Effect of adaptation to intermittent hypoxia on serotonin metabolism and oxidative stress in the hippocampus of rats with experimental post-traumatic stress disorder

Введение. Посттравматическое стрессовое расстройство (ПТСР) формируется спустя длительный срок после переживания психической травмы. Имеются данные о низком уровне серотонина у больных ПТСР, который часто сочетается с окислительным стрессом, обусловленным нейровоспалением. Представляется актуальным поиск эффективных средств немедикаментозной коррекции ПТСР. Одним из высокоэффективных и наиболее широко используемых методов является адаптация к периодической гипоксии (АПГ). Цель работы - исследование влияния АПГ на обмен серотонина и показатели окислительного стресса в гиппокампе животных при экспериментальном ПТСР. Методика. Исследование выполнено на 34 половозрелых самцах крыс Вистар, которые были разделены на 4 группы («Контроль», «ПТСР», «АПГ», «ПТСР+АПГ»). В качестве модели экспериментального ПТСР была использована модель хронического предаторного стресса, где животные подвергались «запаху хищника» (кошачьей мочи) по 10 мин в течение 10 сут. После этого крыс адаптировали к периодической гипоксии в гипобарической барокамере в течение 14 сут, начиная с 30 мин в 1-е сут на симулированной высоте 1000 м, с постепенным увеличением «высоты» и времени экспозиции до 4000 м в течение 4 ч на 5-е сут и в последующие дни. Поведенческие реакции животных изучали при помощи теста «приподнятый крестообразный лабиринт» (ПКЛ). Концентрацию серотонина и его метаболита 5-гидроксииндолуксусной кислоты (5-ГИУК) определяли методом высокоэффективной жидкостной хроматографии. Содержание первичных и вторичных продуктов перекисного окисления липидов (ПОЛ) оценивали спектрофотометрически согласно методике И.А. Волчегорского и соавт. Уровень окислительной деструкции белков оценивали по содержанию карбонилированных белков. Результаты. При тестировании в ПКЛ было установлено, что у животных через 14 сут после завершения предаторного стресса по сравнению с контролем наблюдалось усиление тревожности, которое ограничивалось курсом АПГ. Одновременно с этим установлено снижение содержания серотонина и повышение уровня 5-ГИУК, что привело к существенному повышению метаболического индекса серотонина. Курс АПГ не привел к статистически значимым изменениям содержания серотонина и его метаболита по сравнению с контролем. В группе «ПТСР+АПГ» по сравнению с группой «ПТСР» отмечено повышение концентрации серотонина при одновременном снижении 5-ГИУК и метаболического индекса серотонина. Исследование окислительного стресса в гиппокампе животных с ПТСР-подобным состоянием показало повышение базального уровня карбонилированных белков по сравнению с контролем и увеличение содержания вторичных продуктов ПОЛ. Заключение. При экспериментальном ПТСР в гиппокампе снижение содержания серотонина ассоциировано с усилением его метаболизма, что сопровождается усилением окислительного стресса. Нейропротекторное действие АПГ выражается в нивелировании окислительного стресса в гиппокампе. Background. Post-traumatic stress disorder (PTSD) develops long after a mental traumatic event. In patients with PTSD, low serotonin levels often combine with oxidative stress-induced inflammation. Searching for effective non-pharmacological therapies for PTSD is important. Adaptation to intermittent hypoxia (AIH) is one of highly effective and widely used methods. The aim of this study was to elucidate the effect of AIH on serotonin metabolism and oxidative stress in the hippocampus of rats with PTSD. Methods. The study was performed on 34 sexually mature male Wistar rats divided into 4 groups: control, PTSD, AIH, and PTSD+AIH. Experimental PTSD was modeled with chronic predator stress, where animals were exposed to predator smell (cat urine) for 10 days, 10 min daily. Then rats were conditioned in a hypobaric altitude chamber for 14 days at a 1,000-m simulated altitude for 30 min on day 1 with altitude and duration progressively increasing to 4,000 m for 4 h on day 5 and all the remaining days. Behavioral reactions of rats were studied with the elevated plus maze (EPM) test. Concentrations of serotonin and the serotonin metabolite, 5-hydroxy indole acetic acid (5-HIAA), were measured by high-performance liquid chromatography. Contents of primary and secondary lipid peroxidation (LPO) products were measured spectrophotometrically according to the method of I.A. Volchegorskiy et al. The oxidative damage to proteins was assessed by the content of carbonylated proteins. Results. The EPM test showed that 14 days after the predator stress completion, the anxiety level was higher than in control, and this effect was alleviated by AIH. Also, stress-exposed rats had lower serotonin and higher 5-HIAA concentrations, which resulted in a significantly higher serotonin metabolic index compared to the control. The course of AIH did not cause any significant changes in concentrations of serotonin and its metabolite as compared to the control. In the PTSD + AIH group compared to the PTSD group, the serotonin concentration was increased whereas the 5-HIAA concentration and the metabolic serotonin index were decreased. Studying oxidative stress in the hippocampus of rats with the PTSD-like condition showed that both the basal level of carbonylated proteins and the content of LPO secondary products were increased compared to the control group. Conclusions. In experimental PTSD in the hippocampus, the decrease in serotonin content was associated with the increase in its metabolism and with potentiation of oxidative stress. The neuroprotective effect of AIH was evident as alleviation of oxidative stress in the hippocampus.

