[Effect of the nerve growth factor mimetic GK-2 on post-resuscitation expression of neurotrophic factors].

THE OBJECTIVE: to elucidate an influence of nerve growth factor mimetic GK-2 on the expression of neurotrophic factors and the process of neuronal death after ischemia-reperfusion. Materials and methods. Adult white male rats underwent cardiac arrest for 12 minutes, followed by resuscitation. 10 rats were injected GK-2 (Img/kg i/ρ) at 30 minutes and 48 hours after resuscitation. 10 untreated animals received equivalent doses of saline. The control group consisted of sham-operated animals (n = 10). On the 7th postoperative day the total density of hypoxia-sensitive cerebellar Purkinje cells was determined by morphometric analysis. Immunohistochemical study of proteins FGFb, NT4, BDNF was performed by indirect peroxidase-antiperoxidase method using primary polyclonal antibodies. The number of neurons with different expression levels of the neurotrophic factors was determined. RESULTS: In the post-resuscitation period the neuronal loss was detected in untreated animals. Namely NT4-negative, FGFb-negative and BDNF-negative cells died. GK-2 had no effect on the expression level of FGFb and NT4, however, promoted an increase in the expression level of BDNF. Initiating the expression of BDNF in neurons that were not previously producing this factor, GK-2 prevents the development of post-resuscitation neuronal death. Obtained facts lead to the conclusion that one of the mechanisms of neuroprotective action of nerve growth factor mimetic GK-2 is its ability to activate the expression of BDNF in nerve cells.

Effectiveness of GK-2, a Nerve Growth Factor Mimetic, in Preventing Post-Resuscitation Changes in the Brain.

Neurological status was assessed and the numbers of neurons per 1 mm in pyramidal neuronal layer length in CA1 and CA4 hippocampal fields and cerebellar Purkinje cells were evaluated in albino male rats on post-resuscitation day 14 after 12-min cardiac arrest. Intraperitoneal administration of GK-2 (1 mg/kg 30 min after resuscitation and within the next 3 days with an interval of 24 h) accelerated neurological recovery of the animals, sharply reduced the intensity of cerebellar Purkinje cell death, and prevented loss of pyramidal neurons in the hippocampus. These results show the effectiveness of systemic administration of the nerve growth factor mimetic GK-2 in improving structural and functional state of the brain in the post-resuscitation period. This opens new prospects of its use for prevention and correction of post-hypoxic encephalopathy.

Ca(2+) transport into sarcoplasmic reticulum and immediate-early response proteins in the myocardium of rats resuscitated after systemic circulatory arrest.

Activity of antioxidant defense enzymes and content of stress protein HSP70 in the heart increased in passive and, to a lesser extent, in active rats on day 7 of the postresuscitation period after systemic circulatory arrest. The resistance of membrane structures in the heart to endogenous damaging factors in passive rats was lower than in active animals. The degree of compensation in active rats was much higher than in passive animals at these terms of the postresuscitation period.

Active and passive behavior of animals during the postresuscitation period.

Behavioral reactions (open-field test, elevated plus-maze, pain stress, and feeding behavior) were studied in various periods after clinical death caused by circulatory arrest for 10 or 15 min. We revealed two different phases of behavioral changes: active behavior directed at attaining a specific goal and passive behavior directed towards isolation of the organism from external signals and functional minimization. Active behavior determined by pathological excitation in the central nervous system increased the severity of structural damage to hippocampal CA1 neurons during the postresuscitation period. By contrast, passive behavior and minimization of functions preserved structural integrity in these neurons.

[Postresuscitation cerebral structural and functional changes associated with the initial type of behavior]. / Postreamanitsionnye strukturno-funktsional'nye izmeneniia mozga, sopriazhennye s iskhodnym tipom povedeniia.

The elevated cross-shaped labyrinth test carried out on highly, moderately, and low active experimental animals revealed significant differences in the baseline density and composition of neuroglial populations of numerous formations of the brain, as well as in the early structural and functional sequels of experienced clinical death. The most pronounced postresuscitation abnormal changes were observed in highly active animals and the least marked ones were seen in moderately active animals.

[Development of postresuscitation morphological changes of hippocampal and cerebellar neurons: common regularities and specific features]. / Razvitie postreanimatsionnykh morfologicheskikh izmenenii neironov gippokampa i mozzhechka: obshchie zakonomernosti i osobennosti.

A comparative morphometric study of postresuscitation changes in the neuronal populations of the pyramidal cells from hyppocampal sector CA1 and Purkinje cells of the lateral cerebellar region in the course of postresuscitation period after 12-minute cardiac arrest in rats has shown that the changes differ in severity and pattern. In the pyramidal cells there were reversible dystrophic alterations of the neurons. Purkinje cells showed death of some neurons, this process progressed in the course of postresuscitation period. A positive effect of the peptide kyotorphin on the brain condition after resuscitation was found but its efficacy in different neuronal populations varied.

