Published by Elsevier
Print ISSN: 0306-4530
The relationships between urinary levels of alpha 1-microglobulin (alpha 1M) and ulinastatin (UT) were investigated in C57BL/6J mice, a species which reportedly possesses the gene similar to that of humans for synthesizing the precursor protein of alpha 1M and UT. A positive correlation was established in normal mice. However, repetitive administrations (20 mg/kg, IP, four administrations/12 h) of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) nullified the positive correlation. A similar phenomenon was induced by ICV-administered MPTP (18 and 36 micrograms) in the animals. Furthermore, L-dopa administration (50 mg/kg, IV) in MPTP-treated (1 week after the final IP administration of MPTP) mice reversed the tendency of MPTP, although the agent alone did not affect the positive correlation in normal mice. These results suggest that nullification of the positive correlation probably was induced by the central effects of MPTP. We have found previously that the lack of a positive correlation between urinary levels of alpha 1M and UT distinguishes Parkinson's disease from other neuropsychiatric diseases such as dementia (Alzheimer-type and vascular dementia), schizophrenia and mood disorders. Our present results displayed a phenomenon that the lack of correlation between urinary levels of alpha 1M and UT in patients with Parkinson's disease is reproducible in MPTP-treated mice.
The possible participation of the endogenous opioid system (EOS) in the negative feedback of the hypothalamic-pituitary-adrenal axis (HPA-a) activated by low doses (1 mg) of dexamethasone (Dex) was investigated. Ten male healthy subjects (mean age 31.5 +/- 1.9 SEM) were studied on 2 separate days, in a double-blind, cross-over and placebo-controlled design. All subjects were pretreated with 1.0 mg Dex orally the night (2300 h) before both test days. On the study days, subjects were admitted at 0700 h for cannula insertion; the administration of an i.v. bolus of either naloxone (Nal) (1.0 mg/kg) or saline solution (Sal) i.v. was started at 0900 h. Before and following each infusion, mood was measured by a Visual Analogue Scales (VAS) and by the Affective Quality Scale (AQS) every 30 min and blood samples were taken at 15-min intervals. Blood pressure and heart rate were also monitored. Before Dex administration, plasma cortisol levels were within the normal range in all subjects (210.4 +/- 13 ng/ml), while after 9 h after Dex cortisol levels showed the expected significant (p < 0.01) decrease (11.5 +/- 1.9 and 15.04 +/- 0.7 ng/ml for Sal and Nal test days respectively). There were no detectable increases in plasma cortisol levels following either Nal nor Sal administration. However, there was a Nal-induced significant increase in LH (p < 0.01) thus indicating that an effective opioid blockade at the level of the hypothalamic-pituitary unit occurred. There were also a mild and selective Dex + Nal-induced dysphoric (mood factors related to subjects perception of their cognition) and bradycardic effects (p < 0.05). These results suggest that the EOS is not directly involved in the negative feedback triggered by low doses of Dex of the HPA-a, and that there might be a possible glucocorticoid-opioid interaction for the modulation of some aspects of mood.
Depression is characterized by hypothalamo-pituitary-adrenocortical (HPA) axis hyperactivity. In this major mood disorder, neurosteroids and neurotrophins, particularly brain-derived neurotrophic factor (BDNF), seem to be implicated and have some antidepressant effects. BDNF is highly involved in regulation of the HPA axis, whereas neurosteroids effects have never been clearly established. In this systematic in vivo study, we showed that the principal neuroactive steroids, namely dehydroepiandrosterone (DHEA), pregnenolone (PREG) and their sulfate esters (DHEA-S and PREG-S), along with allopregnanolone (ALLO), stimulated HPA axis activity, while also modulating central BDNF contents. In detail, DHEA, DHEA-S, PREG, PREG-S and ALLO induced corticotropin-releasing hormone (CRH) and/or arginine vasopressin (AVP) synthesis and release at the hypothalamic level, thus enhancing plasma adrenocorticotropin hormone (ACTH) and corticosterone (CORT) concentrations. This stimulation of the HPA axis occurred concomitantly with BDNF modifications at the hippocampus, amygdala and hypothalamus levels. We showed that these neurosteroids induced rapid effects, probably via neurotransmitter receptors and delayed effects perhaps after metabolization in other neuroactive steroids. We highlighted that they had peripheral effects directly at the adrenal level by inducing CORT release, certainly after estrogenic metabolization. In addition, we showed that, at the dose used, only DHEA, DHEA-S and PREG-S had antidepressant effects. In conclusion, these results highly suggest that part of the HPA axis and antidepressant effects of neuroactive steroids could be mediated by BDNF, particularly at the amygdala level. They also suggest that neurosteroids effects on central BDNF could partially explain the trophic properties of these molecules.
Raised maternal anxiety during pregnancy is associated with increased risk of adverse neurodevelopmental outcomes for her child. The mechanisms underlying this are not known but animal studies suggest prenatal stress may alter the function of the placenta. Here we determined whether maternal prenatal anxiety was associated with a downregulation of placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), the enzyme which metabolises cortisol. We recruited mothers the day before delivery by elective caesarean, and gave them the Spielberger Trait and State anxiety and Edinburgh Depression self-rating scales. Placentae were collected and aliquots stored for later analysis. Prenatal Trait anxiety was negatively correlated with placental 11β-HSD2 mRNA expression (r=-0.40, p<0.01, n=56). Results were similar with male and female fetuses (r=-0.39, p=0.04, n=28; r=-0.40, p=0.03, n=28) respectively. Results were also significant with State anxiety (r=-0.27, p=0.05, n=56) but somewhat weaker for depression (r=-0.20, p=0.13, n=56). Preliminary analyses on a subset of cases (n=25) suggested parallel results for enzyme activity. These findings provide evidence for an association between prenatal maternal mood and downregulation of placental 11β-HSD2. Results are consistent with raised maternal anxiety being associated with increased fetal exposure to maternal cortisol, and support the hypothesis that this may be one mechanism underlying fetal programming by prenatal stress.
Plasma cortisol and 11-deoxycortisol were measured in 30 depressed patients and 110 normal volunteers before and after a 1.0 mg dexamethasone suppression test (DST). Post-dexamethasone plasma cortisol, 11-deoxycortisol and the cortisol/11-deoxycortisol ratio were significantly higher in the depressives compared to the controls, even when age and sex were taken into account. Pre-dexamethasone plasma cortisol, post-dexamethasone cortisol, 11-deoxycortisol and their ratio were significantly higher in the cortisol nonsuppressors than in the suppressors. The measurement of post-dexamethasone 11-deoxycortisol and the ratio did not differentiate between endogenous and reactive depression. Using the normative data, we explored several methods for determining a criterion value to define abnormal post-dexamethasone plasma 11-deoxycortisol and the cortisol/11-deoxycortisol ratio in depressed patients. All showed poor sensitivity and a low positive predictive value for depression. The measurement of 11-deoxycortisol thus does not enhance the clinical utility of the DST.
