Extra-hepatic replication and infection of hepatitis E virus in neuronal-derived cells.

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and a member of the genus Orthohepevirus in the family Hepeviridae. Infection usually leads to acute hepatitis that can become fulminant, particularly among pregnant women and in patients with preexisting liver disease, or may evolve to a chronic state, especially in immunosuppressed individuals. HEV has been shown to produce a range of extra-hepatic manifestations including aplastic anaemia, acute thyroiditis, glomerulonephritis as well as neurological disorders such as Guillain-Barré syndrome, neuralgic amyotrophy and encephalitis. The pathogenesis of these neurological injuries remains largely unknown, and it is also uncertain whether or not HEV can directly infect neuronal cells. In this study, we investigated whether HEV is capable of completing the viral life cycle in human neuronal-derived cell lines such as neuroepithelioma (SK-N-MC), desmoplastic cerebellar medulloblastoma (DAOY), glioblastoma multiforme (DBTRG), glioblastoma astrocytoma (U-373 MG) and oligodendrocytic (M03.13) cells. Following transfection of these cells with HEV Gaussia luciferase reporter virus, all tested cell lines supported HEV RNA replication. Furthermore, extra- and intracellular viral capsid was detected by an HEV antigen ELISA as a marker for virus assembly and release. Permissiveness for HEV cell entry could be demonstrated for the oligodendrocytic cell line M03.13. In conclusion, these results indicate that HEV tropism is not restricted to the liver and HEV can potentially complete the full viral life cycle in neuronal-derived tissues explaining neurologic disorders during HEV infection.

Urocortin 1 administered into the hypothalamic supraoptic nucleus inhibits food intake in freely fed and food-deprived rats.

Peptides of the corticotropin-releasing hormone/Urocortin (CRH/Ucn) family are known to suppress appetite primarily via CRH(2) receptors. In the rat hypothalamic supraoptic nucleus (SON), synthesis of both Ucn1 and CRH(2) receptors has been reported, yet little is known about the effects of Ucn1 in the SON on feeding behaviour. We first established the dose-related effects of Ucn1 injected into the SON on the feeding response in both freely fed and 24-h food-deprived rats. A conditioned taste avoidance paradigm was performed to investigate possible generalised effects of local Ucn1 treatment. Administration of Ucn1 into the SON at doses equal to or higher than 0.5 µg significantly decreased food intake in both freely fed and food-deprived rats. The Ucn1-mediated suppression of food intake was delayed in freely fed as compared to food-deprived animals. Conditioning for taste aversion to saccharine appeared at 0.5 and 1 µg of Ucn1. Both the early and the delayed onset of anorexia observed after intra-SON injection of Ucn1 under fasting and fed conditions, respectively, suggest the possible involvement of different CRH receptor subtypes in the two conditions, while the conditioned taste aversion seems to be responsible for the initial latency to eat the first meal in these animals.

Generalization of fear in post-traumatic stress disorder.

Overgeneralization (i.e., the transfer of fear to stimuli not related to an aversive event) is part of alterations in associative fear learning in mental disorders. In the present experimental study, we investigated whether this holds true for post-traumatic stress disorder (PTSD) related to childhood abuse. We expected that fear generalization under experimental conditions reflects generalization of aversive stimuli to different social domains in real life. Sixty-four women with PTSD after childhood abuse and 30 healthy participants (HC) underwent a differential fear conditioning and generalization paradigm. Online risk ratings, reaction time, and fear-potentiated startle served as dependent variables. Based on the subjectively assessed generalization of triggered intrusions across different domains of life, PTSD participants were split into two groups reporting low (low-GEN) and high (high-GEN) generalization. PTSD patients reported a higher expectation of an aversive event. During fear conditioning, they assessed the risk of danger related to a safety cue slower and showed a blunted fear-potentiated startle toward the danger cue. During generalization testing, reaction time increased in the high-GEN patients and decreased in the HC group with increasing similarity of a stimulus with the conditioned safety cue. Alterations of fear learning in PTSD suggest impaired defensive responses in case of a high threat probability. Moreover, our findings bridge the gap between the generalization of aversive cues during everyday life and laboratory-based experimental parameters: impairments in the processing of cues signaling safety generalize particularly in those patients who report a spreading of PTSD symptoms across different domains of everyday life.

Role of neuronal nitric oxide synthase in the regulation of the neuroendocrine stress response in rodents: insights from mutant mice.

