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F Holsboer

Publications and source records attributed to F Holsboer.

At least 91 records · Page 5Linked to original sources
PubMed2000

Behavioral and endocrine response to cholecystokinin tetrapeptide in patients with posttraumatic stress disorder.

BACKGROUND: Given the relationship between posttraumatic stress disorder (PTSD) and panic, it was of interest to examine whether panic provoking agents affect PTSD symptoms. We therefore investigated the behavioral and endocrine response of PTSD patients to the panicogen cholecystokinin tetrapeptide (CCK-4). METHODS: Eight patients with PTSD (DSM-IV) received 50 micrograms CCK-4 intravenously in a placebo-controlled, double-blind balanced design. Provocation of panic, anxiety, and flashbacks was assessed. Plasma adrenocorticotropin (ACTH) and cortisol levels after CCK-4 were measured and compared to healthy subjects matched for age, gender, and provoked symptoms. RESULTS: Despite significant effects of CCK-4 on anxiety and panic symptoms, no significant provocation of flashbacks emerged. CCK-4-induced panic symptoms showed an inverse correlation to trait dissociation. The ACTH response after CCK-4 was significantly lower in PTSD patients than in controls. Cortisol was similarly increased in both groups after CCK-4, but PTSD patients showed a more rapid decrease of stimulated cortisol concentrations. CONCLUSIONS: Panic symptoms or heightened anxiety are not necessarily conditioned stimuli for the provocation of posttraumatic flashbacks. Further studies in PTSD with different panicogens should be controlled for the potential interference of trait dissociation. Our hormone data show further evidence for a corticotropin-releasing hormone (CRH) overdrive and enhanced negative glucocorticoid feedback in PTSD patients.

Adrenocorticotropic Hormone↗
PubMed2000

New mode of hypothalamic-pituitary-adrenocortical axis regulation: significance for stress-related disorders.

Two types of corticosteroid receptors have been identified in the brain and pituitary that play an important role in the regulation of the hypothalamic-pituitary-adrenocortical (HPA) axis. These glucocorticoid hormone binding receptors are the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). Evidently, a tight control of the concentration and function of these receptors is of prime importance for maintaining and regaining homeostasis after stressful challenges. Here, we describe a novel mechanism revealing a rapid upsurge in MR density in the hippocampus (a limbic structure highly involved in HPA axis regulation) after an acute psychologically stressful challenge. This rise in MR is accompanied by a stronger MR-mediated inhibitory control of the HPA axis. Thus, an acute stressful experience results in a reorganization of the HPA axis involving a principal role of the hippocampal MR. This novel mechanism may be of significance for increasing our understanding of the etiology of stress-related disorders.

Animals↗
PubMed2000

Increased activity of the hypothalamus-pituitary-adrenal system after treatment with the mineralocorticoid receptor antagonist spironolactone.

The hippocampal mineralocorticoid receptor (MR) is critical for the regulation of the basal activity of the hypothalamus-pituitary-adrenocortical (HPA) system. It has been hypothesized that reduced capacity of the hippocampal MR is involved in the HPA-system dysregulation found in depression and aging. We applied the combined dexamethasone suppression/corticotropin releasing hormone stimulation (DEX/CRH) test to six healthy young females both before and after 12 days of treatment with the MR antagonist spironolactone to assess HPA regulation. Treatment with spironolactone caused a significant increase in post-dexamethasone cortisol concentrations (75.1+/-56.7 vs. 36.6+/-24.6 nmol/l, p<0.05). Furthermore, we observed a significant rise in peak cortisol concentration after additional human CRH (hCRH) application (223. 6+/-139.1 vs. 126.7+/-73.3 nmol/l, p<0.02). There was no change in ACTH plasma concentrations. We thus conclude that (1) the MR antagonist spironolactone affects HPA system regulation as reflected in the DEX/CRH test and (2) these findings are in accordance with the assumption that MR dysfunction may underlie HPA-system dysfunction in depression and/or aging.