Investigation of the plasma concentrations of five adrenal steroids—corticosterone (B), 11-deoxycorticosterone (DOC), 11-deoxycortisol (S), cortisol (F) and cortisone (E)—before and after an overnight dexamethasone suppression test (DST) revealed that the sensitivity of the DST can be increased by using a multisteroid analysis. None of the individual plasma steroids was superior in discriminating between six normal and six endogenously depressed (ED) women. The ratios of F/S and B/DOC were markedly increased in most of the ED patients in comparison to the healthy controls, indicating an activation of adrenal 11β-hydroxylase in ED. Thus after an overnight DST, more specific indicators of adrenal activity derived from multisteroid analysis may increase the sensitivity of this valuable laboratory test.
A proportion of subjects with symptoms of posttraumatic stress disorder (PTSD) are unresponsive to specialized psychotherapy, but a biological basis for this has not been described. To observe whether differences in cortisol or its metabolites predict or correlate with response to therapy for PTSD symptoms, cortisol and its metabolites were measured from urine samples at pre-treatment, at the conclusion of psychotherapy, and at 3-month follow-up. 28 survivors of the World Trade Center attacks on September 11, 2001 seeking psychological treatment for PTSD symptoms received four sessions of either exposure therapy or supportive counseling, followed by up to 10 sessions of prolonged exposure in a specialized PTSD treatment program at a private hospital serving the New York City metropolitan area. 24-h mean integrated cortisol excretion was assessed by radioimmunoassay (RIA); urinary free cortisol and metabolites cortisone, 5alpha-tetrahydrocortisol (5alpha-THF), 5beta-tetrahydrocortisol, and tetrahydrocortisone were assessed by gas chromatography-mass spectrometry (GC-MS); and indices of enzyme activity for 5alpha- and 5beta-reductase and for the 11beta-hydroxysteroid dehydrogenases were derived from the metabolite and glucocorticoid measures. 5alpha-Reductase activity was significantly lower at pre-treatment among non-responders, whereas there were no significant pre-treatment differences between responders and non-responders in any other hormone or metabolite level. In repeated measures analyses across the three time points, 5alpha-reductase activity, as well as 5alpha-THF and total glucocorticoids, significantly differed between responders and non-responders. For urinary cortisol measured by RIA, there was a significant groupxtime interaction indicating that, although not different at pre-treatment, urinary cortisol levels declined over time in the non-responder group, such that by follow-up, lowered cortisol significantly distinguished non-responders from responders. Indices of 5alpha-reductase activity, including 5alpha-THF and total glucocorticoids, were significantly negatively correlated with avoidance symptom severity at pre-treatment. At follow-up, indices of 5alpha-reductase activity were significantly negatively correlated with severity of all three PTSD symptom clusters and with total PTSD severity scores. Lower 5alpha-reductase activity is associated with avoidance severity and predicts non-responsiveness to psychological treatment for PTSD symptomatology. Relatively diminished 5alpha-reductase activity may mark a state of primary vulnerability, perhaps via attenuated peripheral catabolism of cortisol resulting in the suppression of hypothalamic-pituitary-adrenal axis responsiveness. Lower cortisol levels appear later in the progression to chronic, treatment-resistant PTSD.
To study the role of central IL-1 receptors in the effects of recombinant human IL-1 beta (IL-1 beta) on behavior and body weight, intracerebroventricular (i.c.v.) injection of the specific antagonist of IL-1 receptors, IL-1ra, was administered to mice injected intraperitoneally (i.p.) and i.c.v. with various doses of IL-1 beta. Doses of 500 ng i.p. IL-1 beta and 900 pg i.c.v. IL-1 beta induced a comparable decrease in social behavior and loss of body weight. Pretreatment with IL-1ra (1.8 micrograms/mouse, i.c.v.) blocked the effects of i.c.v. IL-1 beta (900 pg/mouse) on social behavior. i.c.v. IL-1ra (3.6 micrograms/mouse) also attenuated the effects of i.p. IL-1 beta (500 ng/mouse) on social behavior and change in body weight, suggesting that the effects of peripheral IL-1 beta are centrally mediated.
Following three series of electric footshocks (10 shocks/day), one out of three rats in most cages were brought to emit ultrasonic vocalization for several minutes after a single shock. The characteristics of shock-elicited ultrasound were pure tone pulses of a frequency between 22 and 28 kHz, with duration longer than 300 msec. The same type of ultrasound is produced by subordinate male rats during agonistic behavior. The intracerebroventricular injection of beta-endorphin, dynorphin, methionine-enkephalin or leucine-enkephalin attenuated the shock-elicited ultrasonic vocalization. Psychotropic drugs such as diazepam and chlorpromazine also attenuated the shock-elicited ultrasonic vocalization. A test utilizing ultrasonic vocalization in rodents can provide useful data for studying the psychotropic properties of neuropeptides.
A group of normally cycling women completed a battery of cognitive and motor tests during menses and during the late follicular phase of the menstrual cycle. Enhanced performance on tests of articulatory and fine motor skills was observed during the late follicular phase, while performance on tests of spatial ability was poorer at that time, compared with performance during menses. Variations in estradiol (E2) levels may be at least partially responsible for these effects.
Exercise has an anxiolytic activity and it increases the concentrations of atrial natriuretic peptide (ANP). Because ANP has an anxiolytic activity, this hormone might contribute to the anxiolytic effects of aerobic exercise. Cholecystokinin-tetrapeptide (CCK-4)-induced panic attacks were studied in 10 healthy subjects after "quiet rest" or 30 min of aerobic exercise. Plasma ANP concentrations were measured before and after exercise or quiet rest using a commercial IRMA kit. Compared to quiet rest, CCK-4-induced anxiety was reduced and plasma ANP concentrations were increased by prior exercise. This anxiolytic activity of exercise was correlated with the increase in plasma ANP concentrations. Our results suggest that besides other mechanisms, ANP might be a physiologically relevant humoral link between the heart and anxiety-related behavior contributing to the acute anxiolytic effects of exercise.
