[The role of the somatosensory cortex in the development of reflex analgesia]. / Znachenie somatosensornoi kory golovnogo mozga v razvitii reflektornoi analgezii.

The effects of reflex stimulation on the changes of nociception thresholds in animals before and after ablation of the somatosensory cortex were studied in behavioural experiments on adult cats. Electroacupuncture stimulation (EAP) was shown to increase nociception thresholds at all levels of the conventional scale. The ablation of both the first (S1) and the second (S2) somatosensory cortex led to EAP inefficiency at the side opposite to the ablation. Partial lesion of the lateral and suprasylvian gyri, used as control, did not affect the efficiency of reflex analgesia. It is concluded that somatosensory areas of the cortex, especially 2, are involved in reflex analgesia.

[Somatosensory evoked potentials and their dynamics among trigeminal neuralgia patients during reflexotherapy]. / Somatosensornye vyzvannye potentsialy i ikh dinamika u bol'nykh nevralgiei troinichnogo nerva v protsesse refleksoterapii.

The study of somatosensory evoked potentials (SSEP) in patients with trigeminal neuralgia made it possible to elucidate their characteristic changes as compared to those in healthy subjects. After a course of acupuncture 75% of the patients showed correlation between some parameters of SSEP and positive clinical results. The authors discuss pathophysiological mechanisms of impairment of cortico-subcortical interactions in patients with trigeminal neuralgia and analyze the possibility of using SSEP for dynamic evaluation of the brain status in the process of treatment.

[Functional architectonics of neuronal antinociceptive mechanisms during the electroacupuncture method of reflex action]. / Funktsional'naia arkhitektonika neironal'nykh antinotsitseptivnykh mekhanizmov pri élektroakupunkturnom sposobe reflektornogo vozdeistviia.

The peculiarities of neurone bioelectric activity of sensory thalamic nuclei under electroacupuncture (EAP) stimulation have been studied in acute experiments on cats. EAP stimulation has been established to change spontaneous and evoked activity of neurones of sensory thalamic nuclei, that testifies to the development of a new functional state. The functional state of the cortex, in particular the second somatosensory region has been shown to determine the nature of neurone activation of sensory thalamic nuclei during the EAP stimulation. Schemes of possible organization of functional pools realizing the mechanisms of inhibition of nociceptive signals on central neurones during EAP way of reflex stimulation are suggested.

[Modulating influence of the 2d somatosensory cortex of the cerebral cortex on the effects of electroacupuncture on the trigeminal nuclei]. / Moduliruiushchee vliianie vtoroi somatosensornoi oblasti kory bolshikh polusharii mozga na éffekty élektroakupunktury v trigeminal'nykh iadrakh.

The effect of reversible functional inactivation of the second somatosensory cortex of the cerebral hemispheres on changes in the transmission of the afferent signals in the trigeminal nuclei after electroacupuncture was studied in acute experiments on adult cats anesthetized with hexenal (59 mg/kg i. p.). After functional inactivation of the second somatosensory cortex electroacupuncture failed to facilitate the evoked potentials in the oral trigeminal nucleus by stimulation of the tooth pulp and the lip of the mouth. In the caudal nucleus, the inhibitory effect of electroacupuncture on noxious stimulation decreased. The involvement of this brain cortex in the mechanisms of action of electroacupuncture on functionally different nuclei is discussed.

[Effect of electroacupuncture and morphine on evoked potentials in the oral and caudal trigeminal nuclei in the cat]. / Vliianie élektroakupunktury i morfina na vyzvannye potentsialy v oral'nom i kaudal'nom trigeminal'nykh iadrakh koshki.

Electroacupuncture effects on the functions of the oral and caudal trigeminal nuclei were comparatively analyzed in acute experiments on cats narcotized by hexinal (50 mg/kg). Responses evoked in the caudal nucleus by tooth pulp stimulation were inhibited while responses to mouth mucosa stimulation remained unchanged. In the oral nucleus responses to both types of stimulation were relieved. The same results were obtained in an experiment with systemic injection of morphine (5 mg/kg). It is suggested that different parts of the caudal nucleus are responsible for the transmission of discriminative and diffuse components of the nociceptive signals to the specific and nonspecific projection systems. The oral nucleus may be involved in the transmission of signals about mouth lesions conveying the necessity for defense reactions.