Nitric oxide (NO) is a free radical gas synthesised from arginine and oxygen by enzymes of the family of the nitric oxide synthase. In particular, the neuronal nitric oxide synthase (nNOS) is highly expressed by cells of the hypothalamic paraventricular nucleus, where the sympatho-adrenal system, the hypothalamic-pituitary-adrenal axis and the hypothalamic-neurohypophyseal system originate. These structures are deputed to regulate the neuroendocrine stress response. In the past years, evidence has been accumulated to suggest that NO of nNOS origin plays a significant role in modulating the activity of the above mentioned systems under acute stressor exposure. The availability of nNOS knock-out mice allowed to investigate not only the physiological consequences of a constitutive lack of NO of nNOS origin at the hormonal and molecular level, but also to examine possible behavioural alterations. In this review, we shall discuss and confront the current trends of research in this area, especially focusing on the latest findings gained from genetically modified mice.

Reduced urocortin 1 immunoreactivity in the non-preganglionic Edinger-Westphal nucleus during late pregnancy in rats.

Pregnancy is accompanied by an array of adaptive changes that play an important role in pre- and postnatal events. In rats, urocortin 1, a corticotropin-releasing factor-like peptide, is expressed mainly in the non-preganglionic Edinger-Westphal nucleus. We investigated the number of neurons immunoreactive for urocortin 1 at three different levels of the Edinger-Westphal nucleus in female rats by immunohistochemistry. The number of urocortin 1 immunoreactive cells was found to be decreased in pregnant rats compared to virgin rats. These results indicate that the hormonal status of the female rat affects urocortin 1 immunoreactive neurons in the non-preganglionic Edinger-Westphal nucleus and its signaling to target brain areas.

Behavioral consequences of intracerebral vasopressin and oxytocin: focus on learning and memory.

Since the pioneering work of David de Wied and his colleagues, the neuropeptides arginine vasopressin and oxytocin have been thought to play a pivotal role in behavioral regulation in general, and in learning and memory in particular. The present review focuses on the behavioral effects of intracerebral arginine vasopressin and oxytocin, with particular emphasis on the role of these neuropeptides as signals in interneuronal communication. We also discuss several methodological approaches that have been used to reveal the importance of these intracerebral neuropeptides as signals within signaling cascades. The literature suggests that arginine vasopressin improves, and oxytocin impairs, learning and memory. However, a critical analysis of the subject indicates the necessity for a revision of this generalized concept. We suggest that, depending on the behavioral test and the brain area under study, these endogenous neuropeptides are differentially involved in behavioral regulation; thus, generalizations derived from a single behavioral task should be avoided. In particular, recent studies on rodents indicate that socially relevant behaviors triggered by olfactory stimuli and paradigms in which the animals have to cope with an intense stressor (e.g., foot-shock motivated active or passive avoidance) are controlled by both arginine vasopressin and oxytocin released intracerebrally.

Placental glucose transporter expression is regulated by glucocorticoids.

Although glucocorticoids play important roles in development and fetal programming, they are widely used for treatment of a variety of diseases during pregnancy. In various tissues, glucocorticoids down-regulate glucose transport systems; however, their effects on glucose transporters in the placenta are unknown. In the present study, the glucose carrier proteins GLUT1 and GLUT3 were localized in the trophoblast and endothelium of the human, rat, and mouse placenta. Subsequently, it was investigated whether glucocorticoids affect messenger ribonucleic acid and protein expression of these molecules by Northern and Western blotting using 1) human term placental trophoblast cells cultured in the presence or absence of 0.5, 5, and 50 micromol/L triamcinolone; 2) placentas of rats that received a single i.p. dose of 0.38 mg/kg triamcinolone; and 3) placentas of transgenic mice bearing an antisense glucocorticoid receptor gene construct. In all of these systems, both glucose transporters were significantly down-regulated (P < 0.05), with the exception of increased GLUT3 messenger ribonucleic acid and protein levels in transgenic mice. The results demonstrate that triamcinolone is a potent regulator of placental GLUT1 and GLUT3 expression involving the glucocorticoid receptor. We speculate that impaired expression of placental glucose transporters after glucocorticoid administration might contribute to the adverse side-effects, the foremost of which is a growth-retarded fetus, of this treatment during pregnancy.

Neuroendocrine and behavioral effects of repetitive transcranial magnetic stimulation in a psychopathological animal model are suggestive of antidepressant-like effects.