It has long been believed that stress and drug abuse are related. Studies using animal models have repeatedly demonstrated that stressed animals more readily self-administer alcohol or other drugs. Similarly, human patients consistently report in clinical interviews that stress is one reason for taking drugs. There are also studies that document neurophysiological, neuroanatomical, neurochemical, and physiological changes to animals and humans who are stressed. Many of these changes occur within biological systems that are also affected by psychoactive drugs. Early response to stress also modifies neurodevelopment in permanent ways, and these neuroadaptations occur within the same neuronal systems which comprise the drug-reward circuit. But absent are studies in humans that link early stress and modifications of neurodevelopment with increased vulnerability to drug abuse. This article provides a glimpse of research relating stress to alteration of brain functions and to drug abuse, and points to the work of others in this volume for more details. We hope this attempt to understand how early stress affects the developing brain and increases vulnerability to drug abuse will lead to a new program of research in this emerging area.
Progesterone, a steroid hormone, has been implicated in many CNS functions including reward, cognition, and neuroprotection. The goal of this study was to examine the dose-dependent effects of progesterone on cognitive performance, smoking urges, and smoking behavior in smokers. Thirty female and thirty-four male smokers participated in a double-blind, placebo-controlled study. Female smokers were in the early follicular phase of their menstrual cycle during study participation. Smokers were randomly assigned to either 200 or 400mg/day of progesterone or placebo, given in two separate doses, during clinic visit. The first 3 days of the treatment period, smokers abstained from smoking, which was verified with breath CO levels. Smokers attended an experimental session on day 4 where the number of cigarettes smoked were recorded starting 2h after the medication treatment. Progesterone treatment, 200mg/day, significantly improved cognitive performance in the Stroop and the Digit Symbol Substitution Test. Progesterone at 400mg/day was associated with reduced urges for smoking but did not change ad lib smoking behavior. These findings suggest a potential therapeutic value of progesterone for smoking cessation.
The association between hypothalamo-pituitary-adrenal (HPA) axis function and the serotonergic system could be involved in the mechanism of depression. However, neuroimaging evidence is scarce. The aim of the present study was to probe the association between dexamethasone suppression test response and serotonin transporter (SERT) availability in drug-free patients with major depressive disorder (MDD). Seventeen MDD patients (five males and twelve females) were recruited. SPECT with [(123)I] ADAM was used to measure the midbrain SERT availability, and HPA axis function was measured by the dexamethasone suppression test (DST). The association was significant when considering all participants (ρ=0.69, p=0.002). This association may have clinical implications for the treatment of MDD.
Problematic gambling is thought to be influenced by neurobiological mechanisms. However, the neuroendocrine response to gambling is largely unknown. Therefore, the effect of casino gambling on the sympathoadrenal system, the HPA-axis, and pituitary hormones were analyzed. Fourteen male problem gamblers and 15 non-problem gamblers were examined in a balanced cross-over design. In the experimental session, participants played blackjack in a casino wagering their own money. During the control session, subjects played cards for accumulation of points. Heart rate and endocrine measures were recorded at baseline, at 30, 60 and 90 min during gambling/card playing, and after the game. Heart rate and norepinephrine levels increased with the onset of blackjack in both groups, with problem gamblers showing significantly higher levels across the entire gambling session. In addition, dopamine levels were significantly higher in problem gamblers during casino gambling compared to non-problem gamblers. Cortisol levels were transiently increased with the onset of blackjack in both groups. Casino gambling as a "real life" situation induces activation of the HPA-axis and the sympathoadrenergic system, with significantly more pronounced changes in problem gamblers. These findings may contribute to a better understanding of neuroendocrine disturbances in problem gambling.
Research findings on the hypothalamic-pituitary-adrenal (HPA) axis and pediatric depression reflect a variety of methodological approaches that tap different facets of HPA-axis functions. Partly owing to the methodological heterogeneity of studies, descriptive reviews of this area have produced inconsistent conclusions. Therefore, we conducted formal meta-analyses of pertinent studies in order to advance our understanding of HPA-axis dysregulation in pediatric depression. We examined: (a) 17 published studies of HPA-axis response to the dexamethasone suppression test (DST) in depressed youth (DST; N=926) and (b) 17 studies of basal HPA-axis functioning (N=1332). We also examined descriptively studies that used corticotropin-releasing hormone (CRH) infusion, and those that used psychological probes of the HPA-axis. The global standardized mean effect size difference in HPA-axis response to the DST between depressed and non-depressed youth was 0.57, z=4.18, p<0.01. The global standardized mean difference effect size in basal HPA-axis functioning was 0.20, z=4.53, p<0.01. Age, sex, timing of sampling, dexamethasone dosage, or type of control group was not a significant source of variability for the DST or basal studies. In addition, when compared to non-depressed peers, depressed youth have a normative response to CRH infusion but an overactive response to psychological stressors. In conclusion, the HPA-axis system tends to be dysregulated in depressed youth, as evidenced by atypical responses to the DST, higher baseline cortisol values, and an overactive response to psychological stressors. This pattern of dysregulation suggests anomalies within the axis's negative feedback system and CRH production, but intact pituitary and adrenal sensitivity.
To study the effect of drugs on the hypothalamo-pituitary-gonadal (HPG) axis we compared the endocrine actions of two neuroleptics with different receptor affinity profiles-risperidone and olanzapine in male schizophrenic patients. We investigated the levels of prolactin, estradiol, testosterone, LH, FSH and testicular peptide hormone-inhibin B, and we assessed psychopathology (PANSS), sexual function (ASEX) and treatment adherence (DAI-10) in 89 male schizophrenic inpatients treated with olanzapine or risperidone administered orally. The initial and final evaluations were carried out at weeks 3 and 8 after the onset of treatment, respectively. At initial evaluation the mean serum prolactin and inhibin B levels were markedly higher, whereas testosterone level was lower in patients treated with risperidone, than in those treated with olanzapine. In 5 out of 50 subjects from risperidone group (10%) and in 1 from olanzapine group (2.6%) testosterone levels were below the lower limit (<241ng/ml), which reflected Leydig's cell impairment. In one patient receiving risperidone and in three receiving olanzapine, inhibin B level was below 80pg/ml, indicating Sertoli's cell dysfunction. At the final evaluation the mean serum prolactin level was markedly higher in patients taking risperidone, whereas their FSH levels were lower than in patients receiving olanzapine. In all investigated groups, except for the risperidone-hyperprolactinemic group inhibin B levels were negatively correlated with serum FSH. The mean LH, FSH, testosterone and estradiol levels were within the normal reference range at initial and final evaluation. The non-adherence to medications and ASEX scores were significantly higher in risperidone groups. Sexual dysfunction and medication non-adherence was not related to prolactin or gonadal hormone levels. Risperidone elicited higher PRL elevation than olanzapine. Treatment with this medication can be associated with disturbances in reproductive hormones (testosterone) and gonadotropins (FSH). The cause of olanzapine-elicited reduction of inhibin B level and the lack of negative correlation between FSH and inhibin B in patients with risperidone-induced hyperprolactinemia require further investigation. Patients receiving risperidone showed higher level of sexual dysfunction and treatment non-adherence than those treated with olanzapine.
