HYPOTHALAMIC CONTROL OF THE ACTIVITY OF DEITERS' NUCLEUS NEURONS

The excitatory and inhibitory tetanic and post-tetanic changes of lateral vestibular nucleus (LVN) of Deiters' single neurons pulse flow frequency activity evoked by high frequency stimulation of hypothalamic Paraventricular (PVN) and Supraoptic (SON) nuclei was revealed. Depressor effects might be assumed of both true inhibitory and/or disfacilitatory origin. Producing depression from the brain higher endocrine centers is important for prevention of possible intensification of vestibular tonus alongside with exclusion of flexor-extensor balance, which is controlled by motor centers of the brain. The existence of excitatory reaction indicates to delicate regulatory action of PVN and SON to LVN as well. By means of Ca2+-dependent acidic phosphate method there were shown big polygonal LVN neurons, with dichotomized distant branching from the cell body and high activity of enzymes in dendrites and around the nucleus. By horseradish peroxydase (HRP) transport method the retrograde labeled large cells were shown in the medial and ventral parts of SON. Projecting to LVN small labeled source-cells unlike the large cells were predominantly revealed in dorsal and medial divisions of PVN. There were also found transient and anterograde marked preterminals The direct bilateral connections of LVN with PVN and SON indicate that LVN acts not only as an integrative structure, coordinating and controlling different motor actions concerned with regulation of posture and orientation in space, but is also involved in the processes of central regulation on autonomic functions.