Neurobiological consequences of juvenile stress: A GABAergic perspective on risk and resilience

ALBRECHT, A., MÜLLER, I., ARDI, Z., ÇALIŞKAN, G., GRUBER, D., IVENS, S., SEGAL, M., BEHR, J., HEINEMANN, U., STORK, O., and RICHTER-LEVIN, G. Neurobiological consequences of juvenile stress: A GABAergic perspective on risk and resilience. NEUROSCI BIOBEHAV REV XXX-XXX, 2016.- Childhood adversity is among the most potent risk factors for developing mood and anxiety disorders later in life. Therefore, understanding how stress during childhood shapes and rewires the brain may optimize preventive and therapeutic strategies for these disorders. To this end, animal models of stress exposure in rodents during their post-weaning and pre-pubertal life phase have been developed. Such 'juvenile stress' has a long-lasting impact on mood and anxiety-like behavior and on stress coping in adulthood, accompanied by alterations of the GABAergic system within core regions for the stress processing such as the amygdala, prefrontal cortex and hippocampus. While many regionally diverse molecular and electrophysiological changes are observed, not all of them correlate with juvenile stress-induced behavioral disturbances. It rather seems that certain juvenile stress-induced alterations reflect the system's attempts to maintain homeostasis and thus promote stress resilience. Analysis tools such as individual behavioral profiling may allow the association of behavioral and neurobiological alterations more clearly and the dissection of alterations related to the pathology from those related to resilience.

Diagnosing necrotic meningioma: a distinctive imaging pattern in diffusion MRI and MR spectroscopy

The differential diagnosis of necrotic meningiomas includes brain abscess and malignant neoplasms. We report and discuss hereby the work-up of two patients diagnosed with necrotic meningioma using diffusion-weighted imaging, magnetic resonance spectroscopy, resective surgery, and histopathology. The purpose of the present article is to add to the scant literature on the use of advanced imaging modalities in the routine investigation of brain lesions and their utility in arriving at the final diagnosis.

Shifts in excitatory/inhibitory balance by juvenile stress: A role for neuron-astrocyte interaction in the dentate gyrus

Childhood trauma is a well-described risk factor for the development of stress-related psychopathology such as posttraumatic stress disorder or depression later in life. Childhood adversity can be modeled in rodents by juvenile stress (JS) protocols, resulting in impaired coping with stressful challenges in adulthood. In the current study, we investigated the long-lasting impact of JS on the expression of molecular factors for glutamate and γ-aminobutyric acid (GABA) uptake and turnover in sublayers of the dentate gyrus (DG) using laser microdissection and quantitative real-time polymerase chain reaction. We observed reduced mRNA expression levels after JS for factors mediating astrocytic glutamate and GABA uptake and degradation. These alterations were prominently observed in the dorsal but not ventral DG granule cell layer, indicating a lasting change in astrocytic GABA and glutamate metabolism that may affect dorsal DG network activity. Indeed, we observed increased inhibition and a lack of facilitation in response to paired-pulse stimulation at short interstimulus intervals in the dorsal DG after JS, while no alterations were evident in basal synaptic transmission or forms of long-term plasticity. The shift in paired-pulse response was mimicked by pharmacologically blocking the astrocytic GABA transporter GAT-3 in naïve animals. Accordingly, reduced expression levels of GAT-3 were confirmed at the protein level in the dorsal granule cell layer of rats stressed in juvenility. Together, these data demonstrate a lasting shift in the excitatory/inhibitory balance of dorsal DG network activity by JS that appears to be mediated by decreased GABA uptake into astrocytes.

Psychometric properties of a Russian version of the General Health Questionnaire-28

BACKGROUND

The 28-item General Health Questionnaire (GHQ-28) is a scaled version of the General Health Questionnaire that has been used internationally to screen for mental disorders in nonpsychiatric populations. There is great need to validate international screening instruments in the Russian language for their use in post-Soviet countries.

METHODS

200 persons were surveyed in a deprived area of Almaty, Kazakhstan using the Russian version of the GHQ-28 and socioeconomic measures (income level, employment situation and education). We calculated the median and the mean GHQ-28 scores for different socioeconomic subgroups. The internal reliability was tested using Cronbach's α coefficient and intersubscale correlations. We conducted an exploratory factor analysis using varimax rotation.