Benzodiazepine tranquilizers abolish the stress-induced increase of the brain ghrelin level in DANIO RERIO

Danio reriohas firmly established itself as a successful model for research in many areas of biology and medicine, first of all for developing new medicines. The aimof our study was to evaluate ghrelin level in zebrafish brain after stress and after phenazepam usage on stressed fish. Methods.In our study 96Danio rerio, predatorCichlasoma nicaraguensishave been used. The fish have been kept at anormal room temperature (2223C) with standard feeding time (twice per day). The level of neuropeptides has been tested by ELISA test. During experiment a fish has been firstly placed in a beaker with a dissolved pharmacological substance, then has been transferred into a tank with predator. In the end of experiment, it has been put into a novel tank for 6 min. The decapitation has been made. Thebrain has been divided into three anatomical parts:telencephalonjust behind the olfactory bulb, the middle partcorpora bigemiaandcerebellum, which is situated behind thecorpora bigemia. After that the material for ELISA test was made using GhrelinFISH, MyBioSource ELISA kit. Results.In the control group ghrelin has been determined only in thecerebellumin 57.14% of all fish. In the experiment with predator ghrelin has been found in all tested brain parts of fish, but in thetelencephalonthere was the highest level. Inthe experiment with phenazepam usage only and phenazepam administration after predator stress, the ghrelin value has not been determined atall. Conclusion.Thus we have found out that the ghrelin value increases after predator stress and the drug phenazepam eliminated it completely after its administration. We may suppose that the administration of anxiolytics such as phenazepam can reduce the anxiety inDanio rerio.

Benzodiazepine tranquilizers abolish the stress-induced increase of the brain ghrelin level in DANIO RERIO

Danio reriohas firmly established itself as a successful model for research in many areas of biology and medicine, first of all for developing new medicines. The aimof our study was to evaluate ghrelin level in zebrafish brain after stress and after phenazepam usage on stressed fish. Methods.In our study 96Danio rerio, predatorCichlasoma nicaraguensishave been used. The fish have been kept at anormal room temperature (2223C) with standard feeding time (twice per day). The level of neuropeptides has been tested by ELISA test. During experiment a fish has been firstly placed in a beaker with a dissolved pharmacological substance, then has been transferred into a tank with predator. In the end of experiment, it has been put into a novel tank for 6 min. The decapitation has been made. Thebrain has been divided into three anatomical parts:telencephalonjust behind the olfactory bulb, the middle partcorpora bigemiaandcerebellum, which is situated behind thecorpora bigemia. After that the material for ELISA test was made using GhrelinFISH, MyBioSource ELISA kit. Results.In the control group ghrelin has been determined only in thecerebellumin 57.14% of all fish. In the experiment with predator ghrelin has been found in all tested brain parts of fish, but in thetelencephalonthere was the highest level. Inthe experiment with phenazepam usage only and phenazepam administration after predator stress, the ghrelin value has not been determined atall. Conclusion.Thus we have found out that the ghrelin value increases after predator stress and the drug phenazepam eliminated it completely after its administration. We may suppose that the administration of anxiolytics such as phenazepam can reduce the anxiety inDanio rerio.

c-Fos and FosB/ΔFosB colocalizations in selected forebrain structures after olanzapine, amisulpride, aripiprazole, and quetiapine single administration in rats preconditioned by two different mild stressors sequences

Objective. Olanzapine (OLA), amisulpride (AMI), aripiprazole (ARI), and quetiapine (QUE) belong to antipsychotics, which administration represents still most reliable way for the treatment of schizophrenic and bipolar disorders. The intention of the present study was to explore whether the acute administration of a particular antipsychotic, indicated by the presence of c-Fos, will: a) stimulate neurons already activated by a long lasting homogeneous or heterogeneous stress preconditioning, indicated by the FosB/ΔFosB (ΔFosB) expression, or b) have a stimulatory effect only on a not activated, so called silent neurons. The pattern of ΔFosB and c-Fos spatial relationship was investigated in three forebrain structures, including the septal ventrolateral nucleus (seVL), the striatal dorsolateral area (stDL), and the shell of the nucleus accumbens (shell).Methods. The rats were divided into 10 groups and exposed to two types of stressors. Half of them was exposed to a sequence of homogeneous stressor – handling (HDL) and the other half to a heterogeneous stressor (CMS) daily for 20 days. CMS consisted of five types of stressors: crowding, air-puff, wet bedding, predator stress, and forced swimming applied in an unexpected order. On the 21st day of the experiment, the rats were free of the stress exposure and on the 22nd day, both groups of animals receive a single intraperitoneal injection of vehicle (4% DMSO in saline, 0.1 ml/100 g) or OLA (5 mg/kg), AMI (20 mg/kg), ARI (10 mg/kg), and QUE (15 mg/kg). 90 min after the drugs administration the animals were transcardially perfused, brains removed, cut into 30 µm thick coronal sections, and double stained: first with ΔFosB antibody linked with Alexa488 fluorescent dye and second with c-Fos antibody linked to Alexa596 one. Quantitative evaluation of ΔFosB and c-Fos colocalizations was performed on fluorescence photomicrographs transformed into a final picture containing only yellow, green, and red colored circles.Results. The data of this investigation demonstrate that ΔFosB and c-Fos colocalizations occurred in each of the three areas investigated, i.e. seVL, stDL, and shell ones, in both HDL as well as CMS preconditioned rats. The levels of ΔFosB and c-Fos colocalizations varied in the individual forebrain areas studied. From the total 22 areas measured, level of c-Fos colocalization prevailed over ΔFosB in 18 ones. However, neither c-Fos nor ΔFosB reached 100% level of colocalization in any of the forebrain areas investigated.Conclusion. The present findings indicate that ΔFosB and c-Fos colocalizations occurred in each of the three areas investigated, i.e. seVL, stDL, and shell, in both HDL and CMS preconditioned rats, whereas the parallel occurrence of free c-Fos as well as c-Fos colocalized with ΔFosB might speak out for a possible involvement of the c-Fos activated by antipsychotics applied in dual, i.e. short- and long-lasting, functions.

