[Changes in background activity of periaqueductal gray neurons through application of serotonin or inhibition of its synthesis]. / Izmenenie fonovoi aktivnosti neironov tsentral'nogo serogo veshchestva pri podvedenii k nim serotonina ili blokade ego sinteza.

Application of serotonin (ST, 1.10(-4) M to periaqueductal grey neurons influenced background activity (BA) only in the third group of cells. In 45.5% of them ST evoked depression of BA. Through application of ST remarkable potentiation of BA inhibition evoked by locus coeruleus (LC), substantia nigra (SN) stimulation was found, but inhibitory affects of nucleus raphe magnus (NRM) were less intensive. After intraperitoneal injection of p-chlorophenylalanine the efficiency of NRM stimulation became lower, but influences of LC and SN on BA increased. The mechanisms of serotoninergic effects on BA of periaqueductal grey neurons are discussed.

[Modulation of periaqueductal gray neuronal activity by influences of brain stem monoaminergic structures]. / Moduliatsiia aktivnosti neironov tsentral'nogo cerogo veshchestva srednego mozga vliianiiami monoaminergicheskikh struktur stvola.

Studies of spontaneous firing (SF) in the midbrain periaqueductal gray (PAG) neurons before and after stimulation of nucleus raphe magnus, locus coeruleus and substantia nigra were performed on the rat anesthetized with Hexenal (200 mg/kg). Three types of neurons different in SF structure were found. Stimulation of indicated structures increased SF rate in 11-14.5% and decreased 31-47% of the studied neurons of the third group. Simultaneous stimulation of two structures did not induce a remarkable increase of SF rate. If one of two simultaneously stimulated structures suppressed SF the ultimate effect was, as a rule, depression of SF. Greatest suppression of SF was observed if stimulation of nucleus raphe magnus was induced. Role of PAG in organization of the brain stem component of antinociceptive mechanism is discussed.

[The hypothesis of acupuncture points as polymodal receptors of the ecoceptive sensitivity system]. / Gipoteza o tochkakh akupunktury kak polimodal'nykh retseptorakh sistemy ékotseptivnoi chuvstvitel'nosti.

Hypothesis is proposed that the human brain has the sensory system (ecoceptive sensory system) which responds to changes of the Earth electromagnetic fields (EEFs) and meteorologic factors (MFs). Acupuncture points which are activated easily by adequate somatosensory stimuli (mechanical, temperature) and electromagnetic fields (electropuncture, magnetopuncture) can be polymodal receptors of the ecoceptive sensory system. It is supposed that the sensory endings of acupuncture points are excited by sharp changes ef EEFs and MFs. Through the neuronal brain stem structures, especially through hypothalamus, acupuncture points excitation starts the adaptive mechanisms intended to compensate the brain functional systems deviations, provoked by prolonged EEFs and unsettled weather environmental influences.

[The effect of creatine phosphate on reflex transmission in the normal spinal cord and under hypoxic conditions]. / Vliianie kreatinfosfata na reflektornuiu peredachu v spinnom mozge v norme i v usloviiakh gipoksii.

The effect of phosphocreatine on reflex transmission in the spinal cord was studied in rats in vivo and in vitro. Low concentrations (10(-8)-10(-6) M) of phosphocreatine facilitated while high concentrations (10(-4)-10(-3) M) inhibited the amplitude of mono- and polysynaptic reflexes. It was found that phosphocreatine decreases the inhibiting action of hypoxia on test responses and accelerates restoration of the reflex transmission in the spinal cord.

[Effect of electric stimulation of auricular acupuncture points on H-reflex]. / Vliianie élektrostimuliatsii aurikuliarnykh akupunkturnykh tochek na H-refleks.

The non-nociceptive H-reflex in the musculus soleus were recorded before and after auricular electroacupuncture (AEAP) in patients with vertebrogenic pain syndrome. Changes of the H-reflex on the side of the pain syndrome were observed after ipsi- and contralateral AEAP, the latter producing effect more often. Changes of H-reflex are mainly of facilitating character (71.4%) and, rarely, of inhibitory character (14.3%). In the part of patients AEAP produced distinct facilitation of M-response.

