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Biomedical subjects

R V Sarukhanian

Publications and source records attributed to R V Sarukhanian.

9 recordsLinked to original sources
PubMed1999

[The role of various parts of the amygdaloid complex in the regulation of activity of respiratory neurons].

In microelectrophysiological investigations influences of different nuclear regions of the amygdaloid complex on the spike activity of the functionally identified single respiratory neurons of the medulla oblongata were studied in anesthetized cats. It was established a qualitative different character of the changes of unit activity of the medullary respiratory neurons in case of stimulation of phylogenetically old corticomedial or new basolateral nuclear groups of the amygdala. It was shown higher reactivity of the investigated neurons to stimulation of the corticomedial nuclei than basolateral. The influences of the corticomedial nuclear groups on the bulbar inspiratory and expiratory neurons were facilitatory as well as inhibitory with prevailing excitatory effects. It was found that influences of the phylogenetically new neoamygdaloid structures of basolateral region on spike activity of the bulbar respiratory neurons differ accordingly to their topographical differentiation. Mechanisms of amygdaloid control of activity of the medullary respiratory neurons are discussed.

Amygdala↗
PubMed1987

[Mechanisms of the suppression of the nociceptive reflex of the opening of the mouth during stimulation of the structures of the limbic brain].

The comparative effectiveness of the inhibitory influence of tetanic stimulation of hypothalamus, amygdala and limbic cortex on EMG-response of m. digastricus evoked by electrical stimulation of tooth pulp nociceptive afferents was studied in cats anesthetized with a mixture of chloralose and nembutal. It was found that inhibition of the EMG-component of the jaw-opening reflex is most pronounced in case of stimulation of medial and lateral region of the hypothalamus, the inhibitory effect of central and medial nuclei of the amygdala is less pronounced and the effect of the limbic cortex is the weakest. It was shown that the mechanism of the antinociceptive effect of tetanic stimulation of the hypothalamus is not related to the concomitant increase of the blood pressure. After stabilization of the blood pressure the suppressive effect of the hypothalamus remains without changes, that points out to a direct, primary, not baro-afferent mechanism of the inhibition of the activity of nociceptive neurons of the trigeminal sensory nuclei. Noradrenaline, injected intravenously, induced a large increase of the blood pressure accompanied by a pronounced inhibition of the pain reflex. Angiotensin causes the same degree of blood pressure elevation without changes in the amplitude of the EMG-response of the pain reflex. Hypothalamic and noradrenergic mechanisms for control of pain sensitivity are discussed.

Action Potentials↗
PubMed1987

[Discharges in the white rami communicantes evoked by stimulation of different fields of the limbic system].

Electrical responses to stimulation of different areas of the cingulate gyrus were studied in L2-L3 white rami in anesthetized and immobilized cats. The stimulation evoked a sympathetic discharge mostly consisting of a wave with a mean latency of 71.2 +/- 2.3 ms. In a few cases, the main wave was preceded by a short-latency component. Thresholds for eliciting sympathetic discharges were lower in case of stimulation of the ventral region of area 25 in comparison to those of the dorsal region of the same area. A comparative study showed that the lowest were the thresholds of hypothalamic evoked discharges, somewhat higher were the thresholds of amygdala stimulation and the highest were those of the cingulate cortex evoked discharges. In experiments with simultaneous recording of arterial pressure and cingulo-sympathetic discharges, after 10-sec period of tetanic (100/sec) stimulation of the limbic cortex, the early components were facilitated while the late component of the cingulo-sympathetic discharges was depressed. The duration of this inhibition corresponded to the period of pressure reaction and, therefore, was of a baroreceptor origin. Possible mechanisms of cingulate cortex regulation of the activity of sympathetic preganglionic neurons, are discussed.

Amygdala↗
PubMed1987

[Comparative study of sympathetic and parasympathetic discharges in the autonomic nerves during stimulation of different structures of the cat hypothalamus].

Simultaneous recordings of hypothalamo-parasympathetic and hypothalamo-sympathetic evoked discharges in anesthetized cats demonstrated that both parasympathetic discharges in the pelvic nerve and sympathetic discharges in the splanchnic nerve of the lowest threshold and shortest latency could be obtained from stimulation of the posterior hypothalamus. The focus of the maximal neuronal activated elicited by stimulation of afferent fibres of visceral nerves and the focus evoking maximal efferent reactions of parasympathetic and sympathetic nerves were located in the same region of the postero-lateral hypothalamus. It is supposed (as a working hypothesis) that convergent polysensory neurons of the hypothalamus are also polyeffector divergent elements of the hypothalamo-visceral reflex system.

Action Potentials↗
PubMed1985

[Evoked hypothalamic potentials from the pelvic nerve].

Comparative electrophysiological analysis of EPs in the posterior, tuberal and anterior hypothalamus to electrical stimulation of the pelvic nerve was performed in anesthetized and immobilized cats. The focus of maximal activity was revealed in the postero-lateral hypothalamus. "Visceral" responses of the hypothalamus evoked by the pelvic nerve stimulation had a long recovery cycle and were suppressed at a low-frequency stimulation. These findings suggest a poly-synaptic organization of the projection of pelvic afferent systems in the hypothalamus.

Afferent Pathways↗
PubMed1984

[Reactions of the neurons of the bulbar respiratory center area to microiontophoretic application of opiate substances and serotonin].

Morphine, codeine and serotonin (5-HT) were microelectrophoretically applied to inspiratory, expiratory and unspecific reticular neurons located in the region of the bulbar respiratory center in anesthetized cats. Opiate agonists exerted distinct inhibitory effects on inspiratory, expiratory and inspecific neurons. With 5-HT inhibition prevailed in all three types of neurons. The inhibitory effects of GABA were more profound and prolonged in comparison with the depressing effects of opiate agonists and 5-HT. The latters depressed peak frequency of each rhythmic burst of respiratory neurons, while GABA abolished the rhythmic activity. The existence of specific opiate and 5-HT receptors in neurons of the bulbar respiratory center region is discussed.

Action Potentials↗
PubMed1982

[Microionophoretic study of the effect of various neurotransmitters on the activity of neurons in the bulbar respiratory center].

Three putative neurotransmitters (L--glutamate--L--GL; GABA and noradrenaline--NA) were applied to bulbar respiratory neurons and for comparison, to unspecific cells. L--GL induced excitation in all tested inspiratory, expiratory and unspecific neurons of the bulbar respiratory area. GABA depressed the firing of respiratory and unspecific neurons. Stimulation of NA receptors resulted in neuronal activation or inhibition with prevailing excitatory effects for all three types of the neurons. Two types of NA-specific receptors seem to exist among the respiratory and nonrespiratory neurons of the bulbar region of dorsal and ventral respiratory areas.

Action Potentials↗
PubMed1980

[Specialization of the descending sympatho-activating pathways of the dorsolateral funiculus of the spinal cord].

In anesthetized curarized cats the degree of specialization of the descending sympathoexcitatory axons which activate sympathetic preganglionic (vasomotor) B2--neurons of the lateral horn, was studied. These sympathoexcitatory fibers with conduction velocity of 4.0--8.9 m/sec activate especially onlg the sympathetic B2--units of the spinal cord. Other neurons (phrenic and intercostal mofoneurons and sacral parasympathetic preganglionic neurons) are activated by different groups of descending fibers with conduction velocity greater than that of descending sympathoexcitatory fibers.

Animals↗