The neuroendocrine and behavioral effects of repetitive transcranial magnetic stimulation (rTMS) were investigated in two rat lines selectively bred for high and low anxiety-related behavior. The stimulation parameters were adjusted according to the results of accurate computer-assisted and magnetic resonance imaging-based reconstructions of the current density distributions induced by rTMS in the rat and human brain, ensuring comparable stimulation patterns in both cases. Adult male rats were treated in two 3-day series under halothane anesthesia. In the forced swim test, rTMS-treatment induced a more active coping strategy in the high anxiety-related behavior rats only (time spent struggling; 332% vs. controls), allowing these animals to reach the performance of low anxiety-related behavior rats. In contrast, rTMS-treated low anxiety-related behavior rats did not change their swimming behavior. The development of active coping strategies in high anxiety-related behavior rats was accompanied by a significantly attenuated stress-induced elevation of plasma corticotropin and corticosterone concentrations. In summary, the behavioral and neuroendocrine effects of rTMS of frontal brain regions in high anxiety-related behavior rats are comparable to the effects of antidepressant drug treatment. Interestingly, in the psychopathological animal model repetitive transcranial magnetic stimulation induced changes in stress coping abilities in the high-anxiety line only.

Neointimal growth can be influenced by local adventitial gene manipulation via a needle injection catheter.

Revascularization by percutaneous transluminal coronary angioplasty is limited in the long-term by restenosis, which is luminal renarrowing in the first 6 months after the procedure. Smooth muscle cell proliferation is thought to be an important factor in restenosis; this leads to neointima formation and arterial lumen narrowing. Local therapy delivered perivascularly may have an effect on events in the neointima and reduce restenosis. The effect of delivering expression vector plasmids for senescent cell-derived inhibitor SDI-1, which regulates cell proliferation, and its antisense, into the perivascular tissue of injured arteries was investigated in a porcine arterial injury model using a needle injection catheter. Transfection efficiency, biological effect and plasmid dissemination were evaluated in arterial and organ tissue sections between 2 days and 4 months. A limited number of adventitial, medial and neointimal cells were transfected up to 4 months. sdi gene transfer did not result in a change in neointima. Transfer of antisense sdi resulted in an increase in neointima after 3 weeks. No DNA plasmid was detected in control tissues. Liposomally-mediated adventitial local gene delivery is feasible and safe using the needle injection catheter in a porcine model. A limited number of cells was transfected, with expression of transfected genes up to 4 months after delivery. A transient biological effect with increased neointima was observed after delivery of the antisense sdi gene.

Dissociated central and peripheral release of vasopressin, but not oxytocin, in response to repeated swim stress: new insights into the secretory capacities of peptidergic neurons.

To investigate the effects of an ethologically-relevant stressor on central and peripheral release of arginine vasopressin and oxytocin, we forced adult male Wistar rats to swim for 10 min and simultaneously measured the release of the two peptides (i) within the hypothalamic supraoptic and paraventricular nuclei (by means of the microdialysis technique) and (ii) into the blood (by chronically-implanted jugular venous catheters). Forced swimming caused a significant rise in the release of arginine vasopressin and oxytocin within both the supraoptic nuclei (four-fold and three-fold, respectively) and the paraventricular nuclei (three-fold and four- to five-fold, respectively). Release patterns measured before, during and after repeated stress exposure on three consecutive days indicated that, at the level of the hypothalamus, the two neuropeptides are critically involved in the rats' stress response in a peptide-, locus- and stress-specific manner. Particularly, despite a general reduction of the recovery of the microdialysis probes over the time, the release of arginine vasopressin within the paraventricular nuclei and of oxytocin within the supraoptic nuclei tended to increase upon repeated stress exposure. Measurement of plasma peptide concentrations revealed that the central release of oxytocin was accompanied by a secretion of this peptide into the systemic circulation. In contrast, arginine vasopressin, assayed in the same plasma samples, failed to respond to the stressor. The latter finding is consistent with a dissociated release of the neuropeptide from different parts of a single neuron (soma/dendrites vs axon terminals). It provides evidence that under physiological conditions plasma hormone levels do not necessarily reflect the secretory activity of central components of the respective neuropeptidergic system.

Accuracy of spiral computed tomography for identifying arterial and venous coronary graft patency.