[Modulation of the nociceptive flexor reflex by the electrostimulation of auricular acupuncture points]. / Moduliatsiia notsitseptivnogo sgibatel'nogo refleksa élektrostimuliatsiei aurikuliarnykh akupunkturnykh tochek.

Nociceptive flexor reflex (NFR) in patients with vertebrogenic lumbosacral pain syndromes was recorded before and after the ipsi- and contralateral auricular electroacupuncture (AEAP). Changes in NFR were observed after ipsi- and contralateral AEAP, each producing facilitatory and inhibitory effects on NFR. Facilitatory influence of AEAP on NFR correlated with hypalgesia, that apparently reflected recovery of the afferent input peculiarities.

[Changes in somatosensory evoked potentials in patients with vertebrogenic pain syndromes treated by electroacupuncture]. / Izmeneniia somatosensornykh vyzvannykh potentsialov u bol'nykh vertebrogennymi bolevymi sindromami pod vliianiem elektroakupunktury.

Application of electroacupuncture (EAP) of the segmental points to patients with vertebrogenic algesic syndromes decreased amplitude of N150 and P240 waves recorded from vertex to painful electrocutaneous stimulation in the region innervated by an affected root. As distinct from EAP of segmental point auricular EAP not only decreased the amplitude of late components of evoked potentials (EP), but also increased it, direction of EP changes depending on the character of sensitivity disorders. It is suggested that effect of EAP-evoked EP changes in patients with hypalgesia is determined by two oppositively acting factors: by a decrease of nociceptive afferent impulsation intensity as a result of the antinociceptive system activation and by an increase of the afferent impulsation intensity due to recovery of function of central terminals in primary sensory neurons.

[Basic principles of the functional organization of the nociceptive and antinociceptive systems of the brain]. / Osnovnye printsipy funktsional'noi organizatsii notsitseptivnykh i antinotsitseptivnykh sistem mozga.

Adequate estimation of situations which evoke a damage of tissues and defence of functional systems of the organism from excessive nociceptive influences can be achieved in the case when the brain structures take part in nociception and form a developed complex of the specialized and closely interconnected neuronal systems (nociceptive, analgesic and antianalgesic ones).

[Role of the serotoninergic system in inhibiting the jaw-opening reflex induced by stimulation of the central gray matter of the midbrain]. / Rol' serotoninergichekoi sistemy v tormozhenii refleksa otkryvaniia rta, vyzvannom stimuliatsiei tsentral'nogo serogo veshchestva srednego mozga.

Effect exerted by stimulation of the central grey matter (CGM) of the midbrain and nucleus raphe dorsalis (nRD) by a short train of stimuli (20) followed with the rate of 400/s on the high-threshold jaw-opening reflex (HJOR) evoked by electrical irritation of the tooth pulp was studied during serotonin synthesis blockade after parachlorphenylalanine (pCPA) administration (300 mg/kg intraperitoneally) in awake cats. It was found that the inhibitory effect of the CGM and nRD stimulation on HJOR decreased 24 hours after the pCPA injection. Inhibition of HJOR induced by CGM and nRD stimulation became minimal 96 hours after the pCPA administration: reflex magnitude decreased only by 33% and duration of inhibition was 200-250 ms. Conclusion is made about serotonin participation in HJOR depression induced by CGM and nRD stimulation. The possible participation of other neuromodulators in such inhibition is discussed.

[The effect of stimulation of the substantia nigra on low- and high-threshold startle reflexes in the cat]. / Vliianie stimuliatsii chernoi substantsii na nizko- i vysokoporogovyi refleksy vzdragivaniia u koshek.

Effects of the substantia nigra (pars compacta) stimulation on two functional types of startle reflexes were studied in chloralose-anesthetized cats. The reflexes were the low-threshold ones evoked by tactile stimuli (T-reflex) and high-threshold ones evoked by intense peripheral nerve stimulation (spino-bulbo-spinal, SBS reflex). It was found that substantia nigra stimulation exerted mainly inhibitory influences on both types of reflexes. However the depression of the SBS-reflex was always more profound and long lasting (up to 8 min) than that of T-reflex. The latter reflex was sometimes facilitated.

[The effect of stimulation of the substantia nigra on the low- and high-threshold neuronal responses of the reticular formation]. / Vliianie stimuliatsii chernoi substantsii na nizko- i vysokoporogovye otvety neironov retikuliarnoi formatsii.