PHARMACOLOGICAL CORRECTION BY PHENAZEPAM OF DISORDERS IN INTERACTION OF NERVOUS AND IMMUNE SYSTEMS DURING PREDATOR STRESS IN DANIO RERIO

The behavior of Dario rerio fish under stress control (mental trauma modeling) and with the axiolytic drug phenazepam was studied. With the drug phenazepam - tranquilizer fish calm down and float to the top of the aquarium. Typically, this fish was used in research in the field of molecular genetics and developmental biology, but recently it has become attractive in the work on the creation of new drugs and the modeling of various physiological and pathological processes. Danio rerio is a model organism in developmental biology. Most human genes have homologs in zebra fish (70%-80%), and functional kinase domains have 100% identity. The hypothalamic-pituitary-adrenal axis corresponds to that in humans. The aim of our work is to determine the neuropeptides in the brain of Danio rerio after stress effects and the use of phenazepam.

Quercetin attenuates acute predator stress exposure-evoked innate fear and behavioral perturbation

Background Oxidative stress plays a pivotal role in the pathophysiology and pathogenesis of mental diseases, such as depression or anxiety. Psychological stress induced by predatory stimulus is one of the models that explain how induced affective behavior is manifested as a depression-like state. Quercetin is a flavonoid that exhibits potential pharmacological activity on mental diseases. Thus, the present study was designed to investigate the effect of quercetin on innate fear and affective behavior induced by repeated predator stress exposure on mice. Materials and methods ICR mice were exposed to predatory stress for 3 days. Quercetin at a dose of 50 mg/kg was given intraperitoneally along with stress induction. The freezing behavior during the stress induction was analyzed. The anxiety-like and depressive-like behaviors and cognitive and motor functions were examined on the last day of induction. Results Predatory stress increased the affective behaviors (anxiety-like and depressive-like behaviors) and produced freezing behavior without alterations in the cognitive function and exploratory behavior. Treatment with quercetin 50 mg/kg attenuated the freezing, anxiety-like and depressive-like behaviors. Conclusions Repeated predator stress exposure causes both innate fear and depression-like state for the prey animals. Quercetin may have a protective effect against depression and alleviates the fear of traumatic events.

Anxiety and neurometabolite levels in the hippocampus and amygdala after prolonged exposure to predator-scent stress

Here, to study the relationship between anxiety levels with changes in the neurometabolic profile in the hippocampus and amygdala, an experimental predator stress model was reproduced in which Sprague-Dawley rats were exposed to cat urine for 10 minutes on a daily basis for 10 days. At the time of presentation of the stimulus, an online survey of behavioral reactions was conducted. Fear, aggressiveness, avoidance of stimulus and grooming were recorded. Fourteen days after the completion of the last stress exposure, the total level of anxiety was determined in the test of the“cross maze”. Using the method of in vivo NMR spectroscopy, the content of neurometabolites was determined in the hippocampus and in the amygdala. According to the peculiarities of behavioral reactions to a stressor, animals were retrospectively divided into two phenotypes. The first phenotype used a passive behavioral strategy, and the second phenotype was active. In animals of the first phenotype, the indicators of anxiety behavior remained at the control level. In animals of the second phenotype, a decrease in anxiety was observed. Animals of the second phenotype showed elevated levels of lactate in the hippocampus compared to animals of the first phenotype, and the lowest N-acetylaspartate levels significantly differed from those in the control and the first phenotype animals. In the amygdala, in animals of the second phenotype, the content of taurine is sharply reduced in comparison with those in the control and the animals of the first phenotype. Thus, the results obtained indicate a relationship of post-stress changes in anxiety, with the peculiarities of the behavioral reactions presented at the moment of the immediate action of the stressor. Among the hippocampal and amygdala neurometabolites, the most informative for the characterization of the anxiolytic action of the predator stress are identified.