Adrenal Glands↗
PubMed2000

The corticosteroid receptor hypothesis of depression.

Signs and symptoms that are characteristic for depression include changes in the setpoint of the hypothalamic-pituitary-adrenocortical (HPA) system, which in the majority of these patients result in altered regulation of corticotropin (ACTH) and cortisol secretory activity. More refined analysis of the HPA system revealed that corticosteroid receptor (CR) signaling is impaired in major depression, resulting among other changes, in increased production and secretion of corticotropin-releasing hormone (CRH, also frequently abbreviated CRF) in various brain regions postulated to be involved in the causality of depression. This article summarizes the clinical and preclinical data, supporting the concept that impaired CR signaling is a key mechanism in the pathogenesis of depression. Mouse genetics, allowing for selective inactivation of genes relevant for HPA regulation and molecular pharmacology, dissecting the intracellular cascade of CR signaling, are the most promising future research fields, suited for identifying genes predisposing to depression. Focusing on these two research lines may also allow to gain insight into understanding how current antidepressants work and further, how more specific targets for future antidepressant drugs can be identified.

Animals↗
PubMed2000

Penetration of amitriptyline, but not of fluoxetine, into brain is enhanced in mice with blood-brain barrier deficiency due to mdr1a P-glycoprotein gene disruption.

Mice with a genetic disruption (knockout) of the multiple drug resistance (Mdr1a) gene were used to examine the effect of the absence of the drug-transporting P-glycoprotein at the blood-brain barrier on the uptake of amitriptyline (AMI) and fluoxetine (FLU) and their metabolites into the brain. One hour after intraperitoneal injection of AMI or FLU, knockout (-/-) and wild-type (+/+) mice were sacrificed and drug concentrations of brain, kidney, liver, testis, and plasma were measured. The plasma concentrations of the AMI metabolites and the brain:spleen ratios of AMI, nortriptyline (NOR), 10-OH-AMI and 10-OH-NOR were significantly higher in the -/- mice, demonstrating that AMI and its metabolites are substrates of the P-glycoprotein and that mdr1a activity at the level of the blood-brain barrier reduces the penetration of these substances into the brain. In contrast, tissue distributions of FLU and its metabolites among the various tissues tested were indistinguishable between groups. The herein reported differences in brain penetration of antidepressant drugs depending on the presence of the mdr1a gene may offer an explanation for differences in the treatment response at a given plasma concentration. Moreover, individual differences in mdr1 gene activity may account for variable response patterns at different episodes and development of therapy resistance.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2000

Increased ACTH concentrations associated with cholecystokinin tetrapeptide-induced panic attacks in patients with panic disorder.

Preclinical findings on the role of corticotropin releasing hormone (CRH) in stress and anxiety, on the interaction of CRH and cholecystokinin (CCK) in modulating anxiety, as well as the blunted corticotropin (ACTH) response to CRH in panic disorder suggest that CRH may play a role in panic disorder. To further characterize the role of the hypothalamic-pituitary-adrenocortical (HPA) system in panic disorder, we compared patients with and without CCK tetrapeptide (CCK-4) induced panic attacks. Twenty-four patients with panic disorder were given injections of CCK-4 (25 micrograms). Panic attacks, psychopathological changes, as well as ACTH and cortisol secretion were recorded. Fifteen of the 24 patients experienced a panic attack after CCK-4. ACTH secretion was significantly higher in the patients with CCK-4-induced panic attacks than in those without such attacks. The patients without CCK-4-induced attacks had a brief but less pronounced increase in ACTH concentrations. Cortisol concentrations were not significantly increased after CCK-4 administration. The increased ACTH concentrations suggest that the activation of the HPA system in CCK-4-induced panic attacks plays a physiological role. CRH may be involved in experimentally-occurring and perhaps in naturally-occurring panic attacks as well.

Adrenocorticotropic Hormone↗
PubMed2000

Genome-wide, large-scale production of mutant mice by ENU mutagenesis.

