Activity and plasticity in the CA1, the dentate gyrus, and the amygdala following controllable vs. uncontrollable water stress

The level of controllability has been shown to modulate the effects of stress on physiology and behavior. In the present study, we investigated the effects of controllable vs. uncontrollable stressors on plasticity in hippocampal CA1, the dentate gyrus (DG), and basal amygdala nucleus (B) in the rat, using the electrophysiological procedure of long-term potentiation (LTP). A naive group was left undisturbed until the electrophysiological recording commenced. Rats of the two controllable stress groups were trained in the Morris water maze to locate an invisible underwater platform (the first group), or visible platform (the second group), thus escaping from the water, before the recording. The uncontrollable stress group underwent the same procedure (exposure time to water was adjusted to the averaged exposure time of the first controllable group) without the escape platform. We first assessed the effects of stress and controllability on LTP in CA1. Both controllable stressors and the uncontrollable stress impaired CA1 LTP, with a more robust effect induced by the uncontrollable stress. We further assessed the effects of the same procedures on LTP in DG and B. The uncontrollable stress enhanced LTP in DG and increased baseline responses (suggesting uncontrollable stress-induced plasticity) in the amygdala. All the stressors decreased amygdalar LTP. An assessment of plasma levels of corticosterone (CORT), following the behavioral procedures, revealed an enhancement in CORT release following the uncontrollable, but not controllable stress, indicating the uncontrollable condition as the most stressful. These findings provide insight into the differential effects of stress and stress controllability on different hippocampal subregions and the amygdala.     

Plasma postdexamethasone cortisol levels in schizoaffective disorder

The degree of hypothalamic-pituitary-adrenal (HPA) axis dysregulation in depressed patients with schizoaffective disorder was compared to that seen in patients with major depressive disorder with and without delusional features. The frequency of nonsuppression to dexamethasone was similar for all three diagnostic groups. Maximum postdexamethasone plasma cortisol was greater for delusional depressives, but did not differ between patients with major depressive and schizoaffective disorders. Modest correlations were found between postdexamethasone plasma cortisol levels, severity of illness, age, and recent weight loss, for patients with both major depressive disorder and delusional depression. For schizoaffective patients, associations between postdexamethasone plasma cortisol levels and various measures of severity of illness, but not age and recent weight loss, were found. Although HPA axis dysregulation occurs more frequently in all three of the studied diagnostic groups than in normal individuals, factors contributing to this dysregulation may be qualitatively different for schizoaffective patients.     

Hypothalamic-pituitary-adrenocortical function in mixed and pure mania.

There is little information about hypothalamic-pituitary-adrenocortical (HPA) axis function in mania, particularly in mixed states. We therefore investigated HPA function and its relationship to clinical state in 19 hospitalized manic patients meeting Schedule for Affective Disorders and Schizophrenia - Research Diagnostic Criteria for acute manic episodes, compared patients with and without a mixed presentation, and examined correlations between HPA activity and behavior. Data were available from 13-16 patients. Behavioral and biochemical analyses were conducted during a 15-d placebo period. Patients with mania had elevated cerebrospinal fluid (CSF) and urinary free cortisol excretion compared with healthy subjects, and did not differ from depressed patients in any cortisol measures. Mixed manics had significantly higher morning plasma cortisol, postdexamethasone plasma cortisol and CSF cortisol than pure manics. Five of 7 mixed manics and 3 of 9 pure manics were dexamethasone suppression test (DST) nonsuppressors. Afternoon plasma cortisol and CSF cortisol correlated significantly with depressed mood; urinary free cortisol correlated with anxiety. None of the cortisol measures correlated with mania or agitation scores. These data suggest that increased cortisol secretion is a characteristic of the depressed state in mixed manics, although pure manics may also have increased DST nonsuppression.     

