Behavioral response and erythrocyte chromophilia of rats in experimental traumatic brain injury

Введение. Патогенетические основы изменения микроциркуляции крови в головном мозге вследствие черепно-мозговой травмы (ЧМТ) изучены не в полной мере по причине высокой инвазивности нейроморфологических методов. Цель исследования - изучение поведенческого статуса и информативности цитохимических критериев хромофилии эритроцитов в качестве маркеров вазореактивности микрососудов головного мозга при черепно-мозговой травме у крыс. Методика. Объектом исследования являлись 3-месячные аутбредные крысы Wistar массой 250-270 г. Легкую и средней тяжести ЧМТ воспроизводили с применением модифицированной модели падающего груза для взрослых крыс. Через 2 ч, 1, 2, 8 и 14 сут после моделирования ЧМТ проводили неврологическое обследование животных по модифицированной шкале Neurological Severity Scores (mNSS), сенсомоторное - по степени тревожности в тесте «свет-темнота», поведение анализировали с использованием теста условной реакции пассивного избегания. С помощью хромаффинной реакции исследовали функциональное состояние эритроцитов. Срезы тканей головного мозга, окрашивали по Нисслю и гематоксилин-эозином, микроскопировали, проводили морфометрию цифровых изображений. Результаты. Неврологическое обследование при среднетяжелой ЧМТ показало очаговую симптоматику, соответствующую выраженным неврологическим расстройствам, тогда как после ЧМТ легкой степени у крыс отмечались незначительные нарушения координации. В тесте условной реакции пассивного избегания на 7-е сут у этих животных выявлено состояние повышенной тревожности. Морфометрический анализ препаратов головного мозга травмированных животных показал уменьшение диаметра просвета капилляров и выявил признаки гипоксии нейронов. Цитохимическая оценка эритроцитов, с привлечением количественного определения степени флуоресценции, выявила особенности окислительного метаболизма в клетках у травмированных крыс. Эти показатели коррелировали с морфологическими признаками гипоксии головного мозга. Заключение. В начальный посттравматический период отмечено уменьшение диаметра просвета капилляров нервной ткани, наличие морфологических признаков компенсации нейронов, что является локальной ответной реакцией клеток на ишемию головного мозга. В капиллярах определяется нарушение гемореологии, что является следствием изменения окислительно-восстановительных процессов вследствие гипоксии при внутричерепной травме. The pathogenetic basis of changes in blood microcirculation in the brain due to traumatic brain injury (TBI) has not been fully studied due to the highly invasive nature of neuromorphological methods. Aim: To study the behavioral status and informative value of cytochemical criteria for erythrocyte chromophilia as markers of cerebral microvessel vasoreactivity in rats with TBI. Methods. The study was conducted on 3-month-old Wistar albino, outbred rats weighing 250-270 g. Mild to moderate TBI was simulated using a modified falling weight model for adult rats. At 2 hrs, 1, 2, 8, and 14 days after TBI, a neurological examination was performed according to the modified Neurological Severity Score (mNSS) modified scale and a sensorimotor examination was performed according to the degree of anxiety in the light-dark test. Behavior was analyzed using the conditioned passive avoidance response test. The functional state of erythrocytes was studied using the chromaffin reaction. Brain tissue samples stained by Nissl and with hematoxylin-eosin were evaluated under a microscope, digital images were obtained, and morphometric processing was performed. Results. Neurological examination after moderate TBI showed focal symptoms corresponding to severe neurological disorders, while after mild TBI, rats had minor coordination disorders. In the conditioned passive avoidance response test on the 7th day, the rats showed a state of increased anxiety. Morphometric analysis of the brains showed a decrease in the diameter of capillary lumen and changes in neurons, indicating signs of hypoxia. The cytochemical assessment of erythrocytes, involving a quantitative determination of the degree of fluorescence, revealed features of cell oxidative metabolism in injured rats. Moreover, these indicators correlated with morphological signs of hypoxia in brain neural tissue. Conclusion. In the initial post-traumatic period, there was a decrease in the capillary lumen diameter of the brain neural tissue and the presence of morphological signs of neuronal compensation, which is a local response of cells to cerebral ischemia. Disorders of hemorheology were found. These changes were a consequence of altered redox processes due to hypoxia after intracranial injury.

INFLUENCE OF SODIUM THIOPENTAL ON CONSERVATION OF CONDITIONAL REFLEX OF PASSIVE AVOIDANCE IN RATS WITH DIFFERENT NERRVOUS SYSTEM EXCITABILITY

A study of the dynamics of preservation of the conditioned reflex of passive avoidance (passive avoidance response) in rats of two lines with different level of excitability of the nervous system was performed: with a high and low thresholds of excitability as normal and after exposure to sodium thiopental semi-lethal dose. It was shown that a long preservation of the memorable trace under standard conditions and a higher sensitivity to the sodium thiopental action manifest in rats with a high excitability threshold in comparison with low-excitable line of rats.

p-Hydroxybenzyl Alcohol, an Active Phenolic Ingredient of Gastrodia elata, Reverses the Cycloheximide-Induced Memory Deficit by Activating the Adrenal Gland in Rats