In the post-genome era, the mouse will have a major role as a model system for functional genome analysis. This requires a large number of mutants similar to the collections available from other model organisms such as Drosophila melanogaster and Caenorhabditis elegans. Here we report on a systematic, genome-wide, mutagenesis screen in mice. As part of the German Human Genome Project, we have undertaken a large-scale ENU-mutagenesis screen for dominant mutations and a limited screen for recessive mutations. In screening over 14,000 mice for a large number of clinically relevant parameters, we recovered 182 mouse mutants for a variety of phenotypes. In addition, 247 variant mouse mutants are currently in genetic confirmation testing and will result in additional new mutant lines. This mutagenesis screen, along with the screen described in the accompanying paper, leads to a significant increase in the number of mouse models available to the scientific community. Our mutant lines are freely accessible to non-commercial users (for information, see http://www.gsf.de/ieg/groups/enu-mouse.html).

Animals↗
PubMed2000

Differential induction of NF-kappaB activity and neural cell death by antidepressants in vitro.

Tricyclic antidepressants and selective serotonin reuptake inhibitors are here shown to induce cell death in a neural cell line. The exposure to these drugs led to increased generation of reactive oxygen species and a concomitant reduction of intracellular glutathione levels. Furthermore, these antidepressants induced DNA fragmentation and increased the transcriptional and DNA-binding activity of NF-kappaB. In contrast, treatment with type A and B monoamine oxidase inhibitors did not induce changes in NF-kappaB activity and did not exert a detrimental influence on cell viability. These results indicate that some antidepressant drugs may cause both oxidative stress and changes in cellular antioxidative capacity, resulting in altered NF-kappaB activity and, ultimately, cell death.

Animals↗
PubMed2000

Brain oxytocin inhibits basal and stress-induced activity of the hypothalamo-pituitary-adrenal axis in male and female rats: partial action within the paraventricular nucleus.

Oxytocin is a classic reproductive neuropeptide in the female mammal, but its functions in the brain of the male have been less well studied. As stress induces intracerebral oxytocin release independently of gender, we postulated that central oxytocin may play a role in the control of stress responses. In both male and virgin female rats, oxytocin receptor blockade in the brain by intracerebral infusion of a selective oxytocin antagonist (des Gly-NH2 d(CH2)5 [Tyr(Me)2, Thr4] OVT; 0.75 microgram/5 microliter increased the activity of the hypothalamo-pituitary-adrenal (HPA) axis as indicated by a significantly enhanced basal and stress-induced (exposure to the elevated plus-maze, forced swimming) secretion of corticotropin (ACTH) and corticosterone into blood. The anxiety-related behaviour on the plus-maze was not altered by the antagonist in either males or females. Infusion of the oxytocin antagonist into the hypothalamic paraventricular nucleus by reversed microdialysis resulted in a significant increase in basal release of ACTH in both male and virgin female rats. These results demonstrate a novel, gender-independent physiological function of endogenous brain oxytocin in the regulation of neuroendocrine stress responses. Under basal conditions, the inhibition of the HPA axis occurs, at least in part, within the paraventricular nucleus.

Adrenal Glands↗
PubMed2000

Ageing alters intrahypothalamic release patterns of vasopressin and oxytocin in rats.