Neurobiological effects of lumbar puncture stress in psychiatric patients and healthy volunteers

Several existing laboratory-based stress paradigms have significant shortcomings for assessing neurobiological correlates of stress in healthy volunteers and severely ill psychiatric patients. We have examined neuroendocrine effects of stress associated with the lumbar puncture (LP) procedure in drug-free depressed and schizophrenic patients and healthy volunteers. Healthy volunteers and depressed patients had significant stress-induced elevations in plasma levels of adrenocorticotropic hormone (ACTH), cortisol, and growth hormone associated with LP. In contrast, schizophrenic patients had no significant elevations in any of the neuroendocrine parameters. Depressed patients' cerebrospinal fluid norepinephrine levels were negatively correlated with stress-induced activation of the hypothalamic-pituitary-adrenal axis. In addition, depressed patients' basal plasma cortisol levels were strongly predictive of stress-related elevations in ACTH, cortisol, and growth hormone. Furthermore, stress-induced changes in schizophrenic patients' cortisol and ACTH levels were not correlated.     

Controllable and uncontrollable stress in humans: alterations in mood and neuroendocrine and psychophysiological function

The authors exposed 10 healthy human volunteers to the stress of loud (100 dB) noise under controllable and uncontrollable conditions on two separate days. Subjects reported higher self-ratings of helplessness, lack of control, tension, stress, unhappiness, anxiety, and depression; had greater hypothalamic-pituitary-adrenal axis function as measured by elevations in plasma adrenocorticotropic hormone; and had higher levels of sympathetic nervous system and electrodermal activity after the uncontrollable stress condition than after exposure to controllable stress. Thus, lack of control over even a mildly aversive stimulus can produce alterations in mood as well as neuroendocrine and autonomic nervous system changes in healthy subjects.     

Neuroendocrine identification of depressed patients.

Recent studies of hypothalamo--pituitary--adrenal (HPA) suppression in depressed patients indicate that these subjects often show abnormal early escape of plasma cortisol levels following an initial suppression. Non-depressed psychiatric inpatients usually show normal sustained HPA suppression. The responses of 49 depressed and 30 non-depressed patients have been analysed to develop criteria which can make the dexamethasone suppression test suitable for outpatient studies. The cortisol levels measured in a 24-hour urine collection and a single blood sample post-dexamethasone were sufficient to enable 61% of the depressed patients to be identified correctly at a confidence level of 90%, on the basis of at least one abnormal cortisol value. When both cortisol values were abnormal 35% of the depressed patient were identified correctly at a confidence level of 100%. Patients with "endogenous" depressive profiles had the most abnormal results. A normal response to this test will not necessarily exclude the diagnosis of primary depressive illness. An abnormal response to the test may be of help in confirming the diagnosis. With the simplified procedure outpatient studies may become possible.     

Pathophysiology of hypercortisolism in depression

OBJECTIVE: The mechanisms mediating hypercortisolemia in depression remain controversial. Adopting the biomarker strategy, we studied adrenocorticotropin (ACTH) and cortisol dynamics in hypercortisolemic and non-hypercortisolemic depressed in-patients, and in normal volunteers. METHOD: Deconvolution analysis of 24-h pulsatile secretion, approximate entropy (ApEn) estimation of secretory regularity, cross-ApEn quantitation of forward and reverse ACTH-cortisol synchrony, and cosine regression of 24-h rhythmicity. RESULTS: Hypercortisolemia was strongly associated with melancholic and psychotic depressive subtypes. Hypercortisolemic patients had elevated ACTH and cortisol secretion, mediated chiefly by increased burst masses. Basal ACTH secretion was increased, ACTH half-life was reduced, and mean 24-h ACTH concentration was normal. Cortisol secretion was increased in a highly irregular pattern (high ApEn), with high ACTH --> cortisol cross-ApEn (impaired feedforward coupling). Cortisol-mediated feedback on the secretory pattern of ACTH was normal. Hypercortisolemic depressed patients had normal programming of the central hypothalamo-pituitary-adrenal (HPA) axis pulse generator: ACTH pulse frequency, cortisol pulse frequency, circadian acrophases, and ApEn of ACTH secretion were normal. Responsiveness of the adrenal cortex to endogenous ACTH was normal. Non-hypercortisolemic patients resembled hypercortisolemic patients on ACTH regulatory parameters but had low total cortisol secretion. CONCLUSION: Increased ACTH secretion occurs in depressed in-patients regardless of cortisolemic status, confirming central HPA axis overdrive in severe depression. Depressive hypercortisolemia results from an additional change in the adrenal cortex that causes ACTH-independent, disorderly basal cortisol release, a sign of physiological stress in melancholic/psychotic depression.     