Studies will be presented which examine the physiological and behavioral responses of squirrel monkeys and rhesus macaques following disruptions of mother-infant relationships. Reliable increases in circulating levels of plasma cortisol occur following separation of the infant from its mother. The presence of familiar conspecifics during the time of separation reduces the pituitary-adrenal response, compared to that elicited by total isolation. Visual access to the mother during separation also ameliorates the plasma cortisol response. However, when infants are separated in the presence of unfamiliar conspecifics, the physiological response is exaggerated compared to animals which are totally isolated. The behavior expressed by the infant during separation, particularly separation-induced vocalizations, is not concordant with this physiological index of affect. The rate of vocalization produced when the infant has visual access to the mother was higher than when the infant was totally isolated. However, when allowed access to familiar conspecifics, the rate of vocalization was lower than during total isolation, with no vocalization produced while the separated infant was in the unfamiliar social group. The curvilinear relationship between vocalization and the physiological index of arousal has led to a revision of the traditional concept that separation-induced infant vocalization is reflective of distress. These data support the hypothesis that vocalizations may serve as a coping response that reduces the physiological indices of arousal. Social interaction with familiar cospecifics may serve as a non-vocal coping response (e.g., proximity contact to other monkeys) which also reduces the behavioral and physiological responses to maternal separation.
When separated from groups, squirrel monkeys respond with significant increases in plasma cortisol and adrenocorticotropic hormone (ACTH). While cortisol remains elevated above pre-separation levels, significant reductions occur in ACTH. Monkeys that respond with greater increases in cortisol subsequently exhibit greater reductions in ACTH, which suggests that reductions in ACTH are mediated by corticosteroid feedback. Monkeys that respond with greater increases in cortisol also tend to exhibit greater cerebrospinal fluid levels of the dopamine metabolite HVA, but not the norepinephrine metabolite MHPG, or corticotropin-releasing factor (CRF). Attenuation of corticosteroid feedback with metyrapone results in significant increases in circulating ACTH, and in older monkeys increases plasma HVA. Similar findings in humans have been reported in clinical studies of hypercortisolism and major depression.
The focus of this manuscript is on the effects of smoking and tobacco withdrawal on the hypothalamic-pituitary axis (HPA). A variety of studies have shown that nicotine administered intravenously or through intense cigarette smoking can induce changes in hormones associated with the HPA. Administration of, and abrupt cessation from, other drugs of abuse has also been shown to affect levels of these hormones. Additionally, many of the symptoms of stress and tobacco withdrawal overlap suggesting that the hormonal changes seen during periods of stress may be observed during tobacco abstinence. These findings led to a study of the effects of tobacco withdrawal on plasma ACTH, cortisol, and prolactin levels. The results indicated tobacco cessation caused small and transient effects on plasma hormone levels which were not significantly influenced by nicotine replacement and were not related to other signs of withdrawal.
The purpose of the study was to examine demographic, immune, endocrine, stress and health characteristics of depressed mothers, measured between 4 and 6 weeks postpartum, and compare them to non-depressed mothers. The top decile (N=25) of Profile of Mood States depression scores was used to categorize mothers as depressed and these data were then compared to means of the remaining mothers (N=175) in a study of stress and immunity during the postpartum. Depressed mothers were younger, had smaller birth weight infants, and their babies experienced more illness symptoms at 4-6 weeks postpartum. Depressed mothers were less likely to be breastfeeding and had lower serum prolactin levels. Depressed mothers were more likely to smoke, to have daytime sleepiness, and more symptoms of infection than non-depressed mothers. Depressed mothers also had higher perceived stress, postpartum stress, and negative life event reports. There was evidence suggesting that depressed mothers had a downregulated hypothalamic-pituitary-adrenocortical (HPA) axis, in that salivary cortisol was lower in depressed mothers. Depressed mothers also had lower serum levels of Interferon-gamma (IFN-gamma) and a lower IFN-gamma/Interleukin-10 (IL-10) ratio in both sera and in whole blood stimulated cultures, suggesting a depressed Th1/Th2 ratio in depressed mothers. The data supports the possibility that postpartum depression may be associated with a dysregulated HPA axis and possible depressed cellular immunity.
Previous studies have shown that stress, through secretion of stress hormones, increases the consolidation of memory while it exerts negative effects on memory retrieval. Other studies show that the process of memory retrieval serves as a reactivation mechanism whereby the memory trace that is reactivated during the retrieval process is once again sensitive to modifications by pharmacological or environmental manipulations. In this study, we assessed whether exposure to stress after retrieval of neutral and emotional information modulates the immediate and long-term recall of these reactivated memory traces. Three groups of participants (total N of 47) encoded on Day 1 a movie containing neutral and emotional information. Two days later (Day 2), one group was asked to retrieve (reactivate) the story before being exposed to a stressful condition (reactivation/stress group), while the second group was asked to retrieve the story and was not exposed to a stressful condition (reactivation/no stress group). A third group did not recall the story but was exposed to a stressful condition (no reactivation/stress group). All participants were asked to recall the story immediately after exposure to the stress/no stress condition (immediate recall) as well as 5 days later (delayed recall). Results show that immediate recall of emotional information was significantly increased in the reactivation/stress group when compared to the reactivation/no stress group while no effect of stress on reactivated neutral memories was found. Moreover, evidence suggests that the enhanced memory trace is maintained across time, suggesting a potential long-lasting effect of stress on reactivated memory traces. We also found that the enhanced emotional memory trace observed in the reactivation/stress group was not present in the no reactivation/stress group, showing that stress has the capacity to enhance memory only when the memory trace is acutely reactivated before exposure to stress. Altogether, these results suggest that stress differentially modulates reactivated emotional and neutral memory traces and that this effect is long-lasting. These results have important implications for the potential influence of acute stress on reactivated memories in individuals exposed to traumatic events.