Late outcome after coronary artery bypass grafting (CABG) mainly depends on the status of graft patency. The recent generation of spiral computed tomography (SCT) scanners may have potential in the long-term follow-up of CABG. In this study, graft patency in patients with internal mammary (IMA) and venous CABG was investigated using SCT and angiography. Forty-nine consecutive patients (age 61 +/- 8 years, 45 men) who had undergone CABG were examined by SCT and angiography 22 +/- 6 months after CABG. In total, 134 bypass grafts (42 IMA and 92 venous grafts) were analyzed. The angiographically determined patency rate of grafts was 86% for IMA (n = 36 of 42) and 74% for venous grafts (n = 68 of 92). By SCT, 32 IMA and 64 venous grafts were diagnosed correctly as patent. Sensitivity was 89% (IMA) and 94% (venous); overall sensitivity was 92%. None of the truly occluded venous grafts was diagnosed falsely patent by SCT (specificity 100%), whereas the specificity of IMA graft visualization was somewhat lower (88%, p = NS [overall 97%]). The accuracy for a patent graft was 88% (IMA) and 96% (venous CABG, p = NS). Compared with previous studies, these data suggest that SCT using one of the recent generation scanners (single scan time 0.75 second) is a highly accurate and relatively noninvasive approach for assessing not only saphenous vein graft patency, but also IMA graft patency. To date, this technique has only limited use in visualizing graft stenosis or distal anastomosis site patency.

Endocrine and behavioral effects of airpuff-startle in rats.

Adult male rats chronically implanted with cannulae in the jugular vein were used to characterize the endocrine and behavioral consequences of airpuff-startle. In the first series of experiments, resting animals subjected to three blocks of airpuff (blocks of three airpuffs each with each block separated by 1 min) showed a 10-fold increase in plasma adrenocorticotropin (ACTH) and corticosterone levels, indicating a significant but moderate activation of the hypothalamo-pituitary-adrenal (HPA) axis when compared with the untreated controls (n = 5 each). In the second series of experiments, monitoring of anxiety-related behavior in the defensive withdrawal paradigm revealed a significant increase in anxiety induced by airpuff-startle application compared with the untreated controls (n = 10 each). This behavioral effect, however, was not correlated with plasma hormone levels, as blood samples taken immediately before and 12 min after exposure to airpuff-startle and exposure to the defensive withdrawal paradigm showed a significant rise in ACTH and corticosterone in both groups. In summary, the findings of the present study indicate the airpuff-startle (1) is a potent stimulus in the activation of the HPA axis, and (2) increases anxiety-related behavior as measured in the defensive withdrawal paradigm. Furthermore, the results of our study support the hypothesis that peripheral endocrine parameters that are used to measure activation of the HPA axis do not necessarily correlate with behavioral data obtained in tests with are thought to measure anxiety.

Release of vasopressin within the brain contributes to neuroendocrine and behavioral regulation.

In addition to its peripheral secretion from the neurohypophysis, the neuropeptide vasopressin (VP) is released within the mammalian brain from probably all parts of the neuronal membrane. In particular the development of brain microdialysis in vivo together with blood microdialysis or blood sampling provides the advantage of being able to reliably compare the dynamic release patterns into different compartments of the organism. The central VP release within hypothalamic (e.g., supraoptic, paraventricular and suprachiasmatic nuclei) and limbic (e.g., septum, amygdala) rat brain areas is stimulated by a variety of substances and stressors, including interleukin-1 beta, social defeat and forced swimming. Furthermore, it is characterized by positive and negative feedback mechanisms and the capacity of the VP system for co-ordinated or independent release, the latter being observed, for example, during social defeat. This emotional stressor, in contrast to exposure to a novel cage, increased VP release within the supraoptic nucleus, but not into plasma. This failure to release VP peripherally could be observed also during forced swimming, despite a dramatic rise in plasma osmolality and a markedly stimulated central release. In another series of experiments we studied the effects of centrally-released VP on cognitive and emotional aspects of behavior using reverse microdialysis for antagonist administration during the behavioral tests and antisense targeting to downregulate either VP or its local V1 receptor subtype. In this way, centrally (in particular septally) released VP could be shown to be causally involved in short-term memory and anxiety-related behavior. Furthermore, VP release within the hypothalamic paraventricular nucleus is likely to provide a negative tonus on the activity of the hypothalamic-pituitary-adrenocortical axis. This neuroendocrine effect together with cognitive, emotional and immunological effects of centrally released VP is thought to be essential to ensure adequate behavior of the animal during challenging situations and to contribute to the development of efficient coping strategies.