Platelet serotonin and plasma prolactin and cortisol in healthy, depressed and schizophrenic women

Serotonin (5-hydroxytryptamine, 5-HT) is involved in the regulation of hypothalamic-pituitary-adrenal axis (HPA) activity and prolactin (PRL) secretion. The present study examined the relationship between platelet 5-HT and plasma cortisol and PRL concentrations in 20 schizophrenic, 25 depressed, and 25 healthy women. At the time of blood sampling, the schizophrenic and depressed patients had been drug-free for at least 7 days. Platelet 5-HT, plasma cortisol and PRL concentrations were determined by spectrofluorimetric, radioimmunoassay and immunoradiometric methods, respectively. Platelet 5-HT concentration was significantly higher in schizophrenic patients than in depressed patients or in healthy controls, while it was significantly lower in depressed patients than in healthy controls or in schizophrenic patients. Plasma cortisol levels were significantly increased both in schizophrenic and in depressed patients compared with values in healthy controls. Values of plasma PRL were similar across groups. A significant correlation was found between platelet 5-HT and plasma cortisol, and platelet 5-HT and plasma PRL concentrations in healthy controls, but not in schizophrenic or depressed patients. There was no significant relationship between plasma PRL and cortisol levels in any of the groups. Our data, although obtained on peripheral biochemical markers, indicate that depression and schizophrenia are characterized by disturbed 5-HT transmission and dysregulated HPA axis activity.     

Effect of acute tryptophan depletion on the response to controllable and uncontrollable noise stress.

BACKGROUND: Previous research provides evidence linking serotonin (5-hydroxytryptamine, 5-HT) with stress and depression. The controllable/uncontrollable (C/UC) stress paradigm aims to generate a state/condition, namely a feeling of lack of control in the context of a stressor, which might be an important factor in precipitating a negative mood state. Acute tryptophan depletion (ATD) is a technique that produces a decrease in central 5-HT levels in vivo. This study investigated the role of 5-HT in the behavioral response to a C/UC stress paradigm with ATD. METHODS: Healthy adult volunteers were randomly assigned to receive either a TRP-supplemented (n = 15) or TRP-deficient (n = 13) amino acid drink. At 5 hours postdrink, volunteers were subjected to sessions of controllable and uncontrollable noise stress (100-dB white noise). Subjective ratings of mood were obtained before and after the interventions. RESULTS: Participants who received the tryptophan-depleting drink had greater self-report ratings of negative mood on visual analogue scales and the Profile of Mood States after the uncontrollable stress than did participants who received the balanced drink. CONCLUSIONS: The results suggest that 5-HT might play a role in providing resilience to uncontrollable stress. Additional studies with specific 5-HT pharmacologic probes will further clarify the results.     

Monoamine oxidase and cortisol response in depression and schizophrenia.

The relationship between hypothalamic-pituitary-adrenal (HPA) axis function and platelet monoamine oxidase (MAO) activity was examined in drug-free depressed (n = 32) and schizophrenic (n = 36) inpatients. HPA function was measured by determining plasma cortisol levels at 8:30 a.m. and 11 p.m. before, and 8:30 a.m., 4 p.m., and 11 p.m. after administration of 1 mg of dexamethasone (DEX). There was a significant correlation between platelet MAO activity and all post-DEX cortisol levels (8:30 a.m., 4 a.m., and 11 p.m.) in depressed patients, and MAO activity and pre-DEX cortisol levels (11 p.m.) in schizophrenic patients. MAO activity was significantly higher in depressed DST nonsuppressors than in suppressors, and there were more DST nonsuppressors in high-MAO groups as compared with low-MAO groups. Our results thus suggest a strong relationship between platelet MAO activity and HPA function in depressed patients. These biochemical markers are potentially useful in the identification of biochemically and clinically homogeneous subgroups of depressed patients.     

