engleski

The influence of nimodipine and MK-801 on the brain free arachidonic acid level and the learning ability in hypoxia-exposed rats

A number of reports indicated that a disturbance in calcium homeostasis induced by hypoxia is accompanied with increase in free arachidonic acid (FAA) level and behavioral deficits. The purpose of this study was to investigate the effects of calcium channel blockers, nimodipine and MK- 801 on the brain FAA level and learning ability in hypoxia-exposed rats. The study was carried out on Hannover-Wistar rats weighing 250 g. They were injected with 0.03 ; 0.1 ; 0.3 or 1 mg/kg of tested drugs. Thirty minutes later the learning ability was tested in a passive avoidance task according to the step-through procedure. Immediately after the training trial, the animals were subjected to a period of oxygen deprivation hypoxia until the loss of the righting reflex. The retention trial was carried out 24 hours later. A part of animals was pretreated with calcium channel blockers tested and exposed to the hypoxic conditions. Fifteen minutes after losing the righting reflex they were decapitated and brains were frozen in liquid nitrogen. The FAA was separated by thin- layer chromatography, methyl esters were prepared by methanolysis and quantified by gas chromatography. The level of FAA was measured. It has been found that nimodipin was effective in reversing the significant increase of the brain FAA level and memory decline in hypoxia-exposed rats. MK-801 prevented the accumulation of the brain FAA, but did not improve the memory deficit in hypoxic animals.

nimodipine; MK-801; free arachidonic acid; hypoxia; brain; rat

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