Simultaneous monitoring of intracerebral release and behavior: endogenous vasopressin improves social recognition.

We previously reported that direct osmotic stimulation of the supraoptic nucleus (SON) of rats via a microdialysis probe produces a robust 'rebound' release of endogenous vasopressin (AVP) into the extracellular fluid of this hypothalamic nucleus. We now demonstrate in a combined microdialysis and push-pull perfusion study that this intranuclear release is accompanied by increased AVP release in the septum. Simultaneous monitoring of intranuclear release and behavioral performance in the same animal indicated a significant correlation between the amount of endogenously released AVP and improved social memory based on the olfactory discriminative capacities of adult male rats. This memory improvement was partially blocked by local administration of a AVP V1 receptor antagonist either into the SON or septum. These findings indicate that direct osmotic stimulation of the supraoptic nucleus, which increases intracerebral vasopressin release, improves the acquisition and/or processing of olfactory stimuli. Thus, the endogenous neuropeptide fulfills one of the major criteria for being causally involved as a neurotransmitter/neuromodulator in behavioral performance.

Emotional stress triggers intrahypothalamic but not peripheral release of oxytocin in male rats.

Previous experiments have shown that an exposure to defined stressors activates not only the 'classical' endocrine stress response but also the intrahypothalamic and peripheral release of oxytocin. In the present study we investigated the effects of an acute social defeat experience on the release of oxytocin within the hypothalamic supraoptic nucleus, just outside of the supraoptic nucleus toward the midline within the anterior ventro-lateral part of the hypothalamus, and into plasma of adult male rats. Our results demonstrate that emotional stress triggers the release of oxytocin into the extracellular fluid of both the supraoptic nucleus and the anterior ventro-lateral part of the hypothalamus (up to approximately 320% and 170%, respectively). Interestingly, oxytocin release within the latter brain area, which is likely to originate from axons forming the hypothalamo-neurohypophysial tract, was higher in absolute terms than that within the supraoptic nucleus itself, both under basal conditions and in response to social defeat. In contrast to intrahypothalamic release patterns, plasma oxytocin levels remained virtually unchanged upon stressor exposure. This demonstrates that the release of oxytocin within the hypothalamus is triggered by emotional stress. Furthermore, it indicates that under physiological conditions the release of oxytocin from the dendrites and somata upon axon terminals in the neurohypophysis is differentially regulated. Although not yet studied in detail, it may be hypothesized that the spatial and temporal release pattern of oxytocin is controlled by integrative neuronal networks at different brain levels (including hypothalamus and posterior pituitary) to ensure the appropriate involvement of this peptide in the stress response of the animal.

Vasopressin antisense oligonucleotide induces temporary diabetes insipidus in rats.

The purpose of this study was to downregulate the transcriptional message of arginine vasopressin (AVP) by antisense treatment. A complete phosphorothioate antisense oligodesoxynucleotide corresponding to the beginning of the coding region of rat AVP mRNA was constructed and injected into the lateral ventricle of rats. Within 3-6 h animals exhibited a temporary diabetes insipidus, which lasted up to 9 h. Accordingly, vasopressin immunoreactivity in the hypothalamic nuclei was reduced. Our results demonstrate that a specific and reversible inhibition of neuropeptide expression can be accomplished in the intact hypothalamo-neurohypophysial system by antisense treatment, thus providing a novel tool for studies on stimulus-secretion coupling in vivo.

Long-term antidepressant treatment reduces behavioural deficits in transgenic mice with impaired glucocorticoid receptor function.

Impaired cognitive function and enhanced activity of the hypothalamic-pituitary-adrenocortical system are among the cardinal symptoms of major depression in humans that resolve after successful antidepressant treatment. We used a transgenic mouse model expressing antisense RNA complementary to that of glucocorticoid receptor (GR) mRNA to test the hypothesis that reduced GR function can cause these clinical disturbances. The transgenic mice show profound behavioural changes in a number of animal tests that are indicative of cognitive impairment. These mice also have elevated plasma corticotropin concentrations in response to stress. After long-term treatment with moclobemide, a reversible inhibitor of monoamine oxidase type A that acts clinically as an antidepressant, both the behavioural deficits and the hormonal alterations disappeared. These observations suggest that a transgenic mouse with GR dysfunction may be a useful model for investigation of drug effects on the cognitive and neuroendocrine aspects of depression.