Effects of acute metabolic stress on the dopaminergic and pituitary-adrenal axis activity in patients with schizotypal personality disorder

BACKGROUND: Stress has been associated with the onset of schizophrenia and exacerbation of psychotic symptoms. Patients with schizotypal personality disorder (SPD), the prototypic schizophrenia spectrum disorder, do not develop the frank psychosis of schizophrenia and appear clinically to be less reactive to stress than schizophrenic patients. Schizophrenic patients demonstrate increased dopaminergic (DA) and hypothalamic-pituitary-adrenal-axis (HPA) activation following 2-deoxyglucose (2-DG), an acute metabolic (glycopyruvic) stressor, compared to healthy volunteers (HV). We hypothesized that SPD patients would demonstrate comparable or lower DA and HPA responses after 2-DG to HV. METHODS: Fifteen SPD patients and 13 HV were administered 2-DG (40 mg/kg, i.v.) in a double-blind, placebo-controlled, randomized protocol. The area under the curve (AUC) was determined for plasma HVA, ACTH and cortisol (utilizing baseline and post infusion indices). RESULTS: 2-DG induced significant increases in ACTH, cortisol and HVA concentrations in both groups and cortisol elevations were significantly lower in patients with SPD than in HV. CONCLUSIONS: Patients with SPD have a blunted cortisol and a normal dopaminergic response to 2-DG. These results are consistent with the hypothesis that SPD patients are better buffered against DA and HPA overactivation in response to stress.     

Intranasal insulin attenuates the hypothalamic-pituitary-adrenal axis response to psychosocial stress

Previous studies have shown that intranasally administered insulin exerts an inhibitory influence on the basal hypothalamic-pituitary-adrenal (HPA) axis activity. To date, however, it remains unclear as to whether intranasal insulin does furthermore affect HPA axis responsiveness in situations of stress. Here, we tested whether intranasally administered insulin attenuates the HPA axis response to psychosocial stress. Fifty minutes before being exposed to the Trier Social Stress Test (TSST), 26 healthy young male participants received a single intranasal dose of human insulin (40 I.U.) or placebo in a placebo controlled, double-blind between-subject design. Plasma cortisol, saliva cortisol, heart rate, and blood pressure were measured at resting baseline and in response to the TSST. Plasma cortisol (P<.001) and saliva cortisol (P<.001) increased in response to stress, as did heart rate (P<.001) and blood pressure (P<.001). Intranasal insulin did not influence plasma or saliva cortisol, heart rate, blood pressure, blood glucose, and plasma insulin levels at baseline. However, intranasal insulin diminished the saliva cortisol (two-way ANOVA; treatment by time interaction: P=.05) and plasma cortisol (two-way ANOVA; treatment by time interaction: P=.05) response to the TSST without affecting heart rate, and blood pressure stress reactivity. Our data show that a single intranasal insulin administration effectively lowers stress-induced HPA axis responsiveness. Intranasal insulin may offer a therapeutic potential to prevent hyperactivity of the HPA system.     

Salivary alpha-amylase and cortisol responsiveness following electrical stimulation stress in major depressive disorder patients

Major depressive disorder (MDD) is often associated with dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis by chronic stress. In comparison, psychosocial stress-induced activation of salivary α-amylase (sAA) functions as a marker of sympathoadrenal medullary system (SAM) activity. However, in contrast to salivary cortisol, sAA has been less extensively studied in MDD patients. The present study measured sAA and salivary cortisol levels in patients with MDD. The authors determined Profile of Mood State (POMS) and State-Trait anxiety Inventory (STAI) scores, Heart Rate Variability (HRV), and sAA and salivary cortisol levels in 88 patients with MDD and 41 healthy volunteers following the application of electrical stimulation stress. Patients with major depressive disorder were 8 points or more on Hamilton Depression Scale (HAM-D) scores. Tension-Anxiety, Depression-Dejection, Anger-Hostility, Fatigue, and Confusion scores in patients with major depressive disorder were significantly increased compared to healthy controls. In contrast, Vigor scores in patients with MDD were significantly decreased compared with healthy controls. There was no difference in heart rate variability measures between MDD patients and healthy controls. The threshold of electrical stimulation applied in MDD patients was lower than that in healthy controls. SAA levels in female MDD patients were significantly elevated relative to controls both before and after electrical stimulation. Finally, there were no differences in salivary cortisol levels between major depressive patients and controls. In the present study only three time points were explored. Furthermore, the increased secretion of sAA before and after stimulation could allude to an increased responsiveness of novel and uncontrollable situations in patients with MDD. These preliminary results suggest that sAA might be a useful biological marker of MDD.     