RESULTS

The median score of the GHQ-28 was 2 (mean = 3.56; SD = 5.09) for the total sample. Higher age, unemployment and female gender were significantly associated with high mean GHQ-28 scores. Cronbach's α coefficient was 0.92 for the total scale. Exploratory factor analysis revealed four factors explaining 50.07% of the variance. The factor Anxiety/Insomnia accounted for 14.87%, Severe Depression for 13.74%, Social Dysfunction for 13.47% and Somatic Symptoms for 8.81% of the variance.

CONCLUSIONS

The test showed good internal consistency. The median GHQ-28 score was relatively low compared to other countries. The subscale Severe Depression including items on suicidal ideation may have a lower acceptance than the other subscales Somatic Symptoms, Anxiety/Insomnia and Social Dysfunction.

Use of psychiatric inpatient capacities and diagnostic practice in Tashkent/Uzbekistan as compared to Berlin/Germany

OBJECTIVES

The present study shows a comparison of diagnoses used for the treatment of urban psychiatric inpatients in Tashkent/Uzbekistan and Berlin/Germany. Differential diagnostic practices related to different traditions in psychopathology between the two settings are analysed to explain part of the difference in relative frequencies of the diagnoses.

METHODS

We conducted a cross-sectional survey of diagnoses used for the treatment of 845 inpatients including 17 out of 18 wards of the Tashkent psychiatric hospital and of all 2,260 psychiatric and psychotherapeutic inpatients in Berlin in October 2008. Relative frequencies of diagnostic categories were calculated for each setting and compared between the two settings using the Chi-square test. A descriptive analysis of differential diagnostic practice is used to explain differences in relative frequencies.

RESULTS

Patients diagnosed with schizophrenia (59.3 vs. 21.0%), with organic mental disorders (20.5 vs. 8.3%), with mental retardation (6.9 vs. 0.2%) and with neurasthenia (1.4 vs. 0.0%) had larger relative frequencies of the psychiatric inpatient population in Tashkent than in Berlin. Patients diagnosed with unipolar depression (24.1 vs. 0.9%), substance use disorder (17.4 vs. 6.4%), adjustment disorder (6.0 vs. 0.4%), schizoaffective disorder (4.9 vs. 0.0%), mania and bipolar disorder (5.3 vs. 0.4%), personality disorder (3.2 vs. 2.0%) and anxiety disorder (3.1 vs. 0.1%) had larger relative frequencies in Berlin than in Tashkent. The diagnostic concept of schizophrenia in Tashkent includes patients with affective psychoses, schizoaffective psychoses and delusional disorders. In Tashkent, mental disorders are more readily associated with organic brain disease such as head trauma or vascular disease than in Berlin.

CONCLUSIONS

In Tashkent, most of the psychiatric inpatient capacities are used for the treatment of schizophrenia and organic mental disorders, whereas in Berlin patients with affective disorders, schizophrenia and substance use disorders are most commonly treated as inpatients. The differences can in part be explained by differential diagnostic traditions between the Russian/post-Soviet nosology and the use of the ICD.

Blood-brain barrier breakdown as a novel mechanism underlying cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) may occur as a severe complication following surgical treatment of carotid stenosis. However, the mechanism inducing neurological symptoms in CHS remains unknown. We describe a patient with CHS presenting with seizures 24 h following carotid endarterectomy. Imaging demonstrated early ipsilateral blood-brain barrier (BBB) breakdown with electroencephalographic evidence of cortical dysfunction preceding brain edema. Using in vitro experiments on rat cortical tissue, we show that direct exposure of isolated brain slices to a serum-like medium induces spontaneous epileptiform activity, and that neuronal dysfunction is triggered by albumin. We propose BBB breakdown and subsequent albumin extravasation as a novel pathogenic mechanism underlying CHS and a potential target for therapy.