The effects of infusion of arginine vasopressin, oxytocin, or their antagonists into the olfactory bulb upon social recognition responses in male rats.

In the present report, the peptides arginine vasopressin (AVP), oxytocin (OXT) or their respective antagonists were infused bilaterally into the olfactory bulb to assess their effects upon recognition responses. Recognition responses were determined in a social discrimination paradigm and consisted of measuring the amount of investigation directed to either the same (previously exposed) or novel juvenile rats under conditions in which clear recognition responses are either present as tested with a 30 min inter-exposure interval or absent as tested with a 120 min inter-exposure interval. Infusion of AVP or OXT resulted in preserved recognition responses, as tested with a 120 min inter-exposure interval, compared with that observed in vehicle-infused controls. When animals were infused with the AVP or OXT antagonists using two different doses and tested for the display of recognition as tested with the 30 min inter-exposure interval, no effects of these antagonists were obtained with either dose. These results demonstrate that the olfactory bulb represents an additional important central nervous system target site where these peptides can act to preserve social recognition responses. Moreover, our results suggest that the underlying mechanisms by which peptides function within the olfactory bulb differ as a function of whether they are involved with the display versus preservation of recognition responses.

Differential behavioural effects of chronic infusion of CRH 1 and CRH 2 receptor antisense oligonucleotides into the rat brain.

The purpose of this study was to investigate the functional role the two corticotropin-releasing hormone (CRH) receptor subtypes play in regulating the behavioural performance of rats in various well-defined test situations. Antisense oligodeoxynucleotides (ODNs) corresponding to either the rat CRH1 or CRH2 receptor mRNA were infused chronically into the lateral ventricle of male rats via osmotic minipumps (5 microg/0.5 microl/h over 6 days). Control groups received infusions of either a scrambled sequence ODN or mixed bases ODN or vehicle. On day 4 after surgery, the rats were subjected to 10 min of social defeat and immediately afterwards tested on the elevated plus-maze. Compared to a scrambled sequence control ODN, CRH1 receptor antisense ODN infusion was found to exert an anxiolytic-like effect whereas CRH2 receptor antisense ODN infusion had no effect on defeat-induced anxiety-related behaviour. In contrast, the CRH2 receptor antisense ODN increased immobility in a forced swim test whereas CRH1 receptor ODN-treated rats did not differ from controls. No influence of either ODN was found on general locomotor activity in an open field or on short-term memory performance in a social discrimination test. Furthermore, the CRH2 receptor antisense ODN did not affect spatial learning in a Morris water maze task. An additional experiment comparing a mixture of both missense ODNs and a vehicle control group confirmed that the former failed to induce non-specific (toxic) side effects, further substantiating the specificity of the respective antisense effects measured in this study. The results support the hypothesis that the two CRH receptor subtypes selectively mediate differential effects of endogenous CRH or CRH-related peptides at the brain level with the CRHI receptor contributing predominantly to emotional behaviour and the CRH2 receptor being involved in the regulation of stress coping behaviour.

Repetitive transcranial magnetic stimulation induces active coping strategies and attenuates the neuroendocrine stress response in rats.

The effects of repetitive transcranial magnetic stimulation (rTMS) on various brain functions were investigated in adult male Wistar rats. The stimulation parameters were adjusted according to the results of accurate computer-assisted, magnetic resonance imaging-based reconstructions of the current density distributions induced by rTMS in the rat and human brain, ensuring comparable stimulation patterns in both cases. The animals were subjected to daily rTMS-treatment (three trains of 20 Hz; 2.5 s) for 8 weeks from the age of 4 weeks on. In the forced swim test these rats showed a more active stress coping strategy than the control rats. This was accompanied by a significantly attenuated stress-induced elevation of plasma ACTH concentrations. Pituitary changes accounting for the attenuation were ruled out by the corticotropin-releasing hormone test. Baseline concentrations of ACTH and corticosterone were indistinguishable in the two groups. No changes were found in the anxiety-related behavior of the rats on the elevated plus-maze or in behavior during the social interaction test. Accordingly, the binding characteristics of the benzodiazepine agonist [(3)H]flunitrazepam at the benzodiazepine/gamma-aminobutyric acid type A receptor complex were similar in the rTMS and control groups. In summary, chronic rTMS treatment of frontal brain regions in rats resulted in a change in coping strategy that was accompanied by an attenuated neuroendocrine response to stress, thus revealing parallels to the effects of antidepressant drug treatment.