Time course of the corticosteroid-dopaminergic interaction during metyrapone and dexamethasone administration

Cortisol suppression after memory reactivation impairs later memory performance

Experiencing stressful or traumatic events can result in disabling clinical symptoms of maladaptive emotional memory retrieval, which are only partly addressed by the currently proposed treatments. Cortisol modulation has been shown to affect emotional memory retrieval and potentially reconsolidation, offering an opportunity for developing more efficient treatments for disorders with an emotional memory component. Here, we investigated if cortisol suppression after reactivation of emotional memories weakens later memory thereof. Forty healthy young men were tested in a randomized, placebo controlled, double-blind, and between-subject design, assigned either to a cortisol suppression (metyrapone) group or a placebo group. Participants of both groups, were presented with two emotional stories at an encoding session (Day 1). One of the two stories was later reactivated and followed by metyrapone vs. placebo administration (Day 3). Memory for both stories was tested at a recognition memory session (Day 7). In the group undergoing cortisol suppression after memory reactivation memory performance was weaker compared to the placebo group, tested four days after reactivation. This study shows that cortisol suppression can weaken memory for past events, possibly by altering reconsolidation processes and thus exerting long-lasting weakening effects on the original memory.

Anna-Monika Award Lecture, DGPPN Kongress, 2013: the role of the hypothalamic-pituitary-adrenal (HPA) axis in the pathogenesis of psychotic major depression

OBJECTIVES

This Anna Monika Award Lecture updates the role of the hypothalamic-pituitary-adrenal (HPA) axis in the pathogenesis and treatment of psychotic major depression (PMD).

METHODS

Published reports from our group and others on the clinical phenomenology (including cognition), HPA axis activity, and genetics of PMD are reviewed as are published trials of the GR antagonist, mifepristone.

RESULTS

Current prevalence of PMD is 0.4%. PMD patients demonstrate significant elevations in HPA activity (e.g., particularly high rates of dexamethasone non-suppression, high post-dexamethasone cortisol, etc.) as well as significant impairment in cognition (attention, executive function/response inhibition and verbal and visual memory). High cortisol levels correlate with a number of cognitive deficits (e.g., verbal memory). Allelic variants of the glucocorticoid receptor (GR) gene contribute significantly to both cortisol levels and to measures of psychosis; corticotropin-releasing hormone receptor 1 variants contribute to measures of depression and psychosis. GR antagonists have produced rapid improvement in psychotic symptoms, although failed trials indicate a therapeutic blood level that may require a dose of 1,200 mg/day that is much higher than the commonly tested 600 mg/day.

CONCLUSIONS

HPA axis over-activity appears to play a major role in the pathogenesis of PMD and is a target of drug development.

Glucocorticoid antagonists in neuropsychiatric [corrected] disorders

Neuropsychiatric disorders often involve considerable psychological stress and elevated cortisol activity. Glucocorticoid receptors have relatively low affinity for cortisol and are found distributed throughout the brain, particularly in the frontal cortex and hippocampus. In recent years, glucocorticoid receptors antagonists have been actively studied in both animal models of several disorders as well as a potential treatment in specific types of neuropsychiatric patients. Data from these various studies are reviewed with an emphasis on seven clinical disorders or problems: major depression with psychotic features, bipolar disorder, schizophrenia, cognitive disorders, (e.g., Alzheimer's disease and mild cognitive impairment), cognitive side effects of electroconvulsive therapy, and weight gain with atypical antipsychotic agents. Potential benefits and limitations are discussed.

Maturation and maintenance of cholinergic medial septum neurons require glucocorticoid receptor signaling

Glucocorticoids have been shown to influence trophic processes in the nervous system. In particular, they seem to be important for the development of cholinergic neurons in various brain regions. Here, we applied a genetic approach to investigate the role of the glucocorticoid receptor (GR) on the maturation and maintenance of cholinergic medial septal neurons between P15 and one year of age by using a mouse model carrying a CNS-specific conditional inactivation of the GR gene (GRNesCre). The number of choline acetyltransferase and p75NTR immuno-positive neurons in the medial septum (MS) was analyzed by stereology in controls versus mutants. In addition, cholinergic fiber density, acetylcholine release and cholinergic key enzyme activity of these neurons were determined in the hippocampus. We found that in GRNesCre animals the number of medial septal cholinergic neurons was significantly reduced during development. In addition, cholinergic cell number further decreased with aging in these mutants. The functional GR gene is therefore required for the proper maturation and maintenance of medial septal cholinergic neurons. However, the loss of cholinergic neurons in the medial septum is not accompanied by a loss of functional cholinergic parameters of these neurons in their target region, the hippocampus. This pinpoints to plasticity of the septo-hippocampal system, that seems to compensate for the septal cell loss by sprouting of the remaining neurons.