The ageing process has been shown to have a profound impact on the hypothalamo-neurohypophysial system (HNS) and the hypothalamo-pituitary-adrenocortical (HPA) axis in humans as well as in rodents. Therefore, in this study, the intracerebral and peripheral release patterns of both vasopressin and oxytocin have been studied in aged male Wistar rats under basal conditions and in response to ethologically relevant stressors, using intracerebral microdialysis and chronic blood sampling techniques, respectively. Approximately a twofold higher basal release of arginine vasopressin (AVP) within the hypothalamic paraventricular nucleus (PVN), but not within the supraoptic nucleus (SON), was found in aged rats, whereas basal oxytocin (OXT) release did not differ in comparison with young rats. With increasing age the rise in intra-PVN release of both AVP and OXT was blunted in response to forced swimming. In contrast, the intra-SON release of AVP was unrelated to age. Simultaneously recorded basal secretion of both AVP and OXT from the neurohypophysis into blood was increased in aged rats, with a blunted OXT response to swim stress. Opposed to that, plasma AVP levels remained unchanged in both groups. Basal plasma levels of corticotropin (ACTH) and corticosterone were elevated in aged rats, whereas stress-elicited ACTH and corticosterone responses were indistinguishable. These results indicate age-related changes in the HNS and HPA axis with an enhanced basal activity opposed to a blunted response to stressors with increasing age. The increased basal release of AVP within the PVN suggests a role of intracerebral AVP in age-associated alterations of HPA axis regulation.

Adrenocorticotropic Hormone↗
PubMed2000

Glucocorticoid receptor impairment enhances impulsive responding in transgenic mice performing on a simultaneous visual discrimination task.

Transgenic mice with impaired glucocorticoid receptor (GR) function were tested for their ability to learn and perform a series of simultaneous visual discriminations which allowed a dissociation between accuracy of discrimination from those of motivation and behavioural disinhibition. Animals were first trained on an operant five-choice simultaneous discrimination autoshaping procedure, followed by a continuous reinforcement schedule on that task. Subsequently, the number of choices was limited to two and data were analysed according to the mathematical methods of signal detection theory (SDT). The effects of GR-antisense expression on accuracy when different rates of responding were required were studied under different fixed ratio response requirements (FR1-FR10). Autoshaping was retarded in transgenic animals and accuracy was impaired in both the five-choice and the two-choice discrimination tasks, although transgenic mice showed clear evidence for learning. Under conditions of low response requirements, transgenic mice showed increased response and cognitive biases, but reduced perceptual bias, and a behavioural disinhibition, characterized by a reduction in errors of omission, decreased response latencies and increased number of responses during the inter-trial interval. Increasing the response requirement improved performance in transgenic animals as reflected by enhanced accuracy. Moreover, transgenics were less susceptible to the deleterious effects of higher response requirements, as indicated by relatively unaffected bias measures in this group, while bias increased in controls. These results indicate that altered performance in GR-antisense transgenic animals cannot simply be interpreted as a mnemonic deficit, but that altered motivation and enhanced impulsive responding may account for some of these impairments.

Animals↗
PubMed2000

Schizophrenia: glutathione deficit in cerebrospinal fluid and prefrontal cortex in vivo.

Schizophrenia is a major psychiatric disease, which affects the centre of the personality, with severe problems of perception, cognition as well as affective and social behaviour. In cerebrospinal fluid of drug-free schizophrenic patients, a significant decrease in the level of total glutathione (GSH) by 27% (P<0.05) was observed as compared to controls, in keeping with the reported reduced level of its metabolite gamma-glutamylglutamine. With a new non-invasive proton magnetic resonance spectroscopy methodology, GSH level in medial prefrontal cortex of schizophrenic patients was found to be 52% (P = 0.0012) lower than in controls. GSH plays a fundamental role in protecting cells from damage by reactive oxygen species generated among others by the metabolism of dopamine. A deficit in GSH would lead to degenerative processes in the surrounding of dopaminergic terminals resulting in loss of connectivity. GSH also potentiates the N-methyl-D-aspartate (NMDA) receptor response to glutamate, an effect presumably reduced by a GSH deficit, leading to a situation similar to the application of phencyclidine (PCP). Thus, a GSH hypothesis might integrate many established biological aspects of schizophrenia.

Adolescent↗
PubMed2000

Acute transcranial magnetic stimulation of frontal brain regions selectively modulates the release of vasopressin, biogenic amines and amino acids in the rat brain.

