The brain mineralocorticoid receptor and stress resilience.

Stress exposure activates the HPA-axis and results in the release of corticosteroids which bind to two receptor types in the brain: the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). While the role of the GR in stress reactivity has been extensively studied, the MR has received less attention. Nevertheless, pioneering in-depth studies over the past two decades have shown the importance of the brain MR in the processing of stressful information. Moreover, a membrane-bound MR mediating the rapid effects of cortisol was recently discovered. This review summarizes how the MR may play a role in stress resilience. Both preclinical and clinical studies suggest that the MR is an important stress modulator and influences basal as well as stress-induced HPA-axis activity, stress appraisal, and fear-related memories. These MR effects are mediated by both genomic and non-genomic MRs and appear to be at least partially sex-dependent. Moreover, the majority of studies indicate that high MR functionality or expression may confer resilience to traumatic stress. This has direct clinical implications. First, increasing activity or expression of brain MRs may prevent or reverse symptoms of stress-related depression. Second, individuals with a relatively low MR functionality may possess an increased stress susceptibility for depression. Nevertheless, the number of clinical MR studies is currently limited. In conclusion, the recent emergence of the MR as a putative stress resilience factor is important and may open up new avenues for the prevention and treatment of psychiatric disorders.

Oral contraceptives may alter the detection of emotions in facial expressions.

A possible effect of oral contraceptives on emotion recognition was observed in the context of a clinical trial with a corticosteroid. Users of oral contraceptives detected significantly fewer facial expressions of sadness, anger and disgust than non-users. This was true for trial participants overall as well as for those randomized to placebo. Although it is uncertain whether this is an effect of oral contraceptives or a pre-existing difference, future studies on the effect of interventions should control for the effects of oral contraceptives on emotional and cognitive outcomes.

Tryptophan depletion affects the autonomic stress response in generalized social anxiety disorder.

In generalized social anxiety disorder (gSAD), serotonergic dysfunctions are found, as well as abnormalities of the autonomic nervous system (ANS) in basal conditions and of the hypothalamic pituitary adrenal (HPA) axis in response to psychological challenges. These findings raise the question whether these phenomena are interrelated. Therefore we designed a study in which two groups with nine pair wise age and gender matched gSAD patients (total of 10 men and 8 women), who were successfully treated with a selective serotonin reuptake inhibitor (SSRI), underwent a tryptophan depletion challenge (TD) or a placebo condition. A TD procedure temporarily decreases serotonergic neurotransmission. In order to activate the stress system the TD/placebo challenge was combined with a public speaking task. We assessed ANS responses, as measured with the promising new marker salivary alpha-amylase (sAA), and HPA-axis responses, as measured with salivary cortisol. The most important result was that the TD group showed a significant larger sAA response to the public speaking task as compared to the placebo group, reflecting hyperresponsivity of the ANS in this group, whereas no differences were seen in cortisol responses. This suggests that in gSAD there is a vulnerability of the ANS more than the HPA-axis.

Mental performance in old age dependent on cortisol and genetic variance in the mineralocorticoid and glucocorticoid receptors.

Depression and cognitive decline have been associated with changes in circulating cortisol concentrations. Cortisol exerts its functions through mineralocorticoid (MR) and glucocorticoid (GR) receptors. However, data on the influence of variations in the MR and GR genes on depressive symptoms and cognitive functioning in older adults are scarce. Therefore, we explored the impact of MR-215G/C, MR-I180V, GR-ER22/23EK, GR-N363S, and GR-BclI polymorphisms on these end points in the population-based Leiden 85-plus Study. This prospective study includes 563 participants aged 85 years and older, with a mean follow-up of 4.2 years. In this study, high morning cortisol levels (per 1 SD cortisol) associated with impairments in global cognitive functioning (p=0.002) at baseline (age 85). These impairments were mainly attributable to lower attention (p=0.057) and slower processing speed (p=0.014). Similar effects were also observed during follow-up (age 85-90), where participants with higher cortisol levels (per 1 SD cortisol) had impaired global cognitive functioning (p=0.003), as well as impairments in attention (p=0.034) and processing speed (p=0.013). Changes in depressive symptoms were observed for the MR-I180V single-nucleotide polymorphism (SNP), where during follow-up the prevalence of depressive symptoms was higher in the 180V-allele carriers (p=0.049) compared to noncarriers. Dependent on these polymorphisms, no differences in overall and in specific domains of cognitive functioning were observed. In conclusion, the MR-I180V SNP has a specific effect on depressive symptoms, independent from cognitive functioning, and other polymorphisms in the MR and GR genes. In contrast, these genetic variants in the MR and GR genes do not influence cognitive functioning in old age.