Double-blind antiglucocorticoid treatment in schizophrenia and schizoaffective disorder: a pilot study

BACKGROUND

Antiglucocorticoids, such as ketoconazole, have been investigated as antidepressant agents in major depression and other conditions. Despite evidence that a significant number of patients with schizophrenia and schizoaffective disorder are both hypercortisolemic and depressed, the antidepressant effects of antiglucocorticoids have never been assessed in these populations.

METHODS

Fifteen symptomatic patients with diagnoses of schizophrenia or schizoaffective disorder, who were at least partially treatment-resistant, were treated with ketoconazole, up to 800 mg/day, (n = 8) or placebo (n = 7) for four weeks in a double-blind manner. The study medication was added to a pre-stabilized antipsychotic and/or antidepressant medication regimen.

RESULTS

Ketoconazole treatment, compared to placebo, was associated with significant improvements in observer-rated depression, but not in subjectively rated depression, positive or negative psychotic symptom ratings, or cognitive performance scores.

CONCLUSIONS

These pilot data partially support the hypothesis that antiglucocorticoids reduce depressive symptoms in patients with schizophrenia and schizoaffective disorder, although objective and subjective ratings may not be similarly affected during a four-week course of treatment. Further studies with larger sample sizes, more extensive endocrine assessments and longer duration of drug administration seem warranted.

Dopaminergic function and the cortisol response to dexamethasone in psychotic depression

1. It has been hypothesized that psychotic symptoms in depression may be due to increased dopamine activity secondary to hypothalamic-pituitary-adrenal (HPA) axis overactivity. 2. To test this hypothesis, the authors examined the cortisol response to dexamethasone suppression test (DST, 1 mg orally) and multihormonal responses to apomorphine (APO, 0.75 mg s.c.)--a dopamine agonist--in 150 drug-free hospitalized patients with DSM-IV major depressive episode with psychotic features (MDEP, n=35), major depressive episode without psychotic features (MDE, n=74), or schizophrenia paranoid type (SCZ, n=41), and 27 hospitalized healthy controls (HCs). 3. MDEPs showed increased activity of the HPA system (i.e. higher post-DST cortisol levels) than HCs, SCZs and MDEs. However, there were no differences in adrenocorticotropic hormone (ACTH), cortisol, prolactin and growth hormone (GH) responses to APO between MDEPs and MDEs and HCs. On the other hand, SCZs showed lower APO-induced ACTH stimulation and a higher rate of blunted GH than HCs, MDEs and MDEPs, suggesting a functional alteration of the hypothalamic dopamine receptors in SCZs. 4. In the total sample and in each diagnostic group, DST suppressors and non-suppressors showed no differences in hormonal responses to APO. 5. These results suggest a lack of causal link between HPA axis hyperactivity and dopamine dysregulation. In contrast to schizophrenia, psychotic symptoms in depression seem not to be related to dopamine function dysregulation.

Influence of adrenal glands on the modulation of prolactin gene expression by the endogenous benzodiazepine ligand octadecaneuropeptide in the male rat pituitary gland

Recently, an 86-amino acid polypeptide with high affinity for diazepam binding sites, termed diazepam-binding inhibitor (DBI), has been found in the rat brain. DBI, as well as a peptide derived from DBI, the octadecaneuropeptide DBI[33-50] (ODN), interacts with the GABA(A) receptor complex. To investigate the role of these endogenous ligands for GABA(A) receptors on prolactin gene expression, we studied the effects of acute intracerebroventricular administration (4 h before sacrifice) of ODN on prolactin mRNA levels in the male rat. Because, in some neuropeptidergic systems, glucocorticoids play a role in the response to ODN, we also studied the influence of adrenal glands and the effect of dexamethasone administration in the response of prolactin gene expression to ODN. ODN injection produced an increase in prolactin mRNA levels. Adrenalectomy performed 5 days before sacrifice resulted in an increase in prolactin gene expression and also potentiated the stimulating effect of ODN. Because castration has been shown to decrease prolactin gene expression in the male rat, we used castrated and adrenalectomized animals to study the role of dexamethasone in the response of lactotrophs to ODN. In these steroid-deprived animals, dexamethasone treatment (for 4 days) decreased prolactin mRNA levels but did not modify the response to ODN. These data indicate that an endogenous neuropeptide interacting with the GABA(A) receptor complex can stimulate prolactin gene expression and suggest that the adrenal glands may produce factor(s) capable of decreasing prolactin mRNA. On the other hand, it does not appear that glucocorticoid hormones play a role in the effect of ODN on lactotroph activity.