Mechanisms of adaptation to flow reactions in rats after systemic blood arrest.

The rats survived 10- or 15-min systemic blood flow arrest were exposed to various extreme factors within the following 2 months. It was found that the processes leading to functional isolation of CNS play a protective role: they moderate behavioral response to acute stress and alleviate the degree of neuron damage induced by long-term stress during acquisition of a complex food-procuring reflex.

[Effect sandostatin on functional and structural recovery of the central nervous system after clinical death]. / Vliianie sandostatina na funktsional'no-strukturnoe vosstanovlenie tsentral'noi nervnoi sistemy posle klinicheskoi smerti.

A behavior examination set was used to reveal a decreased anxiety as well as increased locomotor and exploratory activities and changes in resuscitated animals undergoing different learning tests. A single injection of sandostatin--an analogue of regulatory peptide somatostatin--was found to improve the structural and functional recovery of the central nervous system after a 12-minute cardiac arrest.

[Therapy of postresuscitation behavioral disorders with mexidol and kyotorphin]. / Korrektsiia postreanimatsionnykh narushenii povedencheskikh reaktsii meksidolom i kiotorfinom.

A complex of behavioral tests revealed diminished anxiety, increased locomotor and exploratory activities, and changes in different learning tests in resuscitated animals. Mexidol alone and in combination with kyotorphin exhibited antistressogenic and nootropic activities, and led to a compensation of ischemic lesions in rats. It can be stated that a the injection of mexidol in combination with kyotorphin yielded better results due to its neuroprotective effect in the CA1 and CA4 fields of the hippocampus.

[Effect of perftoran on post-resuscitation recovery of the central nervous system]. / Vliianie perftorana na postreanimatsionnoe vosstanovlenie tsentral'noi nervnoi sistemy.

The effect of perfluorane on survival and restorative process in the brain were studied in rats subjected to 12-min arrest of systemic circulation. Perfluorane in a single dose of 5-10 ml/kg was injected intraperitoneally 30 min after the beginning of reanimation. The drug did not affect the postreanimation death of animals and time course of neurologic deficiency disappearance. Perfluorane activated behavioral reactions and prevented development of dystrophic changes in the brain structures of rats highly sensitive to hypoxia.

[Action of neuropeptides on the status of neuronal populations in the post-resuscitation period: structural-functional correlation]. / Deistvie neiropeptidov na sostoianie neironal'nykh populiatsii v postreanimatsionnom periode: strukturno-funktsional'nye korreliatsii.

Effects of some neuropeptides and hormones (oxytocin, melanostatin, oxytocin in combination with estradiol, somatostatin) on neurons of the V cortical layer, Purkinje cells of medial and lateral regions of rat cerebellum were studied in rats after 15 minutes of cardiac arrest. A single administration of the peptides after successful cardiopulmonary resuscitation improved the condition of neuronal populations (prevented dystrophy and cell death), accelerated neurological recovery. One of the mechanisms of action of oxytocin, melanostatin and oxytocin in combination with estradiol is elevated number of satellite glial elements of the nervous tissue. Responses of varying neuronal populations to neuropeptide action are different. These data are essential for design of pathogenetic methods of prevention and treatment of posthypoxic encephalopathies.

[Effects of active behavior in the postresuscitation period on the functional and morphological characteristics of the brain]. / Vliianie aktivizatsii povedeniia v postreanimatsionnom periode na funktsional'nye i morfologicheskie kharakteristiki mozga.

Efficacy of prolonged (days 10-60 after resuscitation) regular activation of behavior by labyrinth training of 4-staged food search conditioned reflex is studied in rats subjected to 15-min circulation arrest. This training affected the function of the central nervous system, which manifested by decreased anxiety and a higher activity in the open field test. This functional exercise prevented fall-out of neurons in the fifth layer of hemispheres, of cerebellar Purkinje's cells, and of pyramidal neurons in hippocampal sector CA1. These results support the hypothesis proposed by A. M. Gurvich on the possibility of regulating the postresuscitation recovery of the central nervous system by neurophysiological treatment of the brain.

[The effect of succinic acid on postresuscitation pathology of the CNS and of the body as a whole]. / Vliianie iantarnoi kisloty na postreanimatsionnuiu patologiiu TsNS i organizma v tselom.

The effect of oral succinic acid was studied in rats exposed to 10-min heart arrest followed by resuscitation. The drug was administered for 5 days in a dose of 30 mg/kg starting from day 3 up to day 7 after resuscitation. Succinic acid was found to normalize the orientation and exploration behavior of rats in the "open field" test, decreased the intensity of response to stress (electric shock), and normalized the radical formation in the brain tissue and blood serum, thus reducing the morphological changes in the brain. In addition, succinic acid prevented the development of risk factors of atherogenesis, namely, increase of the levels of blood cholesterol, triglycerides, and low and very low density lipoproteins. Further studies are needed to validate the addition of succinic acid to the armory of drugs preventing the development of postresuscitation encephalopathies in remote (3 months) periods.