The metabolic-endocrine state of diabetes mellitus affects the brain and behavior of diabetic animals. Feeding, paradoxical sleep, analgesia, submissive behavior, and avoidance behavior, are generally increased in diabetic compared with nondiabetic rodents. In contrast, sexual behavior, aggressive behavior and sensitivity to the behavioral effects of amphetamine are decreased in diabetic rodents. This review examines behavioral changes in diabetes mellitus within the context of known disease-linked alterations in hypothalamo-pituitary relationships and brain monoamine metabolism.
Stress can affect the establishment and maintenance of social hierarchies. In the present study, we investigated the role of increasing corticosterone levels before or just after a first social encounter between two rats of a dyad in the establishment and the long-term maintenance of a social hierarchy. We show that pre-social encounter corticosterone treatment does not affect the outcome of the hierarchy during a first encounter, but induces a long-term memory for the hierarchy when the corticosterone-injected rat becomes dominant during the encounter, but not when it becomes subordinate. Post-social encounter corticosterone leads to a long-term maintenance of the hierarchy only when the subordinate rat of the dyad is injected with corticosterone. This corticosterone effect mimics previously reported actions of stress on the same model and, hence, implicates glucocorticoids in the consolidation of the memory for a recently established hierarchy.
Developmental language and learning disabilities in children can take many different forms and can result from a variety of causes. Research to date has focused primarily on specific disabilities in learning, which are characterized by a significant delay or disorder in one aspect of learning against a background of otherwise normal development. Learning disabilities affecting language and/or reading acquisition (developmental dysphasia and dyslexia) have been studied most thoroughly. Verbal learning disabilities occur more frequently in boys than in girls, and there is a higher than expected incidence of left-handedness among affected children. Although there are many reasons why a child may have delayed or disordered language development, differential diagnosis of specific developmental language or reading disorders calls for ruling out mental retardation, peripheral auditory or visual dysfunction, autism, frank neurological impairments such as hemiplegia or seizure disorder, and severe social deprivation or lack of educational opportunity. The typical profile of a developmentally dysphasic or dyslexic child is one who shows a marked discrepancy between nonverbal (performance) IQ and verbal IQ, with a history of delayed or disordered speech, language and/or reading development. Such a child usually performs quite normally on visual spatial tasks, while demonstrating severe deficits in tasks of auditory temporal processing, motor sequencing, phonological processing and memory, language, reading and spelling. This characteristic neuropsychological profile may suggest left hemisphere dysfunction or a failure to develop normal cerebral lateralization. The etiology of these developmental learning disorders is unknown, but there is evidence of familial aggregation, indicating a potential genetic basis. Although these children respond to remediation, longitudinal studies have shown that the symptoms often persist into adulthood (see Tallal, 1988, for a more detailed discussion).
To investigate the longitudinal relationship between pituitary gland volume (PGV) and parameters of hypothalamic-pituitary-adrenal axis (HPAA) functioning during adolescence. Participants were 49 adolescents (19 girls and 30 boys) selected from a larger longitudinal, population-based study of adolescent development. Assessments were conducted at three time points (S1, S2 and S3). MRI sessions were at S1 (age: M=12.62, SD=0.45 years) and S3 (M=16.48, SD=0.53 years) and multiple assessments of salivary cortisol were undertaken at S2 (M=15.51, SD=0.35 years). PGV was measured via previously validated manual tracing methods, and the cortisol awakening response (CAR) and diurnal slope (DSL) were used as indices of HPAA functioning. A significant sex-linked interaction was found for PGV at S1 predicting both CAR (p=0.025) and DSL (p=0.009) at S2. Specifically, PGV at S1 significantly predicted CAR (p=0.033) and DSL (p=0.010) in boys only, with no significant results found for girls. Neither CAR nor DSL at S2 predicted growth of PGV from S1 to S3. PGV in early adolescence predicted HPAA functioning in mid-adolescent boys but not in girls. The results suggest a significant influence of sex-specific development on the relationship between PGV and HPAA activity and reactivity. The findings have potential implications for understanding and interpreting sex-linked and stress related clinical disorders that emerge during mid-to-late adolescence.
The 24 hr profiles of melatonin and cortisol in serum, morning levels of ACTH in plasma, and the dexamethasone suppression test (DST) were investigated in 32 acutely ill patients with a RDC diagnosis of major depressive disorder, 24 patients with a history of longlasting unipolar or bipolar major depressive disorder studied in remission, and 33 healthy subjects. A significant decrease in maximum nocturnal melatonin level (MTmax) was found in the acutely ill depressed patients with abnormal DST compared to both those with normal DSTs and the healthy subjects. The MTmax levels were unaltered when these patients were reinvestigated in remission. A decrease of MTmax was also seen in the group of unipolar and bipolar patients studied in remission. Low nocturnal melatonin is proposed to be a trait marker for major depressive disorder and depressive states with abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis.
We tested the hypothesis that changes in endogenous neuroactive steroids acting as positive allosteric modulators of gamma-aminobutyric acid (GABA)(A) receptors may be related to the menopause-associated mood alterations. The study sample consisted of twenty five drug-free menopausal women, 1-3 years since the onset of menopause, homogeneous for age and body mass index (BMI) and without personal history of psychiatric, metabolic or endocrine disorders. Depression and anxiety-related symptoms were assessed with the Zung Self-administered Depression Scale (ZSDS) and the Cornell's Dysthymia Rating Scale (CDRS). The cut-off value predicted by the ZSDS index defined two groups of women (asymptomatic [35.5+/-4.6, n=12] and symptomatic [60.8+/-7.9, n=13]), that were also significantly different according to the CDRS scores (10.6+/-3.4 and 31.5+/-12, respectively, P<0.05). Upon evaluation of the scores relative to the anxiety factor of the CDRS (items 11-15) the symptomatic, but not the asymptomatic, group showed a moderate level of anxiety. The plasma concentrations of several neuroactive steroids were measured, after extraction and HPLC purification, by radioimmunoassay with specific antisera. Only dehydroepiandrosterone and its metabolite 5alpha-androstane-3alpha,17betadiol (3alpha-ADIOL), a positive allosteric modulator of GABA(A) receptors, were significantly (P<0.05 and P<0.005) higher (+110% and +64%, respectively) in the asymptomatic group. A highly significant and negative correlation (r=-0.672, P=0.003) was found between the plasma 3alpha-ADIOL concentrations and the scores of the anxiety factor of the CDRS. These data suggest that endogenous 3alpha-ADIOL modulates the central GABAergic tone and that higher 3alpha-ADIOL concentrations could have a role in preventing the expression of anxiety in the asymptomatic women.
