[Effect of prolonged post-tetanic potentiation on the activity of mediator metabolism enzymes in the hippocampus of rabbits]. / Aktivnost' fermentov mediatornogo obmena v gippokampe krolikov pri dlitel'noi posttetanicheskoi potentsiatsii.

The activity of acetylcholinesterase (AChE) and monoaminoxidase (MAO) in the field CA3 of rabbit's hippocampus was studied with histochemical methods during prolonged posttetanic potentiation (PTP), evoked by short (20 s) low-frequency (20/s) stimulation of n. septo-fimbrialis. Studies were conducted 20 min (group I) and 60 min (group II) after tetanization. In the group I a decrease in AChE activity was observed, especially in str. pyramidale and in the adjacent region of str. oriens. In the group II AChE activity increased, mostly in the external part of str. radiatum. MAO activity increased in both animal groups. For the group I a low (r = 0,42), but significant (P less than 0.05) correlation between PTP value and change in response to AChE was discovered. The reduction of activity 20 min after tetanization may be due to non-specific effect of tetanization as such and to a relatively short posttetanic depression. The increase in MAO activity is interpreted as an indirect confirmation of the part of the monoaminoergic systems in stabilization of plastic rearrangements elicited by tetanization.

[Acetylcholinesterase activity in visual cortex structures during early visual deprivation]. / Aktivnost' atsetilkholinésterazy v strukturakh zritel'noi kory pri rannei svetovoi deprivatsii.

By means of quantitative histochemical methods it has been shown that an early photic deprivation (animals kept in a dark chamber for two months after their birth) leads to a decrease in the activity level of acetylcholinesterase (AChE) in the visual area of the cerebral cortex. With the recovery of the visual function (animals kept in normal photic conditions for two weeks) the AChE activity becomes markedly normalized. The obtained data allow to suggest that the decrease in AChE activity due to deprivation is functionally determined.

[Glutamate dehydrogenase activity in motor cortex neurons during restoration of disrupted visual function]. / Aktivnost' gliutamatdegidrogenazy v neironakh dvigatel 'noi kory pri vosstanovlenii narushennoi zri tel 'noi funktsii.

The recovery of the visual function of rats throughout two weeks after deprivation period (keeping animals in dark chambers for 8 weeks from their birth) leads to a significant normalization of the activity level of glutomatedehydrogenase in the neurones of the III and V layers of the motor cortex. The changes of the enzyme activity in the neurones are accompanied by a diminution of their sizes. The obtained data together with the results of the previous studies (Busnuk, 1976), suggest that the elimination of the visual impulse activity in the early ontogenesis exerts a specific and reversible influence on the morpho-chemical differentiation of neurones both in the visual and in the motor cortical areas. The functional factors determining the direction of changes in the studied parameters of cortical neurones during deprivation and in the rate of their normalization during recovery of the visual function are discussed.

[Changes in glutamate dehydrogenase activity in the neurons of the motor cortexof the cerebral hemispheres during light deprivation]. / Izmenenie aktivnosti glutamatdegidrogenazy v neironakh dvigatel'noi oblasti kory bol'shikh polusharii pri svetovoi deprivatsii.

It has been shown that early light deprivation (keeping the rats for eight weeks from birth in a dark chamber) produces compensatory changes in the majority of pyramidal neurones in layers III and V of the brain motor area: significant enhancement of glutamatdehydrogenase activity activity in the bodies and processes of the neurones, increase of their volumes, augmentation of the number of neuroglial satellites with a high ferment activity. The revealed morphochemical changes, more pronounced in the layer V, are considered as a manifestation of enhanced functional activity of the coritcal end of the motor analyser, resulting from visual dereceptation.

[Several biochemical signs of loss and restoration of visual function]. / O nekotorykh biokhimicheskikh priznakakh utraty i vosstanovleniia zritel'noi funktsii

With the aid of cytophotometry the author studied the cellular chemistry of neurons (according to the activity of glutamate dehydrogenase) in the III, IV and V layers of the visual cortex in rats during the period of rehabilitation of specific functions following long-term light deprivation. It was demonstrated that a 2-week stay of deprivated animals in conditions of usual light is accompanied by visible normalization of the glutamate dehydrogenase activity in the cortical neurons. However, a complete rehabilitation of the control level was not attained. The study demonstrated differences in the reactions of identical neurons in the IV and V layers to the rehabilitation of specific functions. It is being assumed that the rehabilitation of the visual function may be due to biochemical reconstructions in the monomodel and certain parts of the polymodal neurons in the visual cortex.

[Changes in the neurons of the lateral geniculate body under the effect of prolonged darkness (cytochemical study)]. / Izmeneniia neironov naruzhnogo kolenchatogo tela pod vliianiem dlitel'nogo prebyvaniia v temnote (tsitokhimicheskoe issledovanie)

With the aid of the cytospectrophotometry method the author studied the influence of light deprivation (the exposure of animals to darkness during 8 weeks following birth) on neurons of the dorsal nucleus of the external geniculate body of rats according to the index of glutamatedehydrogenase activity. It was established that unlike the visual cortex, separate groups of neurons which react differently to light deprivation, the majority of nervous cells in the external geniculate body demonstrate similar changes: a drop in the medium activity of glutamatdehydrogenase in neurons and its neurological satellites, a shift of neuron histograms according to this index to the left. These changes are accompanied by an increase of smaller neurons as compared to normal, as well as a drop in the amount of neurons with satellites. The found differences of reactions to light deprivation between the cortical neurons and switch areas of the visual analyzer are discussed in the light of functional traits of such neurons.