Using intracerebral microdialysis in urethane-anaesthetized adult male Wistar rats, we monitored the effects of acute repetitive transcranial magnetic stimulation (rTMS; 20 trains of 20 Hz, 2.5 s) on the intrahypothalamic release of arginine vasopressin (AVP) and selected amino acids (glutamate, glutamine, aspartate, serine, arginine, taurine, gamma-aminobutyric acid) and the intrahippocampal release of monoamines (dopamine, noradrenaline, serotonin) and their metabolites (homovanillic acid, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid). The stimulation parameters were adjusted according to the results of accurate computer reconstructions of the current density distributions induced by rTMS in the rat and human brains, ensuring similar stimulation patterns in both cases. There was a continuous reduction in AVP release of up to 50% within the hypothalamic paraventricular nucleus in response to rTMS. In contrast, the release of taurine, aspartate and serine was selectively stimulated within this nucleus by rTMS. Furthermore, in the dorsal hippocampus the extracellular concentration of dopamine was elevated in response to rTMS. Taken together, these data provide the first in vivo evidence that acute rTMS of frontal brain regions has a differentiated modulatory effect on selected neurotransmitter/neuromodulator systems in distinct brain areas.

Amino Acids↗
PubMed2000

Glucocorticoid receptor impairment alters CNS responses to a psychological stressor: an in vivo microdialysis study in transgenic mice.

To study the consequences of impaired functioning of the glucocorticoid receptor (GR) for behavioural, neuroendocrine and neurochemical responses to a psychological stressor, a transgenic mouse expressing antisense RNA against GR was used. Previous studies on these transgenic mice have shown that impairment of GR evolves in disturbed neuroendocrine regulation and certain behavioural responses to stress. Here we investigated putative disturbances on the level of brain neurotransmission in GR-impaired (GR-i) mice using an in vivo microdialysis method. Through a microdialysis probe in the hippocampus, serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and free corticosterone [as an index of hypothalamic-pituitary-adrenocortical (HPA) axis activity] were monitored. Moreover, specific behaviours (e.g. grooming, eating/drinking, sniffing, nest building and locomotion) displayed by the mice during collection of the dialysates were scored. Measurement of dialysate concentrations of corticosterone on days 1 and 3 after insertion of the microdialysis probe showed that the free levels of this glucocorticoid were significantly lower in GR-i mice toward the evening. On day 2 after insertion of the microdialysis probe, baseline values of dialysate corticosterone, 5-HT and 5-HIAA were assessed, after which mice were exposed to a rat placed into their home cage. The rat and mouse were separated by a Plexiglas wall. A positive correlation between baseline hippocampal extracellular levels of 5-HT and 5-HIAA and the time spent performing active behaviours was observed in both genotypes. The main active behaviour performed at the baseline was grooming behaviour. During the rat exposure period, control mice remained mostly sitting and/or lying with their eyes fixed on the rat. Moreover, they showed a profound rise in free corticosterone levels. In contrast, GR-i mice displayed significantly more activities along the separation wall and a trend toward more grooming behaviour, but no increase of free corticosterone. In both mouse lines, exposure to a rat increased hippocampal extracellular levels of 5-HT and 5-HIAA. The rise in 5-HT was, however, more pronounced in the GR-i mice. From these data it may be concluded that life-long GR impairment has profound consequences for behavioural and neuroendocrine responses to a psychological stressor. Moreover, long-term impaired functioning of GR evolves in hyper-responsiveness of the raphe-hippocampal serotonergic system.

Animals↗
PubMed2000

Subtle shifts in the ratio between pro- and antiapoptotic molecules after activation of corticosteroid receptors decide neuronal fate.

