engleski

Vulnerability of the CA1 subfield of the hippocampus in hypoxic and ischemic conditions in rats

The brain has a high metabolic rate, but low oxygen stores and small reserves of high-energy phosphates and carbohydrates. Therefore, it is very sensitive to hypoxia and ischemia, that constitute important, basic pathophysiological mechanisms of brain damage. It is well documented that selective vulnerability of various brain regions exists in hypoxic or ischemic conditions. Moreover, recent reports strongly suggest that hippocampal pyramidal neurons of the CA1 subfield are extremely vulnerable to hypoxia/ischemia that often results in irreversible damage and neuronal death. The purpose of this study was to investigate the influence of hypoxia/ischemia on the integrity of the hippocampal neurons of CA1 region. The study was carried out on Hannover- Wistar rats, weighing 250 gr. One group of the animals was subjected to a period of oxygen deprivation hypoxia. Namely, the rats were placed into the hypoxia cage and the percentage of oxygen was gradually reduced and continuously measured. The level of 3.5 V% of oxygen was reached in about twenty minutes and maintained up to the loss of righting reflex. The second group of the animals was anesthetized with pentobarbital sodium (50 mg/kg, i.p.). Right common carotid artery was occluded and unilateral cerebral ischemia was produced. Seven days after described experimental procedures the brains were perfused transcardially with 10% formalin under pentobarbital anesthesia, according to the technique of Wolf (1971) . The removed brains were postfixed, dehydrated and embedded in paraffin using standard procedures. Coronal sections, 6 m thick, were stained with hematoxylin and eosin. The number of neurons per 1 mm linear length stratum pyramidale (neuronal density) of the hippocampal CA1 subfield was counted and compared with the results of the control group (intact animals). The preliminary results of our study show that hypoxia does not influence, but unilateral occlusion of common carotid artery produces statistically significant decrease in pyramidal cells density of CA1 hippocampal region.

hypoxia; ischemia; hippocampal neurons; rat

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