Post-Encoding Stress Does Not Enhance Memory Consolidation: The Role of Cortisol and Testosterone Reactivity

Post-encoding stress and spatial memory consolidation: No significant associations with cortisol and DHEA reactivity

Memory consolidation is enhanced by post-encoding stress via cortisol, although the role of dehydroepiandrosterone (DHEA) remains uncertain. This study investigated the effect of the Maastricht Acute Stress Test (MAST) on psychological and hormonal (salivary cortisol and DHEA) responses and performance on a virtual reality object-location memory (OLM) task. The association between hormonal reactivity and OLM task performance was also investigated. Fifty-four participants aged 18-23 were randomly assigned to a stress group (n = 30) and a control group (n = 24). Participants completed an encoding trial of the OLM task and the MAST/control procedure in an acquisition session. A retrieval session 24 h later included verbal object and visual location recognition tests, as well as an object-context binding (OCB) trial. Results showed that the stress group reported significantly higher state anxiety and negative affect after the MAST, perceived as more stressful, painful, and unpleasant. This group also exhibited a significant increase in cortisol and DHEA levels in response to the MAST. Controlling for age, participants in the stress condition made fewer errors in recognising semantically unrelated objects and tended to complete the OCB trial in a shorter time. In addition, no associations were found between cortisol or DHEA reactivity and memory performance in either the stress group or the control group. Our data indicate that post-encoding stress enhances consolidation; however, no association was found between hormonal reactivity and this process, suggesting that these endocrine responses do not directly support the observed improvement in memory consolidation.

Spanish Validation of the Maastricht Acute Stress Test (MAST): A Cost-effective Stress Induction Protocol

The rise of stress studies has led to the existence of multiple stress induction protocols. However, cultural differences in stress reactivity are often overlooked. Therefore, this study aims to validate the Maastricht Acute Stress Test (MAST) in the Spanish population. A sample of 96 young adult participants was divided into an experimental group and a control group based on whether they were exposed to the MAST or a non-stressful control task. State anxiety and positive and negative affects were measured before and immediately after the protocol, while physiological stress (blood pressure and heart rate) was monitored throughout the experiment. The experimental group exhibited an increase in state anxiety, negative affect, and systolic and diastolic blood pressures after the MAST protocol. Participants with higher psychopathological risk presented higher scores of psychological stress than those with lower risk. Finally, it was found that participants with higher mathematical performance exhibited lower anxious reactivity following stressor exposure. Our results confirm the efficacy of the MAST and its validation for use in the Spanish population.

Gonads under stress: A systematic review and meta-analysis on the effects of acute psychosocial stress on gonadal steroids secretion in humans

Animal research has shown that the hypothalamus-pituitary-gonadal (HPG) axis is inhibited by (chronic and/or severe) stress, which can lead to impaired fertility and reproductive functioning, presumably caused by the inhibition of gonadal steroid secretion and in interactions with glucocorticoids. However, what has not been clarified is how acute psychosocial stress modulates gonadal steroid secretion in humans. Here we summarize the experimental research on the acute effects of stress on the secretion of gonadal steroids in humans. A systematic literature search revealed 21 studies (with N=881 individuals) measuring testosterone, progesterone or estradiol in response to a standardized acute laboratory stressor in healthy humans. Both our literature review and quantitative meta-analysis suggest that in humans, acute stress stimulates rather than inhibits HPG axis activity, although there is a considerable heterogeneity in the reported methods and results. Increased gonadal steroids in response to acute stress contrasts with many animal studies reporting the opposite pattern, at least regarding severe and/or chronic stressors. We discuss methodological issues and challenges for future research and hope to stimulate experimental studies within this area. A better understanding of these mechanisms is needed, and may have important implications for health and disease, as well as the modulation of various behaviors by acute stressors.

Hormone measurements and histomorphological observations in male Bactrian camels

The aim of this study was to investigate the effect of age on the hypothalamic-pituitary-gonadal (HPG) axis hormones and to determine the morphological changes of the testis. The Bactrian camels were divided into two groups based on their ages. The results showed that the testicular weight was significantly heavier in adult male camels than in pubertal male camels (P < 0.05). There were also significant differences between testicular length, testicular width, and testicular volume (P < 0.05). In the testes of both pubertal and adult male camels, Sertoli cells, spermatogonia, spermatocytes, round spermatids, and elongated spermatids were observed. Adult male camels had more Sertoli cells (P < 0.01) and elongated spermatids (P < 0.05). The concentrations of testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were higher in the plasma and testes of adult camels than in pubertal camels (P < 0.05). E2 concentrations were lower in adult camels than in pubertal camels (P < 0.05). The testosterone levels in testicular tissue were higher than in blood plasma in both adult and pubertal stage (P < 0.05). In conclusion, these findings provide supportive knowledge and show the significant differences in terms of testicular volume, testicular hormone concentrations, and testicular morphology between different developmental stages in Bactrian camels.

The association of cortisol/testosterone ratio and sleep quality with coronary heart disease: A case-control study in Chinese rural population

PURPOSE

There were limited studies that have probed into the combined effect of the cortisol/testosterone (C/T) ratio as a biomarker of stress and Pittsburgh Sleep Quality Index (PSQI) on coronary heart disease (CHD). This research aimed to explore the association of C/T ratio and PSQI with the risk of CHD in a rural Chinese population, as well as the interaction and combined effect between C/T ratio and PSQI on CHD.

METHODS

A case-control study was performed including 307 individuals without CHD and 307 patients drawn from Henan Rural Cohort. Logistic regression was utilized to survey the independent and joint effects of the C/T ratio and PSQI on CHD. To estimate the interaction impact of the C/T ratio and sleep quality (PSQI) on CHD, a cross-product term was introduced in the generalized linear model.

RESULTS

Higher C/T ratio and PSQI index scores are related to increased odds ratio for CHD (Odds ratios (ORs) and 95 % confidence interval (CI) were 1.17 (1.07, 1.29), p-trend < 0.001; 1.16 (1.09, 1.22), respectively). The odds ratio of C/T ratio for CHD increased with increasing PSQI in women (pinteraction = 0.018) and total population (pinteraction = 0.033). The combined group of high C/T ratio and high PSQI had the highest risk of CHD (Total: OR = 7.53, 95 % CI: 4.12-13.76).

CONCLUSIONS

The risk of CHD was associated with low testosterone levels, high C/T ratios, and high PSQI scores. Additionally, poor sleep quality aggravated the effect of high C/T ratio on coronary heart disease.