Hypothalamic-pituitary-adrenal axis function and suicidal behavior in depression.

Hypothalamic-pituitary-adrenal (HPA) axis function was examined in relation to suicidal behavior in depression. There were no significant differences between depressed patients who had or had not attempted suicide for either cerebrospinal fluid concentrations of corticotropin-releasing hormone, plasma cortisol levels predexamethasone or postdexamethasone, or for urinary-free cortisol outputs. However, depressed patients who had made a violent suicide attempt had significantly higher 4 PM and maximum postdexamethasone plasma cortisol levels, and significantly more of them were cortisol nonsuppressors than patients who had made nonviolent suicide attempts. A 5-year follow-up was carried out. There were no significant differences on indices of HPA function between depressed patients who did or did not reattempt suicide during the follow-up or who had never attempted suicide. These results suggest the possibility that dysregulation of the HPA axis may be a determinant of violent suicidal behavior in depression.     

Dorsomedial hindbrain participation in glucoprivic feeding response to 2DG but not 2DG-induced hyperglycemia or activation of the HPA axis

2-Deoxy- -glucose (2DG) is a glucose analogue that inhibits intracellular utilization of glucose and produces a characteristic behavioral response known as glucoprivic feeding. The area postrema (AP) is a caudal hindbrain structure shown previously to be involved in 2DG-induced glucoprivic feeding. In addition, peripheral administration of 2DG is known to elicit activation of both the hypothalamic-pituitary-adrenal (HPA) axis and the sympathoadrenomedullary system. The neural substrates for these neuroendocrine and neural responses to 2DG are not known although they may also involve the AP. The possible role of the AP in 2DG-induced feeding, activation of the HPA axis and hyperglycemia was investigated in Sprague–Dawley rats with lesions centered on the area postrema (APX) and sham-operated (SHM) rats administered 2DG (200 mg/kg) or physiological saline (1 ml/kg). Peripheral administration of 2DG evoked a feeding response in SHM rats that was abolished in APX animals. Interestingly, 2DG administered at this dose produced a significant increase in plasma corticosterone and plasma glucose in both SHM and APX rats for up to 4 h after drug treatment. Collectively, these findings suggest that the AP is involved in the behavioral (feeding) response to peripheral administration of 2DG, but does not appear to be a common neural substrate for the neuroendocrine (HPA axis) and sympathoadrenal (hyperglycemic) responses to this agent.     

Relationship between urinary free cortisol and CSF opioid binding activity in depressed patients and normal volunteers

We investigated the relationship between hypothalamic-pituitary-adrenal (HPA) activity, as measured by 24-hour mean urinary free cortisol (MUFC), and cerebrospinal fluid (CSF) opioid activity in patients with major affective disorder and normal volunteers. Among depressed patients, but not normal volunteers, mean 24-hour urinary cortisol values were significantly correlated with CSF opioid activity measured by radioreceptor assay, but were not significantly correlated with beta-endorphin immunoreactivity measured by radioimmunoassay. MUFC, as expected, was significantly higher in depressed patients than in normal volunteers. Mean values of CSF opioid activity and beta-endorphin immunoreactivity did not differ significantly in the two groups. The positive opioid-MUFC correlation found in the depressed group appeared to depend on patients who were cortisol hypersecretors. These data, using relatively crude measures of cortisol and opioid activity, are suggestive of a relationship between these two systems, particularly under "activated" conditions such as those observed in depression.     