Plasma cortisol and norepinephrine in Alzheimer's disease: opposite relations with recall performance and stage of progression.

OBJECTIVE: Alzheimer's disease (AD) is characterized by effortful retrieval memory impairments, loss of hippocampal neurons and elevated plasma cortisol (CORT) concentrations. The latter could induce further memory decline. AD is also characterized by increased central and peripheral noradrenergic activity. Since noradrenergic function is involved in memory formation, this upregulated function could counteract memory decline. The aim of the present study was to test these hypotheses using plasma norepinephrine (NE) as a noradrenergic parameter, and recall of the prerecency part of neutral valence word lists as a measure of effortful retrieval. METHODS: Area under the curve (AUC) of morning, midday and afternoon plasma CORT and plasma NE concentrations was related to two measures of recall performance, ie summated recall scores of the prerecency and recency parts of three word lists, and to the stage of the Clinical Dementia Rating (CDR). RESULTS: Partial correlation between each hormone AUC value and prerecency recall performance, controlling for the effect of the other hormone, showed opposite relations between recall and either plasma CORT or NE. Similar stronger correlations were found with the CDR score. CONCLUSIONS: Plasma CORT and NE are oppositely related with effortful retrieval and the stage of progression in AD.

Depression with above-normal plasma vasopressin: validation by relations with family history of depression and mixed anxiety and retardation.

An anxious-retarded subtype of depression has been derived from the DSM-IV category of melancholia. It is defined by combined high scores for anxiety and retardation, and is related to family history of depression and increased plasma vasopressin (AVP) levels. Central problems concerning this hypothesized subcategory are whether elevated plasma AVP is related to family history, whether it would be better operationalized by a cut-off level for plasma AVP than as continuous variable, and whether the anxious-retarded phenotype would be better described in terms that account for full variability of mixed anxiety and retardation. A previous study suggested that above-normal plasma AVP was a more useful endophenotypic parameter than plasma AVP as a continuous variable. To answer these and related questions, 81 patients were investigated. Receiver Operating Characteristic analyses yielded a cut-off value of 5.56 pg/ml for above-normal plasma AVP, log-transformed plasma AVP (ln (AVP)) was used as continuous variable, and the correlation between anxiety and retardation was used to account for full variability of the anxious-retarded phenotype. Family history was related to above-normal plasma AVP (n = 16) and non-significantly to ln (AVP). Depression with above-normal plasma AVP, as well as familial depression with above-normal plasma AVP, showed a high correlation between anxiety and retardation, and this correlation was significantly higher than that found in the depressed patient control groups. The data support the delimitation of a largely familial depression with above-normal plasma AVP, vasopressinergic activation of the hypothalamus-pituitary-adrenal axis and a variable anxious-retarded phenotype.

Recall performance, plasma cortisol and plasma norepinephrine in normal human subjects.

This study investigated hypothalamic-pituitary-adrenal (HPA)-axis and sympathetic nervous system (SNS) correlates of recall performance in normal human subjects. Twenty-two normal human subjects were given one memory task: short-term recall of unrelated non-organizable lists of neutral words, in immediate recall conditions. Two types of memory were individualized: measures reflecting effortful processing and measures reflecting automatic processing, which were related to 3 daytime plasma cortisol (CORT) and plasma NE values, and assessed after venipuncture. It was hypothesized that plasma CORT is positively related and plasma norepinephrine (NE) is negatively related to effortful processing. Pearson correlation was computed and regression analysis was performed. Positive correlation appeared between plasma CORT values and negative correlation appeared between plasma NE values and measures reflecting effortful processing. However, stepwise multiple regression analysis showed that only morning plasma CORT values are functionally positively and afternoon plasma NE values are functionally negatively related to effortful processing. This suggests that morning HPA-axis activities enhance and afternoon SNS activities inhibit effortful processing.