[Changes in heterogenous neuron populations in the postresuscitation period after heart arrest in rats]. / Izmeneniia geterogennykh neironnykh populiatsii v postreanimatsionnom periode posle ostanovki serdtsa u krys.

Morphometric examination of neurons of the Vth layer of the sensorimotor cortex and Purkinje's cells in two functionally different parts of the cerebellum was carried out in various periods after resuscitation in rats exposed to 10 or 15-min heart arrest. General regularities and differences in the reaction of heterogenous neuronal populations on ischemia of various duration were detected. The time course of restructuring of the neuronal populations was traced. A relationship between the detected shifts and the rate of neurological resuscitation of the animals was established. Neurons of various compartments of the brain and various types of cells in the heterogenous neuronal populations were found to be characterized by different sensitivity to ischemia.

[Effects of sodium succinate on functional, biochemical and morphological indicators of CNS repair in rats after 10-minute circulation arrest]. / Vliianie suktsinata natriia na funktsional'nye, biokhimicheskie i morfologicheskie pokazateli vosstanovleniia TsNS u krys posle 10-minutnoi ostanovki krovoobrashcheniia.

Therapeutic effect of sodium succinate on various functional, biochemical, and morphological parameters of CNS repair was studied in experiments on rats exposed to 10-min circulation arrest. The first series of experiments was devoted to studies of the effects of the drug, injected intraperitoneally directly after recovery of effective cardiac activity and during the subsequent 5 days in doses 20, 100, and 200 mg/kg, on the survival and recovery of the external neurologic status. The dose of 20 mg/kg proved to be the most effective. The second series of experiments was devoted to therapeutic effect of sodium succinate in the same dose injected from day 3 to day 7 after revival on the orientation and investigation behaviour in an "open field" test, on changes in radical formation in the blood serum and the brain, and on the cholesterol/lipid ratio in the brain, as well as on the morphologic changes in the cerebral hemispheres and the cerebellum. In contrast to untreated animals, the treated ones had a less intensive reaction in the "open field" test in response to acute stressor exposure, their cerebral and blood serum levels of free radical processes were reduced, the destruction of neuronal membranous elements was less intensive, as were dystrophic changes in the cerebral cortex and the cerebellum. The data permit a conclusion about antistressor and protective effect of sodium succinate in the postresuscitation period at the functional, biochemical, and morphological levels.

[The characteristics of the adaptive behavior, neurological recovery and a morphometric analysis of the cerebral cortex in rats in the postresuscitation period]. / Osobennosti adaptivnogo povedeniia, nevrologicheskoe vosstanovlenie i morfometricheskii analiz kory mozga krys v postreanimatsionnom periode.

Rats recovered after a 10-min circulation arrest, were examined in the early postresuscitation period (within 10-12 days after resuscitation) in an open field (OF) test and during elaboration and reproduction of passive avoidance conditioned reflex (PACR); morphometric analysis of sensorimotor brain cortex was performed on days 4, 7, 14, and 30 after resuscitation. It has been shown that directly after compensation of external neurological deficit which took place in the majority of animals within 3 days the process of adaptation to new situation (OF test) in resuscitated rats, unlike the intact ones, was associated with high motor activity and not with the elaboration of stable correlations between various behavioral acts. At the same time disorders in learning and memory have been observed in PACR test. Morphometric studies have revealed changes in neuroglial relations by day 14 and considerable dystrophic neuronal changes by month 1 after resuscitation. All these disturbances took place with the overall density of neuron population preserved.

[Intensity of protein synthesis in different sections of the brain of rats after arrest of systemic circulation]. / Intensivnost' sinteza belka v razlichnykh oblastiakh mozga krys, perenesshikh ostanovku sistemnogo krovoobrashcheniia.

Protein synthesis intensity in the tissue of various portions of the brain of rats pre-exposed to 10 min systemic circulation arrest was studied with the use of 3H-leucin, a protein synthesis labeled precursor, and compared with that in intact animals. Protein synthesis intensity in the brain of resuscitated animals was found to correlate with the degree of their neurologic status recovery. In rapidly recovering animals a significant intensification of protein synthesis is observed on day 4 after resuscitation in the sensorimotor cortex, hippocampus, and cerebellum. In the animals whose resuscitation was not so smooth this process develops only in the hippocampus and the intermedial and lateral portions of the cerebellum. In patients with disturbed neurologic status protein synthesis intensity was unchanged in all the examined portions of the brain. The authors suggest that protein synthesis activation phase is an obligatory stage in full-value neurologic recovery of resuscitated animals.