Cogent evidence points to the involvement of neurosteroids in the regulation of dopamine (DA) neurotransmission and signaling, yet the neurobiological bases of this link remain poorly understood. We previously showed that inhibition of 5α-reductase (5αR), a key neurosteroidogenic enzyme, attenuates the sensorimotor gating deficits induced by DA receptor activation, as measured by the prepulse inhibition (PPI) of the acoustic startle reflex. To extend these findings, the present study was aimed at the assessment of the role of other key neurosteroidogenic enzymes in PPI, such as 17α-hydroxylase/C17,20 lyase (CYP17A1), 3α- and 3β-hydroxysteroid dehydrogenase (HSD), in Sprague-Dawley rats. The PPI deficits induced by the DAergic non-selective agonist apomorphine (APO, 0.25mg/kg, SC) were dose-dependently attenuated by the selective CYP17A1 inhibitor abiraterone (ABI, 10-50mg/kg, IP) in a fashion akin to that of the 5αR inhibitor finasteride (FIN, 100mg/kg, IP). These systemic effects were reproduced by intracerebroventricular injection of ABI (1μg/1μl), suggesting the involvement of brain CYP17A1 in PPI regulation. Conversely, the PPI disruption induced by APO was not significantly affected by the 3α- and 3β-HSD inhibitors indomethacin and trilostane. Given that CYP17A1 catalyzes androgen synthesis, we also tested the impact on PPI of the androgen receptor (AR) antagonist flutamide (10mg/kg, IP). However, this agent failed to reverse APO-induced PPI deficits; furthermore, AR endogenous ligands testosterone and dihydrotestosterone failed to disrupt PPI. Collectively, these data highlight CYP17A1 as a novel target for antipsychotic-like action, and suggest that the DAergic regulation of PPI is modulated by androgenic neurosteroids, through AR-unrelated mechanisms.
(1) In castrated male guinea pigs protracted infusion to steady state levels of 3H-testosterone (T) either alone or in combination with 14C-dihydrotestosterone (DHT) or 14C-estradiol-17β (E) was used to estimate uptake and retention of these steroids from the blood by the anterior pituitary (AP), posterior pituitary (PP), medial basal hypothalamus (MBH), cerebellum (CB) and cerebral cortex (CC). In addition, the amount of 3H-T converted by these various tissues to 3H-DHT and 3H-E was measured. (2) When 3H-T was infused alone, all tissues studied took up and retained the steroid in higher concentrations than blood. The relative order from highest to lowest concentration was as follows: AP>PP>MBH>CB>CC. When 3H-T was infused simultaneously with either 14C-DHT or 14C-E, the 14C-androgen interfered with 3H-T uptake in both the AP and MBH (not in the other tissues); whereas, the 14C-estrogen interfered with 3H-T uptake only in the AP. (3) 14C-DHT and 14C-E were sequestered by those tissues examined. Intertissue differences were not evident for 14C-DHT levels; in contrast, 14C-E was substantially more concentrated in the AP, PP and MBH. (4) Intratissue conversion of T to DHT and T to E were noted. For those tissues showing the greatest affinity for T (AP, PP and MBH), the percentage of DHT derived by in situ metabolic conversion was consistently greater (81–15%) than the percentage of E (12–0%) similarly derived. For those tissues showing a low affinity for T (CB and CC), the opposite was the case. (5) The brain metabolized (extracted) 28% of both incoming T and DHT and 35% of E. (6) Metabolic clearance rates of T, DHT and E were 54.2, 71.1 and 33.7 ml/min × kg−1, respectively. (7) The results indicate extensive brain metabolism of the three hormones examined and also suggest that there is more than one population of androgen receptor. The localization of active T and E uptake and rapid metabolism of T to DHT in neuroendocrine areas reinforces the belief that hormonal actions depend upon these events in this species.
Mature male mice of proven fertility were administered chronic oral doses of anastrozole, a potent aromatase inhibitor, and also given a low-phytoestrogen diet. Urine was taken non-invasively from such males and from untreated control males and assayed for 17beta-estradiol and testosterone via ELISA procedures. After 8 weeks of drug or vehicle administration, urinary 17beta-estradiol declined to significantly lower levels in anastrozole-treated males than in non-treated males, whereas testosterone levels were comparable in the two groups. Inseminated females were exposed to drug-treated, vehicle-treated, or no males during days 1-6 of gestation, around intrauterine implantation of fertilized ova. Females exposed to vehicle-treated males produced fewer litters than did those kept in isolation. Females exposed to anastrozole-treated males produced significantly more litters than did those exposed to vehicle-treated males. These data support the notion that male excretions of estrogens may in part mediate novel-male-induced pregnancy disruptions, although other influences of aromatization on behaviour and metabolism remain possibilities.
(1) One-half hour after the intravenous injection of [3H]testosterone, basal brain cell nuclei isolated from castrated male rats contained more radioactivity with the thin layer chromatography mobility of estradiol-17β and dihydrotestosterone (DHT) than nuclei from female rats. (2) The sex differences in the subcellular localization of [3H]DHT and [3H]estradiol-17β were not reflected in the ratio of the nuclear to whole homogenate radioactivity. (3) In the basal brain, estradiol-17β was the only metabolite examined that showed more DPM/mg protein in the nuclear fraction than in the whole homogenate. (4) In the basal brain and pituitary, unlabeled DHT was more effective than testosterone in blocking the nuclear localization of [3H]testosterone and [3H]DHT. (5) Unlabeled estradiol-17β only blocked the nuclear concentration of [3H]estradiol-17β and not [3H]testosterone or [3H]DHT.
Ovariectomy and subchronic estradiol-17 beta cause a down-regulation of dopamine D1 and, to a lesser extent, D2 receptors in rat striatum. An intracellular mechanism mediates the DA receptor down-regulation, as various estrogens do not interact with membrane-bound DA receptors in vitro. A common denominator, e.g. enhanced DA turnover, is suggested to mediate the estradiol-induced DA receptor down-regulation. Ovarian factors other than estradiol are additionally proposed to be involved in the regulation of striatal DA receptors.