Glucocorticoid receptor (GR) activation induces apoptosis of granule cells in the hippocampus. In contrast, neuroprotection is seen after mineralocorticoid receptor (MR) activation. To date there is no in vivo evidence for direct interactions between corticosteroids and any of the key regulatory molecules of programmed cell death. In this report, we show that the opposing actions of MR and GR on neuronal survival result from their ability to differentially influence the expression of members of the bcl-2 gene family; specifically, in the rat hippocampus, activation of GR induces cell death by increasing the ratio of the proapoptotic molecule Bax relative to the antiapoptotic molecules Bcl-2 or Bcl-x(L); the opposite effect is observed after stimulation of MR. The same results were obtained in both young and aged animals; however, older subjects (which were more susceptible to GR-mediated apoptosis) tended to express the antiapoptotic genes more robustly. Using a loss-of-function mouse model, we corroborated the observations made in the rat, demonstrating Bax to be essential in the GR-mediated cell death-signaling cascade. In addition, we show that GR activation increases and MR activation decreases levels of the tumor suppressor protein p53 (a direct transcriptional regulator of bax and bcl-2 genes), thus providing new information on the early genetic events linking corticosteroid receptors with apoptosis in the nervous system.

Aging↗
PubMed2000

Functional cross-talk among cytokines, T-cell receptor, and glucocorticoid receptor transcriptional activity and action.

The main communicators between the neuroendocrine and immune systems are cytokines and hormones. We studied the molecular interaction between immune activators (cytokines and T-cell receptors [TCRs]) and the glucocorticoid receptor (GR) in cells in which glucocorticoids play a key regulatory function: (1) cellular targets of TNF-induced cytotoxicity; (2) the pituitary gland; and (3) thymic cells. Cytokines (TNF-alpha and IL-1) increase glucocorticoid-induced transcriptional activity of the GR via the DNA-glucocorticoid response elements (GREs) in cells transfected with a glucocorticoid-inducible reporter plasmid. As a functional physiological correlate, priming of fibroblastic cells with a low dose of TNF significantly increases the sensitivity to glucocorticoid inhibition of TNF-induced apoptosis (without involving NF-kappa B). Priming of AtT-20 mouse corticotrophs and Cushing pituitary cells with IL-1 increases the sensitivity to glucocorticoid inhibition of CRH-induced ACTH/POMC expression. In thymocytes, activation of the T-cell receptor counteracts the glucocorticoid-induced thymic apoptosis by downregulating the glucocorticoid action on GRE-driven apoptotic genes. Thus, cytokines and immune mediators prevent their own deleterious effects not only by stimulating glucocorticoid production, but also by modifying the sensitivity of the target cells for the glucocorticoid counter-regulatory action. The functional cross-talk at the molecular level between immune signals and glucocorticoids is essential to determine the biological response to both mediators and constitutes the ultimate level of interaction between the immune and neuroendocrine mediators.

Animals↗
PubMed2000

Rifampicin is not an activator of glucocorticoid receptor.

Rifampicin, an antibiotic widely used in tuberculosis therapy, is known to exert psychotropic side effects in some patients. Recently, rifampicin has been reported to activate the glucocorticoid receptor (GR) in human hepatocytes. Because there is evidence that increased levels of glucocorticoids may induce cognitive impairment, sometimes culminating in depression, the side effects of rifampicin may result from GR activation in central nerve cells. Therefore, we used reporter gene assays to determine whether rifampicin displays glucocorticoid-like effects in human neuroblastoma SK-N-MC cells or mouse hippocampal HT22 cells. Rifampicin was unable to elicit any detectable transactivation of GR in both cell types, whereas cortisol or dexamethasone led to a potent transcriptional response. Rifampicin was also inactive in the same HepG2 cell line that was originally used to demonstrate the effect of rifampicin on GR. Moreover, rifampicin was unable to compete with dexamethasone for binding to GR. Finally, by blocking the multidrug resistance P-glycoprotein transporter (a xenobiotic extrusion pump) with verapamil or cyclosporin A, we excluded the possibility that the lack of effect by rifampicin was due to its export from the cell. Our results establish that rifampicin does not activate GR, and rule out the hypothesis that the psychotropic side effects of rifampicin treatment are a consequence of GR activation.

ATP Binding Cassette Transporter, Subfamily B↗