Pituitary and adrenocortical responses to the ovine corticotropin releasing hormone in depressed patients and healthy volunteers

It has been suggested that limbic system-hypothalamic "overdrive" may be the underlying mechanism causing an augmented secretion of corticotropin releasing hormone (CRH), heightened adrenocortical responsiveness to corticotropin (adrenocorticotropic hormone) (ACTH), and alteration in cortisol feedback regulatory mechanisms as demonstrated by the dexamethasone suppression test. We examined pituitary and adrenocortical responses after morning administration of ovine CRH (oCRH) in 26 depressed patients and 11 healthy volunteers. Basal plasma ACTH concentrations were similar in both groups, whereas patients had a significantly diminished cumulative ACTH response after administration of oCRH. In contrast, basal total cortisol concentrations and cumulative cortisol responses to oCRH were similar in depressed patients and controls. Patients with melancholic features demonstrated the most profound ACTH blunting after oCRH, whereas patients separated according to dexamethasone suppression test results had similar ACTH and cortisol responses to oCRH. The present results extend data from prior studies utilizing oCRH in the evening and demonstrate a dysregulation of the functional integrity of the hypothalamic-pituitary-adrenocortical axis in depressive illness after a morning oCRH test at both central and peripheral hypothalamic-pituitary-adrenocortical axis sites.     

Hypothalamo-pituitary-adrenal activity in endogenously depressed post-traumatic stress disorder patients

We studied the hypothalamo-pituitary-adrenal (HPA) system in Vietnam veterans with post-traumatic stress disorder (PTSD) who also met Research Diagnostic Criteria for endogenous depression (MDD-ED). Over half also abused alcohol, and many complained of pain-confounding factors usually associated with increased HPA activity. Nonetheless, not even one patient had elevated basal plasma cortisol concentrations or an abnormal dexamethasone suppression test (DST); the subjects' post-dexamethasone cortisol values and plasma cortisol per ng plasma dexamethasone were in the low-normal range. These results highlight the biological heterogeneity of endogenous depression and its possible influence by past psychological trauma, and they raise questions about the use of current typological criteria for research purposes.     

Increase in concentration of waking salivary cortisol in recovered patients with depression

OBJECTIVE: Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis with elevated plasma cortisol levels is characteristic of acute major depression. However, it is unclear whether HPA axis abnormalities are present in fully recovered patients. An increase in salivary cortisol levels after waking provides a simple, dynamic measure of HPA axis activity. The authors measured this increase in recovered depressed patients and in a healthy comparison group. METHOD: Salivary cortisol levels were measured upon waking and at 15-minute intervals for the next hour in 31 medication-free, recovered depressed patients and in 31 matched healthy comparison subjects. RESULTS: The increase in salivary cortisol levels that followed waking was significantly higher in the patients. CONCLUSIONS: Greater secretion of cortisol may be present in depressed subjects after clinical recovery and withdrawal of medication. This may put patients at risk of further episodes of depression as well as comorbid medical conditions, such as coronary heart disease.     

Hypothalamic-pituitary-adrenal-cortical activity in anorexia nervosa and bulimia

We studied hypothalamic-pituitary-adrenal-cortical (HPA) activity in nine underweight women with anorexia nervosa, 12 women of normal body weight with bulimia, and nine control subjects. The measures of HPA activity were the pattern of plasma cortisol secretion over 24 hr and the responses of plasma cortisol to dexamethasone suppression and to low dose ACTH stimulation. The patients with anorexia nervosa had significantly elevated 24 hr concentrations of plasma cortisol compared to the controls and showed significantly less cortisol suppression following dexamethasone. There was no difference between patients with anorexia nervosa and controls in the rise in plasma cortisol following ACTH. On most measures of HPA activity, the normal weight patients with bulimia were indistinguishable from the controls. These results suggest that HPA activity is normal in most patients of normal body weight with bulimia and that the psychological and behavioral disturbances common to both anorexia nervosa and bulimia are, in the absence of significant weight loss, insufficient to produce major alterations in HPA activity.