The present experiments sought the effect of chronic treatment with 17β-estradiol on striatal dopaminergic activity and the Akt/GSK3 signaling pathway in the brain of monkeys. Eight female monkeys (Macacca fascicularis) were ovariectomized (OVX) and a month later, half received a month treatment with 17β-estradiol and the other with vehicle. The DA transporter (DAT) was measured by autoradiography with [(125)I]RTI-121 and the vesicular DA transporter (VMAT(2)) with [(3)H]TBZ-OH at three rostro-caudal levels (anterior, middle and posterior) of the caudate nucleus and putamen subdivided in their lateral/medial, ventral/dorsal sub-regions. Specific binding to DAT was increased in all sub-regions of the caudate nucleus and the putamen of 17β-estradiol-treated compared to vehicle-treated monkeys whereas specific binding to VMAT(2) remained unchanged. We measured by Western blot the phosphorylated forms of Akt at serine 473 and threonine 308, GSK3β at serine 9 and tyrosine 216 and GSK3α at serine 21 in anterior, middle and posterior caudate nucleus and putamen. 17β-Estradiol treatment increased in all the caudate nucleus and putamen pAkt (Ser473)/βIII-tubulin, pGSK3β (Ser9)/βIII-tubulin and in putamen Akt/βIII-tubulin compared to vehicle-treated monkeys. In anterior and middle putamen, pAkt (Thr308)/βIII-tubulin was also increased in monkeys treated with 17β-estradiol. pGSK3β (Tyr216)/βIII-tubulin and pGSK3α (Ser21)/βIII-tubulin remained unchanged by the 17β-estradiol treatment. These results suggest that 17β-estradiol activates striatal DA neurotransmission in primates as reflected with increased DAT specific binding and downstream activation of Akt/GSK3 signaling. This supports a beneficial role of a chronic treatment with 17β-estradiol by increasing the activity of signaling pathways implicated in cell survival.
(1) Evidence has been presented, based on quantitative microfluorimetric estimations of dopamine (DA) and noradrenaline (NA) levels and turnover, and on radioimmunological measurements of serum luteinizing hormone (LH), and follicle-stimulating hormone (FSH) and prolactin levels, that the central inhibitory feedback action of estradiol on LH secretion mainly involves a marked increase in DA turnover of the lateral palisade zone (LPZ) of the median eminence and also involves a reduction of NA turnover, mainly located in the medial preoptic area (MPOA) and in the subependymal layer (SEL). (2) The mechanism for these changes in catecholamine (CA) turnover is discussed. The possibility is favored that they involve the stimulation of central cytosol estrogen receptors which may even be located in the arcuate DA and possibly reticular NA cell bodies themselves. (3) The marked and long-lasting hypersecretion of prolactin caused by estrogen could be involved in mediating the sustained increase of DA turnover in the median eminence and the sustained reduction of NA turnover. (4) The central facilitatory feedback action of estrogen, on the other hand, may be mainly responsible for the sharp increase of NA turnover in the MPOA and SEL and also the associated reduction of DA turnover in the LPZ in the critical period of both adult cyclic rats and of immature female rats treated with PMS. (5) We take the view that these latter NA and DA turnover changes take precedence over cytosol estrogen receptors, which previous evidence indicates (see Sawyer, 1975) are located in preoptic and amygdaloid regions. (These estradiol concentrating neurons then directly and/or indirectly make connections with the NA and DA pathways). (6) FSH secretion is not controlled by DA and NA pathways. (7) The hypothesis given above is based on the assumption that different estradiol concentrating neurons are involved in the central inhibitory and facilitatory feedback action of estradiol and that the estrogen receptors of these respective neurons have differences which allow their differential activation, the inhibitory feedback leading mainly to a marked increase in the ratio DA activity/NA activity in the median eminence, whereas the facilitatory feedback causes a marked reduction of this ratio.
Allele and genotype distributions in WTCCC BD and PGC-BD cases and controls. 
TSPO mediated transport of cholesterol into the mitochondrion is a necessary step in steroid synthesis. The rs6971 polymorphism in the TSPO gene causes an amino acid substitution (Ala147Thr) within the transmembrane domain where the cholesterol-binding pocket is located, and has been shown to affect the steroidogenic pathway. We report a nominal association between this TSPO polymorphism and the diagnosis of Bipolar Disorder in both the genome-wide dataset of the Wellcome Trust Case-Control Consortium and the Psychiatric Genome-Wide Association Study Consortium Bipolar Disorder group (OR=1.11, p=0.007; OR=1.10, p=0.011, respectively). We propose that the amino acid substitution affects hypothalamic-pituitary-adrenal (HPA) regulation, and hence may predispose to Bipolar Disorder. This supports the hypothesis that HPA dysregulation has a causal role in Bipolar Disorder, and is not just a consequence of the disease.
Stress and stress-related health impairments are major problems in human life and elucidating the biological pathways linking stress and disease is of substantial importance. However, the identification of mechanisms underlying a dysregulation of major components of the stress response system is, particularly in humans, a very challenging task. Salivary cortisol responses to diverse acute challenge paradigms show large intra- and interindividual variability. In order to uncover mechanisms mediating stress-related disorders and to potentially develop new therapeutic strategies, an extensive phenotyping of HPA axis stress responses is essential. Such a research agenda depends on substantial knowledge of moderating and intervening variables that affect cortisol responses to different stressors and stimuli. The aim of this report is, therefore, to provide a comprehensive summary of important determinants of, in particular, human salivary cortisol responses to different kinds of laboratory stimuli including acute psychosocial stress as well as pharmacological provocation procedures. This overview demonstrates the role of age and gender, endogenous and exogenous sex steroid levels, pregnancy, lactation and breast-feeding, smoking, coffee and alcohol consumption as well as dietary energy supply in salivary cortisol responses to acute stress. Furthermore, it briefly summarizes current knowledge of the role of genetic factors and methodological issues in terms of habituation to repeated psychosocial stress exposures and time of testing as well as psychological factors, that have been shown to be associated with salivary cortisol responses like early life experiences, social factors, psychological interventions, personality as well as acute subjective-psychological stress responses and finally states of chronic stress and psychopathology.
Vasopressin and oxytocin seem to be involved in the processes of learning and memory in animals and probably in man. These peptides appear to have opposite effects in that vasopressin improves memory processes and oxytocin produces amnestic effects. We measured these neuropeptides in the cerebrospinal fluid of schizophrenic patients with and without neuroleptic treatment, psychiatrically healthy controls and drug-free patients before and after three weeks' neuroleptic treatment. There were no significant differences in vasopressin concentrations between schizophrenics and controls. No influence of neuroleptic treatment on vasopressin concentrations was detected. In contrast, concentrations of oxytocin were increased in all schizophrenic patients and were higher in those receiving neuroleptic treatment. In addition, oxytocin concentrations increased after three weeks' neuroleptic treatment. Drug-induced increase of oxytocin concentrations may be of significance in the clinically observed amnestic syndromes and debilitation in schizophrenics treated with neuroleptics.