Modulation of somatosensory responses of bulbar (n. reticularis gigantocellularis) and pontine (n. reticularis pontis caudalis) reticular neurons by the substantia nigra (SN) stimulation was studied in cats under light chloralose anesthesia. It was found that the action of the SN stimulation on the somatosensory activity of the neurons was based on the principle of the inhibitory control of their high-threshold synaptic somatosensory inputs; high-threshold neuronal responses were much more depressed than the low-threshold ones in most (71%) of the studied reticular units. Possible neuromodulatory mechanisms and functional significance of described influences are discussed.

[Influence of stimulation of the central gray matter on low- and high-threshold startle reflexes]. / Vliianie stimuliatsii tsentral'nogo serogo veshchestva na nizko- i vyusokoporogovye refleksy vzdragivaniia.

Influences of the periaqueductal gray matter (PAG) stimulation on high-threshold jaw opening reflex (JOR) evoked by tooth pulp stimulation and on two functional types of startle reflexes were studied in chloralose anesthetized cats; the startle reflexes were high-threshold ones evoked by intense peripheral nerve stimulation (spino-bulbo-spinal, SBS, reflex) and low-threshold ones evoked by tactile stimuli (tactile spino-reticulo-spinal, TSRS, reflex). Stimulation of the majority of PAG sites induced considerable inhibition of JOR as well as profound depression of SBS-reflexes and moderate depression of TSRS-reflexes. Some PAG sites were found to exert a facilitatory action on the latter reflex. Effects of PAG stimulation were short-term (hundred ms) and/or long-lasting (minutes). Possible mechanisms of these effects are discussed.

[Effect of the stimulation of the central gray substance of the midbrain on the neuronal responses of the trigeminal caudal nucleus during peripheral excitations]. / Vliianie stimuliatsii tsentral'nogo serovogo veshchestva srednego mozga na otvety neironov kaudal'nogo iadra spinal'nogo troinichnogo trakta pri perifericheskikh razdrazheniiakh.

Experiment on cats under chloralose-nembutal anaesthesia has shown that 65% responses of caudal trigeminal nucleus neurons to the activation of the tooth pulp, A alpha and/or A delta infraorbital nerve afferents were completely suppressed by conditioning stimulation of the central grey matter (CGM) by a train of stimuli (10-20) that followed with the rate of 200-400/s, if the interval between conditioning and testing stimuli did not exceed 100 ms. Conditioning stimulation of the CGM inhibited responses of the "convergent" neurons to the activation of tooth pulp most efficiently (0.76) and those to the activation of A alpha afferents more weakly (0.6). Effectiveness of "high-threshold" neurons inhibition under the effect of CGM stimulation was 0.71 and that of "low-threshold" neurons--0.48. Ten caudal trigeminal nucleus neurons were activated by the CGM stimulation with the latency of 7.5-20 ms. These neurons did not respond to peripheral nerve stimulation for 200-450 ms after CGM activation. A possible role of caudal trigeminal nucleus neurons in the CGM inhibition of jaw opening reflexes is discussed.

[Effect of stimulation of the central gray substance on the low- and high-threshold responses of the reticular neurons in the pons and medulla oblongata]. / Vliianie stimuliatsii tsentral'nogo serogo veshchestva na nizko- i vysokoporogovye otvety retikuliarnykh neironov mosta i prodolgovatogo mozga.

The modulation of somatosensory responses of bulbar (n. reticularis gigantocellularis) and pontine (n. reticularis pontis caudalis) reticular neurons by electrical stimulation of periaqueductal gray matter (PGM) was studied in cats under light chloralose anaesthesia. PGM points which evoked the inhibition of nociceptive jaw opening reflex were stimulated. It was found that in most cases (88%) the PGM stimulation had an inhibitory effect on both nociceptive and non-nociceptive responses of reticular neurons. For bulbar cells with predominant high-threshold inputs nociceptive responses were depressed much stronger than non-nociceptive ones and in pontine neurons for which low-threshold inputs were predominant non-nociceptive responses were inhibited mainly. The data suggest that the inhibitory action of PGM stimulation on somatosensory activity of reticular neurons are based on the principle of the "control of their main synaptic input".