The present study investigated the ameliorating effects of p-hydroxybenzyl alcohol (HBA), an active phenolic ingredient of Gastrodia elata, on cycloheximide (CXM)-induced impairment of passive avoidance response and clarified the role of adrenal glands on the effect of HBA in rats. An adrenalectomy (ADX) caused the memory deficit from 1 to 3 days after surgery. Administration of corticosterone (CORT) plus glucose completely recovered the memory deficit caused by ADX, and this effect was better than that of glucose or CORT alone. HBA ameliorated the memory deficit induced by CXM in sham and ADX rats, but ADX partially blocked it. Furthermore, plasma glucose, epinephrine and adrenal steroid levels of ADX rats significantly decreased. Sham rats who received HBA had an increase in plasma glucose and adrenal steroid levels. Therefore, we suggest that the reversal of CXM-induced memory deficit by HBA was partially dependent on adrenal glands through the increase of the levels of plasma adrenal steroids.

Analysis of neuroprotective effects of polyprenols in a rat model of posttraumatic stress disorder

The purpose of investigation was to assess protective action of polyprenols (2 and 10 mg/kg) in a rat model of posttraumatic stress disorder (PTSD). PTSD was reproduced in situation of unavoidable vital stress in rats by replacing them into a cell with hungry piton. For the five first minutes the piton was separated from the rats with transparent wall to get acquainted each other with a situation. Then, the wall was elevated, and piton seized a rat, asphyxied it when other rats (22) observed at the situation. The majority of rats were collected in the corner dying away from the beast. The other rats behaved themselves differently. Some of them attacked the piton, bited it, but the majority raced chaotically on the cell with piton. The exposure of rats with piton was 20 minutes. For that time it seized and asphyxied 1 or 2 rats. Polyprenols (from 8 till 18 isoprene units) were injected i. p. in doses of 2 or 10 mg/kg in oil solution for 7 days beginning with 1st day of the experiment (the first injection was 1 h after psychogenic exposure). The behavioral reactions were assessed in open field, elevated plus maze, in Porsolt’s test and in one trial passive avoidance response. The effects of polyprenols of 2 and 10 mg/kg were different. Polyprenols 2 mg/kg did not change horizontal and vertical motor activity in rats, moderately (in 1.5-fold) decreasing explorative activity and increasing grooming in open field. Emotional reactions were not changed. In the elevated plus maze, polyprenols 2 mg/kg possessed mild anxiolytic activity performed in 2.5-fold elevation of hangings number. In Porsolt’s test on depression, polyprenols 2 mg/kg moderately increased time of active swimming and sharply decreased time of immobilization (up to zero). That indicated on antidepressant properties of this dose (2 mg/kg) of polyprenols. In passive avoidance test, psychogenic stress facilitated formation and storage of habit (only 10 % of rats entered the dark chamber in 24 h after formation of the habit compared with 60 % in naïve rats). Polyprenols 10 mg/kg moderately activated explorative behavior without any effect on motor activity. In the elevated plus maze, the effects of polyprenols 2 and 10 mg/kg were similar in general. In Porsolt’s test, polyprenols 10 mg/kg did not perform a significant antidepressant effect. At last, in passive avoidance test, 30 % of rats have not learned after psychogenic stress, and the learned rats reproduced the passive avoidance response with phenomenon of hypermnesia, as in control group. So, polyprenols 2 and 10 mg/kg possess anxiolytic and antidepressant activity in a rat PTSD model. Polyprenols 2 mg/kg are more effective than polyprenols 10 mg/kg.

THE STUDy OF THE NEUROPSyCHOPHARMACOLOGICAL EFFECTS OF THE NEW DERIVATIVE OF GLUTAMIC ACID, THE RGPU-197 COMPOUND

Proceeding from the proposition about the high productivity of the search of neuropsychotropic substances among the derivatives of natural neuromediators, a study of neuropsychopharmacological effects of the derivative of the glutamic acid, RGPU-197 compound was carried out. The study was carried out on the he-rats of the Wistar line using the following tests: “open field”, elevated plus maze, conditioned passive-avoidance response, the test of extrapolational deliverance, the test of hanging mice by tails; and also the methods of statistic analysis: rank univariate analysis of Cruscal-Wallace, the Dunn multiple comparison test /the multiple comparison test of Dunn, the x2 criterion. The RGPU-197 compound significantly (p<0,05, p<0,01) decreases the duration of immobilization of the animals and expands the latent period of its approach in the test of hanging mice by tails — it possesses antidepressant activity; increases the quantity of the visits of the centre of the open field, the quantity of attendings of the open hoses of elevated plus maze and the time of stay in them — it shows anxiolytic action; increases the quantity of crossed squares in the open field and the quantity of crossings between the hoses of elevated plus maze — it possesses activating effect; during the displays of the avoidance reflex it expands the latent period of the first period of entering the dark compartment and the quantity of enterings of it in conditioned passive-avoidance response, reduces the latent period of diving under in the test of extrapolational deliverance — it shows nootropic action. According to the intensity of antidepressant action RGPU-197 doesn’t yield to melipramin, anxiolytic and activating effects significantly (p<0.05) excels phenibutum and doesn’t yield to it by nootropic activity. Thus, the new derivative of glutamate, the RGPU-197 compound, possesses the marked antidepressant, anxiolytic and activating effects, as well as nootropic activity.