[Effect of morphine on the change in the nociceptive and non-nociceptive evoked potentials in the orbitofrontal and secondary somatosensory areas of the cerebral cortex in different functional states]. / Vliianie morfina na izmenenie notsitseptivnykh i nenotsitseptivnykh vyzvannykh potentsialov v orbitofrontal'noi i vtoroi somatosensornoi oblastiakh kory golovnogo mozga pri ikh razlichnykh funktsional'nykh sostoianiiakh.

The effect of morphine on alterations in nociceptive and non-nociceptive evoked potentials (EP) elicited in the second somatosensory (S2) and orbito-frontal cortex of the brain was studied in acute experiments on cats. Administration of morphine in a dose of 5 mg/kg to the above-mentioned structures caused an increase in the amplitude of EP to non-nociceptive stimulation and a decrease of EP to nociceptive stimulation. Under alternate functional inactivation of the orbito-frontal cortex and S2 a unidirectional effect of the projection cortex on the associative orbito-frontal cortex was observed, manifested by a decrease of EP in the orbito-frontal cortex. Administration of morphine with the S2 cooled led to further decrease of EP followed by their restoration in the orbito-frontal cortex, in response to both nociceptive and non-nociceptive stimulation. Meanwhile administration of morphine, with the orbito-frontal cortex cooled, elicited the response in the S2 analogous to that observed after administration of morphine with intact orbito-frontal cortex: a decrease of EP to nociceptive stimulation and an increase of EP to non-nociceptive stimulation. It is suggested that the S2 plays an important role in control of nociceptive and non-nociceptive input to the CNS.

[Features of the neuronal organization of the periaqueductal gray substance of the midbrain in the cat]. / Osobennosti neironnoi organizatsii periakveduktal'nogo serogo veshchestva srednego mozga koshki.

On the basis of morphological investigations two areas were distinguished in the periaqueductal grey of the cat midbrain: medial, directly surrounding the sylvius aqueduct and containing small neurons with significant (P less than 0.001) prevalence of fusiform cells and lateral with larger neurons, where triangular cells were significantly (P less than 0.001) prevalent. The neurons of the medial area displayed a significant (P less than 0.001) tendency of their dendrite orientation towards the sylvius aqueduct.

[Reflexogenic changes in the spontaneous and evoked activity of the parafascicular neurons in the rat thalamus during electroacupuncture stimulation]. / Reflektornoe izmenenie spontannoi i vyzvannoi aktivnosti neironov parafastsikuliarnogo kompleksa talamusa koshki pri élektroakupunkturnoi stimuliatsii.

Acute experiments on cats were made to study the electroacupuncture (EAP) effect on neuronal impulse activity in the parafascicular complex (PFC) of the thalamus in response to solitary peripheral nociceptive and non-nociceptive stimuli. EAP stimulation affects the pattern of spontaneous and evoked activity of PFC neurons and forms their new functional status. It is suggested that the analgetic effect is brought about by the changes in neuronal activity in subcortical structures of the brain including the thalamic nuclei which transmit the ascending nociceptive input.

[Role of the somatic monoaminergic systems in the mechanisms of regulation of pain sensitivity during reflex stimulation]. / Izuchenie roli monoaminovykh sistem organizma v mekhanizmakh reguliatsii bolevoi chuvstvitel'nosti pri nekotorykh vidakh reflektornogo razdrazheniia.

Experiments on rats were performed to study the role of the monoaminergic systems in the mechanisms of analgesia produced by stress (foot shock) and auricular electroacupuncture (AEA). Analgesia was measured by the hot-plate (HP) and the tail-flick (TF) tests. Inhibition of catecholamine synthesis with alpha-methyl-p-tyrosine (alpha-MPT) antagonized the AEA-induced analgesia measured by the TF test. alpha-MPT did not influence the HP test latency after AEA, and HP or TF tests after stress. Inhibition of dopamine receptors by haloperidol produced a decrease in the stress- and AEA-induced analgesia. The similar effects were demonstrated in propranolol treated rats after AEA. P-chlorophenylalanine (an inhibitor of serotonin synthesis) suppressed the stress-induced analgesia measured by the HP test and AEA-induced analgesia measured by the HP or TF tests. The data indicate that the monoaminergic systems are involved in the stress- and AEA-induced analgesia. Apart from the monoaminergic systems, other neurochemical mechanisms are also involved in the stress- and AEA-induced analgesia.