Postresuscitation Changes in Brain Free Radical-Mediated Processes and Nitric Oxide Synthase Activity in Rats: Effects of Individual Behavior in "Emotional Resonance” Test

Effects of 7-min cardiac arrest and individual behavior on free radical-mediated processes and nitric oxide synthase (NOS) activity was evaluated in brains of male Wistar rats one hour and one week after resuscitation. "Emotional resonance test was used for the behavioral selection of rats. The test includes factors of significance for rats: the choice between large and lighted or small and dark space as well as signals of pain of another rat. Free radical generation (using chemiluminescence method), superoxide scavenging/generating activity, substances reacting with 2-thiobarbituric acid and NOS activity (by measuring mononitrosyl iron complex of NO with diethyl dithiocarbamate and endogenous brain Fe²⁺ by electron spin resonance spectroscopy) were determined in cerebral cortex, cerebellum and hippocampus. Cardiac arrest induced oxidative stress accompanied by the loss of NOS activity, as well as compensatory changes of free radical-mediated processes in cerebral cortex. Oxidative stress was also evident in cerebellum and, to a lesser extent, in hippocampus. Most of neurochemical differences between behavioral groups were induced by cardiac arrest. These differences were global, related to a specific brain region or became apparent in cerebral lateralization of biochemical indices.     

The delayed effects of systemic circulatory arrest on the free-radical processes in the brain structures of rats with different types of behavior in the emotional resonance test]

Male Wistar rats with different types of behavior in "emotional resonance" test ("active" and "passive") were studied one week after the global ischemia induced by cardiac arrest. Recovery of some physiological functions as well as free-radical-mediated processes and NO-synthase activity were studied in cerebral structures and blood serum. The "open-field" behavior normalized more rapidly in the "active" rats than in the "passive" ones, though the time course of the neurologic deficit compensation did not differ in these groups. A decrease in superoxide scavenging activity and in the content of 2-thiobarbituric acid-reactive material was revealed in the cerebral structures of both "active" and "passive" rats. Increased levels of free-radical generation in the hippocampus of the "passive" rats and in the cerebellum of the "active" rats were found. Higher NO-synthase activity was demonstrated in the cerebellum of the "passive" rats. Taken together, these data suggest that there are specific patterns of free-radical-mediated processes in the brain of rats with different types of behavior in "emotional resonance" test.     

The dynamics of the brain heat fields of rats in the late postresuscitation period during stress]

By thermoencephaloscopy method the temperature relief of the rats cerebral cortex was studied after the clinical death and reanimation. The rehabilitation of the animals neurological status was completed in 1-2 days. In the remote postresuscitation period (up to 2 months), expressed disturbances were revealed of the background thermomaps and of thermal reactions of the cerebral hemispheres, evoked by the stress influence. Pathologic mosaics of thermal characteristics was revealed in conditions of relative rest and disturbance of dynamics of the brain temperature reactions and the character of interhemispheric asymmetries at stress influence. Individual character is pointed out of postreanimative pathology, which is manifest both in the background thermomaps and after the functional load. The results of the studies suggest the importance of individual approach in rehabilitation therapy of postreanimative disease.     

The indices of rat open-field behavior and the characteristics of the survival and functional recovery of the CNS following circulatory arrest

In experiments on rats it has been shown that for prognostication of successful reanimation after the clinic death of different duration (5, 10, 15 min) correlative interactions between the parameters of behaviour in the open field before blood circulation cessation are more essential than their absolute values. Highly significant correlation coefficients (0.7 and more) between the majority of behaviour parameters were typical for the group of animals which had survived after a prolonged blood circulation cessation (15 min); for rats rehabilitated after 5- and 10-min cessation of the blood circulation--between the characteristics reflecting, basically, the motor-investigating component of the behaviour. In groups of died animals (independently on the duration of clinic death) correlation profile was restricted to characteristics determining only the character of the motor activity. Particular significance is underlined of emotionally psychic components of the behaviour for complete CNS restoration after a prolonged blood circulation cessation in comparison with the shorter ones.     

Morphofunctional evaluation of the condition of the brain in rats with different degrees of recovery of neurological status following arrest of systemic blood circulation

The brain status was studied for four days after resuscitation of rats with different degrees of recovery of the neurological status after systemic circulatory arrest induced by the occlusion of vascular bundles of the heart. Morphometric analysis of the population of Purkinje cells from the two different functional zones of the cerebellum revealed that in comparison with completely recovered rats, the animals with disturbed neurological status were characterized by loss of neurons, disturbed composition of the neuronal population, development of severe dystrophic cell changes. The lateral zone of the cerebellum hemisphere was most affected. Four days after resuscitation all the animals showed a sharp increase in the size of the nucleus of Purkinje cells, which is considered to be one of the mechanisms of neuronal adaptation to hypoxia.