[Oxygenation of the frontal cerebral cortex in monkeys during a two-week space flight]. / Kislorodnyi rezhim lobnoi kory golovnogo mozga obezíany v protsesse 2-nedelnogo kosmicheskogo poleta.

In monkeys (Macaca mulatta) during a two-week space flight and in a ground-based control experiment, with semi-closed platinum electrodes, partial oxygen pressure (pO2) was registered in the frontal cerebral cortex. It was shown that during the flight there is a marked increase of pO2 in the frontal cortex, reaching maximal values on days 5-8 (up to 203%) with a subsequent tendency to normalization by day 11. In the control experiment pO2 values in the cortical zone studied did not exceed the baseline level throughout the period of registration. Analysis of the curves of pO2 oscillations in the frequency range from 0.2 to 0.01 Hz in-flight revealed a shift of the oscillation power spectrum in the long-wave direction which was not seen in the control experiment and suggested a decreased rate of tissue metabolism. As a possible explanation for the noted effects of pO2 dynamics during weightlessness, a combination of a decreased metabolic rate in the brain segment under study with a disorder in the mechanism of regulation of local cerebral blood flow is suggested.

[Mechanisms of enkephalin action on learning and memory processes]. / O nekotorykh mekhanizmakh deistviia énkefalinov na protsessy obucheniia i pamiati.

The influence of enkephalin on the processes of elaboration and preservation of the defensive conditioned reflexes of bilateral avoidance (CRBA) and conditioned reflexes of passive avoidance (CRPA) in intact rats and animals with changed functional state of serotoninergic system of the brain has been examined. Injection of enkephalin in dose of 10 mkg to intact animals accelerated the elaboration of CRBA not influencing in this case their preservation, but deeply disturbed the CRPA preservation. The excess of serotonin in the brain created by means of 5-oxytryptophan fully prevented the acceleration of CRBA elaboration by enkephalin under the usual conditions. Injection of enkephalin at the background of serotonin lowering and raising in the brain favoured CRBA preservation. Under the enkephalin influence the inclusion of [3H]tyrosine and [14C]lisine in water-soluble and water-insoluble proteins of different cerebral structures lowered. The obtained data testify to participation of serotoninergic system and brain proteins in the mechanisms of enkephalin action to the processes of learning and memory.