Fluvoxamine reduces responsiveness of HPA axis in adult female BPD patients with a history of sustained childhood abuse.

The aim of the study is to test whether fluvoxamine affects the function of the hypothalamic pituitary adrenal (HPA) axis in female borderline (borderline personality disorder, BPD) patients with and without a history of sustained childhood abuse. Special attention is given to the presence of comorbid major depressive disorder (MDD) and post-traumatic stress disorder (PTSD). The HPA axis of 30 female BPD patients with (n = 17) and without (n = 13) a history of sustained childhood abuse was challenged with a combined dexamethasone and corticotropin releasing hormone test (DEX/CRH test) before and after 6 (n = 14) and 12 (n = 16) weeks of fluvoxamine treatment (150 mg/day). Both 6- and 12-week fluvoxamine treatments were associated with a significant and robust reduction of the adrenocorticotrophic hormone (ACTH) and cortisol response to the DEX/CRH test. The magnitude of the reduction was dependent on the presence of sustained childhood abuse, but not on the presence of comorbid MDD or PTSD: patients with a history of sustained childhood abuse showed the strongest reduction in ACTH and cortisol. In conclusion, Fluvoxamine treatment reduces the hyperresponsiveness of the HPA axis in BPD patients with a history of sustained childhood abuse. This effect is likely to be obtained in the first 6 weeks of treatment.

Placebo-controlled comparison of three dose-regimens of 5-hydroxytryptophan challenge test in healthy volunteers.

Single-dose administration of 5-hydroxytryptophan (5-HTP) is regularly used as a challenge test of the serotonergic system. The use of 5-HTP has been limited by an apparent small window between the occurrence of neuroendocrine endpoints and the occurrence of side effects. Therefore, many dosing strategies have been tried with and without concurrent administration of carbidopa, a peripheral inhibitor of the decarboxylation from 5-HTP to serotonin. The aim of the current study was to assess the relation between pharmacokinetics and pharmacodynamics of 5-HTP. Twelve healthy male volunteers were included in a placebo-controlled, randomized, four-way crossover, double-blind, single-dose investigation of oral 5-HTP with or without coadministration of carbidopa. The four dose regimens were placebo, 5-HTP 100 mg, 5-HTP 200 mg, and 5-HTP 100 mg with coadministration of carbidopa 100 mg and 50 mg at 3 hours before and 3 hours after the administration of 5-HTP, respectively. The last regimen resulted in a doubling of the elimination half-life, an apparent clearance at least 14 times smaller, and a 15.4 times greater area under the curve compared with 5-HTP 100 mg without carbidopa. Furthermore, it was the only regimen to induce a significant change in cortisol and prolactin. It did not induce any change in subjective psychologic symptoms or cardiovascular parameters, but it was the only regimen to induce some nausea in three participants. The authors conclude that this regimen of 5-HTP 100 mg plus carbidopa is a relatively simple, effective, and tolerable challenge of the presynaptic serotonergic system. Further increase of the dose of 5-HTP might improve the size of the effect on endpoints as long as the tolerability remains good.

Estimation of plasma serotonin using isopycnic centrifugation.

The valid measurement of the concentration of serotonin (5-HT) in blood plasma is important when using the platelet as a model for the serotonergic neuron. The assay is hampered by the release of 5-HT by (residual) platelets during the preparation for assay. We developed an isopycnic method that separates cells gently and completely from plasma by centrifuging a diluted Percoll density-gradient to which whole blood was added. In this study this method was compared with the usual differential centrifugation method. The isopycnic method on average resulted in nine times lower levels of plasma 5-HT. This difference was linearly related to the number of residual platelets in plasma after differential centrifuging. The proportion of intra-individual variation decreased three-fold. Therefore, the use of a Percoll density-gradient may lead to a more precise and more accurate estimate of the level of plasma 5-HT. Copyright 2000 John Wiley & Sons, Ltd.