Estradiol induces coordinated modifications in the extension of glial and neuronal processes in the arcuate nucleus of the hypothalamus of adult female rats. This hormonal effect results in natural fluctuations in the ensheathing of arcuate neurons by glial processes and these glial changes are linked to a remodelling of inhibitory GABAergic synapses during the estrous cycle. Hormonally induced glial and synaptic changes appear to be dependent on specific recognition or adhesion molecules on the neuronal and/or glial membranes.
The current study investigated the associations between thyroid stimulating hormone (TSH), free thyroxine (T(4)) and cognitive ability (general ability, memory and processing speed), in a large age homogenous sample (n=659) of generally healthy euthyroid older adults. Associations were considered both at baseline (mean age wave 1=69.5 years; SD=0.8 years) and approximately 3 years later (mean age wave 2=72.5 years; SD=0.7 years). Results indicated mean level decreases across waves in both TSH (t=10.99, p<0.001) and T(4) (t=34.55, p<0.001). There were no significant associations between TSH and T(4) with any of the cognitive variables at either wave. There was no suggestion of non-linear associations. The lack of associations supports suggestions that the effects of thyroid hormones on cognition may be restricted to older individuals above a given threshold, and/or those with levels of thyroid hormones within the range defining clinical thyroid disorder.
During an immune challenge it has been suggested that responding cells secrete cytokines which then stimulate the release of glucocorticoids. Glucocorticoids, in turn, are believed to bind to their receptors in target immune tissues and provide feedback inhibition on evolving immune responses. The foundations for this hypothesis have been drawn primarily from studies on animal models of autoimmune and/or inflammatory processes, and the relevance of these glucocorticoid-immune interactions to viral infections has not been extensively examined. Accordingly, we infected mice with lymphocytic choriomeningitis virus (LCMV) and measured plasma corticosterone and cytosolic glucocorticoid receptor (GR) binding at multiple time points throughout the day and throughout infection (days 3, 5, 7 and 10 post infection). Despite a vigorous immune response to this virus, LCMV infection was associated with minimal and transient increases in corticosterone secretion. Interestingly, however, significant decreases in cytosolic GR were found in immune tissues. Receptor decreases were characterized by a significant decrease in GR binding during the diurnal rise in corticosterone in the spleen and thymus of infected but not uninfected animals on days 5-10 post infection. In addition, in the morning on these days, GR binding in the spleen of infected mice was decreased compared to uninfected control mice. Following an acute injection of corticosterone on day 7 post infection, LCMV-infected animals exhibited a significantly greater decrease in splenic GR binding than uninfected control mice, suggesting an increased sensitivity to corticosterone in infected animals. No changes were found in the affinity (Kd) of the GR during infection, nor was there evidence of an infection-associated decrease in plasma corticosteroid binding globulin. The appearance of significant GR changes in the spleen and thymus, in the absence of significant elevations in corticosterone or decreases in its binding protein, suggests that cytokines and/or other factors produced within the immune tissues during infection either directly influenced GR number and/or function or influenced the local availability of corticosterone. Taken together, the results indicate that interactions between the neuroendocrine and immune systems can be modified at the level of the GR in the context of an ongoing immune response such as during a viral infection.
This meeting was the sixth consecutive Nicotine Round Table Satellite Meeting which was held in Washington, DC, on 15 November, 1996; previous meetings are presented in Table I. The overall objective of these meetings was to bring together scientists and clinicians as a means of developing a dialogue concerning the basic mechanisms of nicotine action and the effects of nicotine on the whole organism. The specific topic of this meeting was chosen because of the potent effects of nicotine on the hypothalamic-pituitary-axis (HPA), and newer concepts indicating that the immune system and the HPA are connected via a variety of neuroendocrine and neurotransmitter elements. Whereas the HPA appears to play a unique role in adapting to internal and external stressors, the immune system appears to act as a forward scout which provides information important to the HPA. This Satellite Meeting evaluated the effects of nicotine from three points of view: (1) the effects of nicotine on HPA function; (2) the effects of the HPA on the pharmacological effects of nicotine; and (3) the effects of nicotine on immune function. This specific presentation will provide an overview of the findings of the meeting and will discuss several of the overriding issues in this area of nicotine research.
Although evidence seems to indicate favorable effects of hormone replacement therapy (HRT) on cognitive functions and mood in elderly healthy and demented women, some questions remain. For instance, the nature of the long term effect of HRT, e.g. in preventing cognitive decline is still unclear. In this respect, the addition of progestagens in combined HRT has been mentioned to oppose some of the beneficial effects of estrogens. The present paper aims to illuminate these questions and presents two studies. In the first study, the long term effects of combined HRT in healthy postmenopausal women was investigated using a parallel groups (HRT-users vs. controls) design. HRT subjects were always tested during the estrogen-progestagen phase. Results indicated that after 6 and 12 months, women in the HRT-treatment group had higher scores on several indicators of the subjective feeling of well being (sleep, physical and psychological complaints) than matched controls, although at baseline both groups were not severely impaired. Effects of HRT on memory functions were seen when HRT treated subjects were compared with their own baseline functioning, but not when compared with controls. Hence, the addition of progestagen did not oppose the effects of estrogens on subjective feelings of well being or on memory. Our second (case-control) study involved women of middle-age who were unaware of the purpose of the experiment. No positive effects of HRT use on subjective scales of well being or on memory were found. However, women with HRT were faster on basic sensorimotor speed tasks as compared with controls. It should be kept in mind that double blind testing in an experimental study is difficult due to withdrawal bleeding and the reduction of flushes. Expectancy effects may have confounded the results of the first study. However, our findings indicate that the use of a particular design and type of memory test can explain the controversial results of studies into the effect of HRT on cognitive function. Furthermore, it was concluded that HRT has a global activating, instead of specific direct effect on cognitive functions.
Top-cited authors
Dirk Hellhammer
  • Universität Trier
Clemens Kirschbaum
  • Technische Universität Dresden
Ulrike Ehlert
  • University of Zurich
Stefan Wüst
  • Universität Regensburg
Clemens Kirschbaum
  • Technische Universität Dresden