[The impact of pregnancy and postnatal period on the development of generalized convulsive activity in experiment].

Interrelation between pregnancy and epilepsy is one of the pressing problems of current neurology. Those mechanisms, which suppress or amplify the seizure reactions in pregnancy, have not been yet determined experimentally. The goal of present work was investigation of impact of gestation and the postpartum period on initiation and development of convulsive reactions in the experimental animal model. Epileptic reactions were significantly suppressed during gestation (2 and 3 weeks). The data showed changes in behavioral reactions and EEG seizure activity. In the period of gestation the development of audiogenic kindling in response to repetitive acoustic stimulation is markedly reduced. This indicates the strengthening of inhibitory processes in the brain. It is supposed that in the period of gestation in rats with genetically determined audiogenic seizures excess of sexual hormones and enhancement of GABA-ergic transmission causes marked reduction of development of audiogenic kindling.

[Influence of solitary tract nucleus stimulation on activity of thalamic reticular nucleus and mesencephalic reticular formation of the brain].

Elucidation of interrelations between the brainstem (BSN) and diencephalic structures of the brain is an important problem of neurophysiology, solution of which might allow revealing mechanisms of the workings of certain structures of the brain, on the one hand, and an overall activity of the central nervous system, on the other. The goal of present investigation was examination of the mechanism of interrelations between the mesencephalic reticular formation (MRF), solitary tract nucleus (STN), and the thalamic reticular nucleus (TRN). Activity of the TRN and MRF neurons was recorded with the tungsten microelectrodes, with tip diameter of 4-8 microm and a resistance of 4-15 MOhm. In some experiments a simultaneous (coupled) recording of the TRN and MRF neurons was made with an aid of two separate microelectrodes. Our experiments have shown that threshold stimulation of the MRF exerted an inhibitory influence on activity of the TRN neurons, while supra-threshold stimulation induced their activation. Stimulation of the STN induced inhibition of the MRF neurons and activation of the TRN. Meanwhile, during activation of the TRN neurons, in the MRF neurons inhibitory postsynaptic potentials did occur. Whatever mechanisms may underlie inhibition of the TRN neurons in response to the STN stimulation, it seems an important fact that synchronizing structure of the brainstem, which exerted a blocking impact on the MRF, facilitated activity of the TNR neurons. This is even more important because for revealing the neurophysiologic mechanisms of activity of the whole central nervous system in both norm and disorder.

[Effects of ultracaine on the local blood flow of the gum and on the development of cerebral seizures in experiment].

We have studied the effect of ultracaine DS forte on local blood flow of the rat gum as well as on the development of the convulsion activity of the brain at systemic injection. Experiments were carried out on 12 mongrel albino mail rats of 200-250 g weight. In the I group of animals under the light chloral hydrate anesthesia we studied the changes of local blood flow in the rat gum of lower jaw after ultracaine DS forte injection (right side) and the similar quantity of phisiological solution (left side). According to our data, in the right gum, the rate of local blood flow decreases statistically significantly at 18%, while the injection of physiological solution did not result in any changes. In the II group, experiments were carried out on the animals with bipolar electrodes in neocortex, as well as in the right and the left dorsal hippocampus. On the fifth day after surgical intervention, on the background of registration of electric activity of the above stated structures 0,03-0,04 ml of ultracaine Ds forte was injected intraperitoneally, which did not result in any significant deviation on the encephalogram. 10-fold doze injection was followed by abortion of epileptic discharges (0,3 ml), but repeated injection of 0,3 ml of preparation resulted in generalized clone-tonus type seizure activity. Simultaneously, clone-tonus type behavioral manifestation was revealed.

[Development of audiogenic kindling during the gestation period].

Some peculiarities of audiogenic kindling were studied in rats with genetically determined epileptic seizures during gestation period. In the period of gestation the development of audiogenic kindling in response to repetitive acoustic stimulation is markedly reduced. This indicates the strengthening of inhibitory processes in the brain. It is supposed that in the period of gestation in rats with genetically determined audiogenic seizures excess of sexual hormones and enhancement of GABA-ergic transmission causes marked reduction of development of audiogenic kindling.

[Peculiarities of development of rat's audiogenic convulsive responses in the period of gestation].

In rats, with genetically determined audiogenic epileptic seizure some peculiarities of convulsive responses before and during gestation as well as after the delivery were studied. Depending on responses to audio stimuli the rats of Krushinsky-Molodkina line might be divided on two groups. The responses of first group are: fear and facial muscles clonus; the responses of other group--fear, wild running and then development of clonic and tonic seizures. The rats of this (second) group were used in our experiments. In the period of gestation: (a) extended latency of development of convulsive activity; (b) significant prolongation of the intervals between wild running and (c) marked reduction of behavioral manifestation of clonic and tonic seizures have been observed. These indicate the strengthening of inhibitory processes in the brain. It is supposed that in the period of gestation in rats with genetically determined to development of audiogenic seizures excess of sexual hormones causes the gaining of anticonvulsive processes in the brain. Evidently, this should be connected with GABA-ergic inhibitory mechanisms of the brain.