A neuroendocrine role in cocaine reinforcement

Cocaine stimulates the secretion of corticosterone and ACTH, probably through a CRF-related mechanism, indicating that the drug activates the HPA axis. Indeed, cocaine has been reported to produce anxiety and to precipitate episodes of panic attack during chronic use and withdrawal in humans and to induce anxiogenic behavior in animals. Cocaine also alters benzodiazepine receptor binding in discrete regions of the rat brain. Some of these changes in binding are obviously related to the convulsions and seizures which are often observed in an acute cocaine overdose. However, data from behavioral studies have suggested that some of these effects may be related directly to cocaine reinforcement since receptor changes also were observed when binding in the brains of rats that self-administered cocaine was compared with that from animals that had received identical yoked, but non-contingent infusions of the drug. In this regard, pretreatment with the benzodiazepine receptor agonists chlordiazepoxide and alprazolam decreased cocaine self-administration without decreasing food-reinforced responding, suggesting that these effects were specific for cocaine. Since this attenuation of self-administration was reversed by increasing the unit dose of cocaine, it is likely that these drugs were decreasing cocaine reinforcement. In contrast, exposure to stress increases vulnerability to self-administer psychostimulants. In these experiments, low-dose cocaine self-administration was related directly to stress-induced increases in plasma corticosterone, such that plasma corticosterone was always greater than 150 ng/ml for rats which subsequently self-administered cocaine at doses of 0.125 mg/kg/infusion or lower, suggesting a threshold for the hormone in cocaine reinforcement. In other experiments, bilateral adrenalectomy completely abolished the acquisition of intravenous cocaine self-administration in naive rats, while metyrapone decreased ongoing self-administration. In addition, ketoconazole pretreatment resulted in patterns of self-administration that were virtually indistinguishable from that observed during saline extinction, suggesting that plasma corticosterone is not only important, but may even be necessary for cocaine reinforcement. The mechanisms through which adrenocorticosteroids alter cocaine reinforcement remain to be determined, but there is increasing evidence that the mesocorticolimbic dopaminergic system is involved. In particular, the medial prefrontal cortex appears to be at least one brain region where dopamine and adrenocorticosteroids may interact to affect cocaine reinforcement.

Longitudinal study of basal cortisol levels in healthy elderly subjects: evidence for subgroups

A group of 51 healthy elderly volunteer subjects participated in a 3- to 6-year longitudinal study of basal cortisol levels. Once per year basal cortisol levels were examined using hourly sampling over a 24-h period. Analyses of three cortisol measures (last measure obtained, mean cortisol levels across years, and the cortisol slope) revealed that the slope of the regression line measuring cortisol levels at each year was the most predictive measure of cortisol secretion over the years in this elderly population. Cortisol levels were shown to increase with years in one subgroup, to decrease in another, and to remain stable in a third. The age of the subjects was not related to either cortisol levels or to the pattern of change in cortisol secretion over years. Free and total cortisol levels were highly correlated and the groups did not differ with regard to plasma corticosteroid binding globulin. No group differences were observed for weight, height, body mass index, pulse, blood pressure and glucose. However, significant group differences were reported for plasma triglycerides levels as well as high density lipoproteins levels. Positive correlations were reported between the obsession/compulsion subscale of the SCL-90 questionnaire and the cortisol slope of subjects. Finally, previously reported group differences in neuropsychological performance are summarized. Thus, there exists considerable variation in hypothalamo-pituitary-adrenal function amongst aged humans. These results are consistent with recent animal studies showing the existence of subpopulations of aged rats which differ in hypothalamo-pituitary-adrenal activity and cognitive efficiency.