Social Stress Test, TSST) compared to a placebo social stress.

RESULTS: Compared to the placebo condition, the TSST resulted in significantly elevated cortisol and alpha amylase levels at multiple time points following stress induction. In accord, cognitive appraisal measures also showed that participants in the TSST group experienced greater perceived stress compared to the placebo group. However, there were no group differences in performance on a spatial learning task.

CONCLUSION: Our findings suggest that unlike physiological stress, social stress does not result in alterations in spatial learning in humans. It is possible that moderate social evaluative stress in humans works to prevent acute stress-mediated alterations in hippocampal learning processes.....

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Journal Article 2011; 32(5): 676-682 PubMed PMID: 22167151 Citation  Keywords:  Acoustic Stimulation:methods, Acoustics, Chromogranin A:metabolism, Humans, Hydrocortisone:metabolism, Male, Mental Processes:physiology, Neurosecretory Systems:physiology, Saliva:metabolism, Sound, Surveys and Questionnaires, Young Adult,.   

OBJECTIVE: In recent years, a new type of speaker called the parametric speaker has been used to generate highly directional sound, and these speakers are now commercially available. In our previous study, we verified that the burden of the parametric speaker was lower than that of the general speaker for endocrine functions. However, nothing has yet been demonstrated about the effects of the shorter distance than 2.6 m between parametric speakers and the human body. Therefore, we investigated the distance effect on endocrinological function and subjective evaluation.

METHODS: Nine male subjects participated in this study. They completed three consecutive sessions: a 20-min quiet period as a baseline, a 30-min mental task period with general speakers or parametric speakers, and a 20-min recovery period. We measured salivary cortisol and chromogranin A (CgA) concentrations. Furthermore, subjects took the Kwansei-gakuin Sleepiness Scale (KSS) test before and after the task and also a sound quality evaluation test after it. Four experiments, one with a speaker condition (general speaker and parametric speaker), the other with a distance condition (0.3 m and 1.0 m), were conducted, respectively, at the same time of day on separate days. We used three-way repeated measures ANOVA (speaker factor × distance factor × time factor) to examine the effects of the parametric speaker.

RESULTS: We found that the endocrinological functions were not significantly different between the speaker condition and the distance condition.

CONCLUSION: The results also showed that the physiological burdens increased with progress in time independent of the speaker condition and distance condition....

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Comparative Study 2011; 32(2): 158-163 PubMed PMID: 21552190 Citation  Keywords:  Adult, Circadian Rhythm:physiology, Computers, Humans, Light, Lighting, Melatonin:metabolism, Saliva:metabolism, Sleep:physiology, Students, Universities,.   

OBJECTIVES: Self-luminous electronic devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Melatonin suppression resulting from exposure to light at night has been linked to increased risk for diseases. The impact of luminous cathode ray tube (CRT) computer monitors on melatonin suppression was investigated.

DESIGN: Twenty-one participants experienced three test conditions: 1) computer monitor only, 2) computer monitor viewed through goggles providing 40 lux of short-wavelength (blue; peak λ ≈ 470 nm) light at the cornea from light emitting diodes (LEDs), and 3) computer monitor viewed through orange-tinted safety glasses (optical radiation <525 nm ≈ 0). The blue-light goggles were used as a "true-positive" experimental condition to demonstrate protocol effectiveness; the same light treatment had been shown in a previous study to suppress nocturnal melatonin. The orange-tinted glasses served as a "dark" control condition because the short-wavelength radiation necessary for nocturnal melatonin suppression was eliminated. Saliva samples were collected from subjects at 23:00, before starting computer tasks, and again at midnight and 01:00 while performing computer tasks under all three experimental conditions.

RESULTS: Melatonin concentrations after exposure to the blue-light goggle experimental condition were significantly reduced compared to the dark control and to the computer monitor only conditions. Although not statistically significant, the mean melatonin concentration after exposure to the computer monitor only was reduced slightly relative to the dark control condition.

CONCLUSIONS: Additional empirical data should be collected to test the effectiveness of different, brighter and larger screens on melatonin suppression....

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Comparative Study 2010; 31(5): 616-621 PubMed PMID: 21178944 Citation  Keywords:  Adult, Aged, Choice Behavior, Corticosterone:secretion, Female, Follow-Up Studies, Humans, Hydrocortisone:secretion, Impulsive Behavior:metabolism, Individuality, Male, Mass Spectrometry, Middle Aged, Models, Psychological, Reward, Saliva:metabolism, Sex .   

OBJECTIVES: Stress hormones have been associated with temporal discounting. Although time-discount rate is shown to be stable over a long term, no study to date examines whether individual differences in stress hormones could predict individuals' time-discount rates in the relatively distant future (e.g., six month later), which is of interest in neuroeconomics of stress-addiction association.

METHODS: We assessed 87 participants' salivary stress hormone (cortisol, cortisone, and alpha-amylase) levels and hyperbolic discounting of delayed rewards consisting of three magnitudes, at the time-interval of six months. For salivary steroid assays, we employed a liquid chromatography/ mass spectroscopy (LC/MS) method. The correlations between the stress hormone levels and time-discount rates were examined.

RESULTS: We observed that salivary alpha-amylase (sAA) levels were negatively associated with time-discount rates in never-smokers. Notably, salivary levels of stress steroids (i.e., cortisol and cortisone) negatively and positively related to time-discount rates in men and women, respectively, in never-smokers. Ever-smokers' discount rates were not predicted from these stress hormone levels.

CONCLUSIONS: Individual differences in stress hormone levels predict impulsivity in temporal discounting in the future. There are sex differences in the effect of stress steroids on temporal discounting; while there was no sex defference in the relationship between sAA and temporal discounting....

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Journal Article 2010; 31(5): 685-689 PubMed PMID: 21178943 Citation  Keywords:  Autonomic Nervous System:physiology, Circadian Rhythm:physiology, Electrocardiography, Female, Humans, Hydrocortisone:secretion, Male, Saliva:metabolism, Sleep:physiology, Sympathetic Nervous System:physiology, Time Factors, Vagus Nerve:physiology, Wakefu.   

: The current study focuses on autonomic nervous system activity during sleep as a physiological aspect of sleep quality, and investigated the associations between the cortisol awakening response (CAR) and autonomic activity during sleep and after awakening. Ambulatory electrocardiograms were obtained from 20 participants, who also provided saliva samples (at the time of awakening, and 30, 45, and 60 min after awakening) and rated the subjective quality of their sleep at home. Autonomic activity was assessed with the Lorenz plot indices, cardiac sympathetic index (CSI) and cardiac vagal index. Total salivary cortisol secretion after awakening was calculated as area under the curve with respect to ground (AUC(G)) and increase (AUC(I)). After controlling for confounding factors, including sleep duration and awakening time, cortisol AUC(G) and AUC(I) were both found to be negatively correlated with CSI during the 30 min before and after awakening: before (r = -0.526 and -0.601 respectively) and after (r = -0.540 and -0.493 respectively). Self-reported sleep quality was not associated with the CAR. These results suggest that the CAR is negatively affected by basal sympathetic activity immediately before and after awakening, but not affected by subjective sleep quality. Physiological arousals around the time of awakening might inhibit the CAR....

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