Objective of the study – determination of quantitative characteristics of small extracellular vesicles (sEV) in the blood of patients with non-suicidal self-injury (NSSI) and comparison of the concentration and size of sEV’s in patients with major depressive disorder (MDD) with and without NSSI, as well as an assessment of the relationship between the sizes and concentrations of sEV in the sample with such parameters as the severity of situational and personal anxiety, depression and suicidal risk. The study included 28 patients (11 m./17 f.) with a current episode of major depression and at least five episodes of NSSI in the last 12 months (main group, mean age 28.3 years) and 28 patients with major depression identical in sex and age without NSSI throughout life (comparison group). Patient mental status was assessed using the MINI interview, the Beck Depression Inventory II (BDI II), and the Spielberger Anxiety Scale. Isolation of sEV from blood was carried out using polyethylene glycol (PEG) precipitation and gel filtration. The size and concentration of isolated particles were estimated using dynamic light scattering (DLS) and nanoparticle tracking analysis (ATN). The groups differed significantly in the severity of depression according to the BDI-II questionnaire, the Spielberger Situational Anxiety Scale, and the Spielberger Personality Anxiety Scale. The assessment of suicidal risk, carried out according to the corresponding module of the MINI questionnaire, revealed a significantly larger number of participants with medium and high suicidal risk in the group of patients with NSSI. The sEV fraction was isolated from the blood of the patients of the main group and the comparison group. There were no differences in the concentration and size of sEV between groups of patients with depression with and without NSSI. In our study, the dependence of the concentration and size of sEV on the severity of depression, situational and personal anxiety, and the severity of suicidal risk wasn’t revealed.
Conclusion: NSSI in individuals with major depressive disorder is associated with a more severe course of the disorder (greater severity of depression, situational and personal anxiety), as well as a higher risk of suicide. Our study did not reveal any differences in the quantitative characteristics of sEV in patients with a depressive episode with and without NSSI. Future studies should focus on investigating the structural differences and functional features of sEV in NSSI.
The review analyzes modern concepts about the control of various mechanisms of the hippocampal neuroplasticity in adult mammals and humans by glucocorticoids. Glucocorticoid hormones ensure the coordinated functioning of key components and mechanisms of hippocampal plasticity: neurogenesis, glutamatergic neurotransmission, microglia and astrocytes, systems of neurotrophic factors, neuroinflammation, proteases, metabolic hormones, neurosteroids. Regulatory mechanisms are diverse; along with the direct action of glucocorticoids through their receptors, there are conciliated glucocorticoid-dependent effects, as well as numerous interactions between various systems and components. Despite the fact that many connections in this complex regulatory scheme have not yet been established, the study of the factors and mechanisms considered in the work forms growth points in the field of glucocorticoid-regulated processes in the brain and primarily in the hippocampus. These studies are fundamentally important for the translation into the clinic and the potential treatment/prevention of common diseases of the emotional and cognitive spheres and respective comorbid conditions.
Our study describes the effects of sensory tetanization on neurophysiological and behavioral measures in humans linking cellular studies of long-term potentiation with high-level brain processes. Rapid (every 75ms) presentation of pure tone (1020 Hz, 50ms) for 2 minutes was preceded and followed by oddball blocks that contained the same stimulus presented as deviant (probability of 5–10%) interspersed with standard (80–90%) and deviant tones (5–10%) of adjacent frequencies (1000 and 980Hz, respectively). Mismatch negativity (MMN) component in response to tetanized tone (1020Hz), while being similar to MMN for non-tetanized tone before tetanization, became larger than that after tetanization, pointing to the increase in cortical differentiation of these tones. However, this differentiation was partially due to the MMN decrease after tetanization for tones adjacent to tetanized frequency, suggesting the influence of lateral inhibition to this effect. Although MMN correlated with tone discriminability in a psychophysical task, the behavioral improvement after tetanization was not statistically detectable. To conclude, short-term auditory tetanization affects cortical representation of tones that are not limited to the tetanized stimuli.
Major depressive disorder (MDD) is characterized by dramatic and persistent worsening of mood, as well as a subjective feeling of time slowing. However, experimental data on time perception are inconsistent. As serotonergic dysfunction implicated in MDD etiology, we aim to examine time perception in MDD through the framework of lossy temporal integration model, previously also related to serotonergic transmission. Thirty-one patients with recurrent depressive disorder in partial remission and thirty control participants, without a history of psychiatric and neurological disorders, performed duration discrimination of visual stimuli (duration ranges from 3.2 to 6.4 s) and subjective minute production tasks. To infer about central serotonergic transmission, an electroencephalogram in response to the 1000 Hz tone of different intensity (50, 60, 70 and 80 dB SPL) was recorded. Patients with MDD shorten the past durations in the duration discrimination task significantly less than controls, thus being more objective. No difference in the subjective minute production was recorded. Patients with MDD have also exhibited larger auditory evoked potentials in response to the tones of high intensity (70 and 80 dB SPL) when compared with the controls. This resulted in a steeper slope of auditory evoked potentials by intensity function. These converging findings suggest a lower loss rate of neuronal temporal accumulator modulated by serotonergic transmission in patients with MDD.