Blood-brain barrier disruption results in delayed functional and structural alterations in the rat neocortex

Disruption of the blood-brain barrier (BBB) is a characteristic finding in common neurological disorders. Human data suggest BBB disruption may underlie cerebral dysfunction. Animal experiments show the development of epileptiform activity following BBB breakdown. In the present study we investigated the neurophysiological, structural and functional consequences of BBB disruption. Adult rats underwent focal BBB disruption in the rat sensory-motor cortex using the bile salt sodium deoxycholate (DOC). Magnetic resonance imaging in-vivo showed an early BBB disruption with delayed reduction in cortical volume. This was associated with a reduced number of neurons and an increased number of astrocytes. In-vitro experiments showed that the threshold for spreading depression and the propagation velocity of the evoked epileptic potentials were increased 1 month after treatment. Furthermore, animals' motor functions deteriorated during the first few weeks following BBB disruption. Treatment with serum albumin resulted in a similar cell loss confirming that the effect of DOC was due to opening of the BBB. Our findings suggest that delayed neurodegeneration and functional impairment occur following the development of the epileptic focus in the BBB-permeable cerebral cortex.

TGF-beta receptor-mediated albumin uptake into astrocytes is involved in neocortical epileptogenesis

It has long been recognized that insults to the cerebral cortex, such as trauma, ischaemia or infections, may result in the development of epilepsy, one of the most common neurological disorders. Human and animal studies have suggested that perturbations in neurovascular integrity and breakdown of the blood-brain barrier (BBB) lead to neuronal hypersynchronization and epileptiform activity, but the mechanisms underlying these processes are not known. In this study, we reveal a novel mechanism for epileptogenesis in the injured brain. We used focal neocortical, long-lasting BBB disruption or direct exposure to serum albumin in rats (51 and 13 animals, respectively, and 26 controls) as well as albumin exposure in brain slices in vitro. Most treated slices (72%, n = 189) displayed hypersynchronous propagating epileptiform field potentials when examined 5-49 days after treatment, but only 14% (n = 71) of control slices showed similar responses. We demonstrate that direct brain exposure to serum albumin is associated with albumin uptake into astrocytes, which is mediated by transforming growth factor beta receptors (TGF-betaRs). This uptake is followed by down regulation of inward-rectifying potassium (Kir 4.1) channels in astrocytes, resulting in reduced buffering of extracellular potassium. This, in turn, leads to activity-dependent increased accumulation of extracellular potassium, resulting in facilitated N-methyl-d-aspartate-receptor-mediated neuronal hyperexcitability and eventually epileptiform activity. Blocking TGF-betaR in vivo reduces the likelihood of epileptogenesis in albumin-exposed brains to 29.3% (n = 41 slices, P < 0.05). We propose that the above-described cascade of events following common brain insults leads to brain dysfunction and eventually epilepsy and suggest TGF-betaRs as a possible therapeutic target.

Lasting blood-brain barrier disruption induces epileptic focus in the rat somatosensory cortex

Perturbations in the integrity of the blood-brain barrier have been reported in both humans and animals under numerous pathological conditions. Although the blood-brain barrier prevents the penetration of many blood constituents into the brain extracellular space, the effect of such perturbations on the brain function and their roles in the pathogenesis of cortical diseases are unknown. In this study we established a model for focal disruption of the blood-brain barrier in the rat cortex by direct application of bile salts. Exposure of the cerebral cortex in vivo to bile salts resulted in long-lasting extravasation of serum albumin to the brain extracellular space and was associated with a prominent activation of astrocytes with no inflammatory response or marked cell loss. Using electrophysiological recordings in brain slices we found that a focus of epileptiform discharges developed within 4-7 d after treatment and could be recorded up to 49 d postoperatively in >60% of slices from treated animals but only rarely (10%) in sham-operated controls. Epileptiform activity involved both glutamatergic and GABAergic neurotransmission. Epileptiform activity was also induced by direct cortical application of native serum, denatured serum, or albumin-containing solution. In contrast, perfusion with serum-adapted electrolyte solution did not induce abnormal activity, thereby suggesting that the exposure of the serum-devoid brain environment to serum proteins underlies epileptogenesis in the blood-brain barrier-disrupted cortex. Although many neuropathologies entail a compromised blood-brain barrier, this is the first direct evidence that it may have a role in the pathogenesis of focal cortical epilepsy, a common neurological disease.