The changes in the nervous structures under the chemical sympathectomy with guanethidine.

The process of sympathectomy of white rats was achieved by injecting guanethidine intraperitoneally every day for 5.5 weeks at doses of 75 mg/kg of animal's weight. This process of sympathectomy was checked according to ganglion cervicothoracicum neurocytes state. The material was taken on days 1, 14, 30, 90 and 180 after cessation of guanethidine injections. It was ascertained that full sympathectomy under prolonged injections of high doses of guanethidine is reached at 5-6 months after the cessation of the injections, though pronounced total degeneration of gnl. stellatum neurocytes is marked on the 14th-30th days after cessation of the guanethidine injections. The following gradient of damaging influence of guanethidine was revealed: sympathetic gnl. cervicothoracicum neurocytes gnl. nodosum afferent neurocytes-neuromuscular synapsis skeletal muscle.

Static tilt may modify the value of nystagmus asymmetry.

In awake pigeons (Columba livia) we investigated the horizontal cervical and ocular nystagmuses which were induced by monaural stimulation of the lateral semicircular canals by the parathreshold sinusoidal currents. The value of nystagmus asymmetry (by the average velocities of slow components) with a normal orientation of the bird's head was compared with that in static head tilts in the sagittal and frontal planes. In the normal head position depolarization of the lateral canals evoked a stronger response than hyperpolarization of an equal value indicating that Ewald's second law is justified for the weak suprathreshold stimuli. It was found that the static tilts modify the value of nystagmus asymmetry. These changes are connected with the asymmetric modifications of the otolithic activities in tilts. This feature of the canal-olithic interaction should be taken into consideration in estimation of the results of the caloric test one of the obligatory conditions of which is static tilt.

[The metasympathetic mechanisms supporting the constancy and stability of the internal environment in vertebrates]. / Nekotorye metasimpaticheskie mekhanizmy podderzhaniia postoianstva i ustoichivosti vnutrennei sredy pozvonochnykh.

The data were obtained with the aid of extracellular recording of unit activity in the cardial, enteral and respiratory parts of the metasympathetic nervous system, staining of the neural tissue preparations of atrial walls, intestine and lower part of the guinea pig trachea. The neurons were shown to be very sensitive to the main homeostatic contants: pH of the perfusion solution, its temperature and the grade of oxygenation. These structures were shown to take a direct part in maintenance of the constancy and stability of the organism inner milieu. Sympathetic nervous system differs from the above system in that the former is the system of transmission, defence, mobilisation of resources which is necessary for active interaction of the organism with ambient milieu.

[The interaction of vestibular inputs with differing orientations of the otoliths in a gravitational field]. / Vzaimodeistvie vestibuliarnykh vkhodov pri razlichnoi orientatsii otolitov v gravitatsionnom pole.

In alert pigeons Columba livia effects of static tilts about fore-aft and binaural axes (angles of tilts: 30-40 deg) on neck and ocular nystagmus elicited by monaural galvanic stimulation of the lateral semicircular canals with sinusoidal currents (peak amplitudes: 20-100 microA; period: 35 sec) were investigated. It was shown that the same angles of the tilts elicited different changes of horizontal nystagmus parameters in different animals. In some of them changes of quantitative characteristics of opposite-directed nystagmus differed with signs. Data support the correctness of recently (Stolbkov, 1989) proposed scheme of forming vestibulomotor reactions, according to which signals from heterolateral vestibular nuclei, during nystagmus, which are integrated, contain both canal and otolith components independent of stimulus mode addressed to canals or otoliths (separately or jointly). Results suggest also that caloric test may be a source of incorrect conclusions concerning state of vestibular system during static tilts the responses of functionally asymmetric semicircular canals may be symmetric ones. Moreover data suggest that sensitivity of convergent vestibular neurons to the canal signals is different depending on separated or combined canal and otolith stimulations.

[Effect of microelectrophoretic application of GABA on the formation of a cellular analog of a conditioned reaction]. / Vliianie mikroélektroforeticheskoi applikatsii GAMK na formirovanie kletochnogo analoga uslovnoi reaktsii.

Influence of GABA application on ability of sensorimotor cortical neurones to form conditioned cellular reactions was studied in chronic experiments on rabbits. Neuronal reactions were analysed at the initial stage of eye-lid conditioning. GABA application in a period of presentation of paired conditioned and unconditioned stimuli disturbed formation of inhibitory conditioned cellular reactions and did not influence elaboration of activating responses. Plastic changes underlying the process of formation of inhibitory conditioned neuronal reactions are supposed to be of intracortical nature.