Search

Abstract The Nissl method and immunocytochemistry were used to study the effects of severe hypobaric hypoxia and its actions in combination with the preconditioning actions of moderate hypoxia on the expression of the early gene proteins c-Fos and NGFI-A as well as structural changes in hippocampal and neocortical neurons in the rat brain. Severe hypoxia was found to suppress c-Fos and NGFI-A synthesis (324 h after exposure) and to induce delayed (days 37) structural damage to neurons, of the light and predominantly the dark types, which appear to reflect the development of necrotic and apoptotic processes respectively. Preconditioning with the regime used here corrected these derangements, resulting in increases in the expression of early gene proteins and significant reductions in structural damage to neurons after severe hypoxia. [ABSTRACT FROM AUTHOR]

Abstract In the 25-day old rats there were studied effects of prenatal serotonin (5-HT) depletions and stress on pain sensitivity evaluated using formalin test by indexes of the biphasic behavioral response (BBR)-the number of flexions and shakings as well as duration of licking of the formalin injected leg, duration of the first and second response phases and on morphofunctional characteristics of the brain structures involved in BBR. The 5-HT depletion (a single intraperitoneal injection of parachlorophenylalanine, an inhibitor of 5-HT synthesis, to pregnant females at the initial period of development of the serotoninergic system) produced morphological lesions in the neocortex areas and hippocampus and raphe nuclei, which were accompanied by an essential decrease of the pain sensitivity (until its complete inhibition) during the second, tonic, BBR phase. In the prenatally stressed rats (immobilization of pregnant females for the last pregnancy week) with prenatal 5-HT depletion the nerve cell death in the above brain structures was accompanied by an increase of the pain sensitivity revealed by all response indexes during the second, tonic phase, whereas in the prenatally stressed rats developed without the intervention into the serotoninergic system, only one index was found to increase. The obtained results indicate that 5-HT participates in formation of the tonic nociceptive system and in mediation of effects of the prenatal stress on the pain sensitivity to the long-term nociceptive stimulus. [ABSTRACT FROM AUTHOR]

Elaboration of the conditional reflex reaction of passive avoidance was studied in the 42–46-day old offsprings of two groups of female rats: intact (control) and exposed to action of hypoxia at the 13th, 16th or 19th day of pregnancy. The parameter of learning was the time of stay of the rats in a dark camera, in which they obtained an electroshock. It is shown that the prenatal hypoxia has different effect on the ability to elaborate the conditional reflex reaction of passive avoidance in female and male rats. By this parameter, no differences were revealed in the male group between the control and the animals exposed to hypoxia at different terms of intrauterine development. In female exposed to hypoxia at the 19th day of gestation, it was not possible to elaborate the conditional reflex reaction of passive avoidance. In females exposed to hypoxia at the 13th day of gestation the parameters of learning were lower, whereas in the females exposed to hypoxia at the 16th gestation day they were higher than in control animals. [ABSTRACT FROM AUTHOR]