[The dependence of the effects of naloxone on the type of nociceptive stimulus]. / Zavisimost' éffektov naloksona ot vida notsitseptivnogo stimula.

The dynamics of latent periods of the tail-flick reaction in response to thermal nociceptive stimulus (TNS) and electrocutaneous nociceptive stimulus (ENS) was studied in Wistar rats. Naloxone, 1.4 and 2.8 mg/kg, intraperitoneally injected evoked analgesia in response to TNS and hyperalgesia in response to ENS. It is suggested that the bidirectional effects of naloxone are associated with the specificity of nociceptive mechanisms activated by different pain stimuli.

[Nociceptive sensitivity of rabbits in varying localization of pain stimuli and naloxone administration]. / Notsitseptivnaia chuvstvitel'nost' krolikov pri razlichnoi lokalizatsii bolevykh stimulov i vvedenii naloksona.

Study of the dynamics of changes of evoked potential (EP) amplitude in electrodental and electrocutaneous stimulation (EDS and ECS, respectively) as an index of the perceptual component of the nociceptive reaction showed that 0.2 mg/kg and 0.5 mg/kg doses of naloxone produce both a hyper- and an analgesic effect in rabbits. The effect of naloxone depended on the individual properties of the rabbits, while its degree was determined by the localization of the nociceptive stimulus. The animals' individual properties were manifested by the presence or absence of an analgesic effect of auricular electrostimulation--acupuncture-sensitive (AS) or acupuncture-resistant (AR) rabbits. Naloxone injection caused a dose-dependent hyperalgesic effect in AS animals and an analgesic effect in AR rabbits in EDS. Similar effects were recorded in ECS, but their degree differed: hyperalgesia in AS rabbits was demonstrated more clearly than analgesia in AR animals.

[Clinical and experimental analysis of the use of the Analgedent electrostimulator for dental analgesia]. / Klinicheskii i éksperimental'nyi analiz primeneniia élektrostimuliatora "Analgedenta" dlia dental'nogo obezbolivaniia.

Clinical studies and animal experiments have demonstrated an antinociceptive effect of auricular electrostimulation (AE), 15 Hz, 300 microA, 25 min, on toothache. Perceptual and emotional vegetative components of the painful reaction were reduced by AE in 60 percent of patients and 64 percent of animals. Intravenous naloxone (0.2 mg/kg) abolished AE analgetic effect. The absence of AE analgetic effect in 40 percent of patients and 36 percent of animals can be explained by individual features of the endogenic opioid system functioning. Prospects of AE clinical application with various stimulation frequencies are discussed.

[Effects of auricular electrostimulation and naloxone on nociceptive sensitivity in rabbits]. / Vliianie aurikuliarnoi élektrostimuliatsii i naloksona na notsitseptivnuiu chuvstvitel'nost' u krolikov.

Auriculo-acupuncture electrostimulation (AES) (15 H2) decreased the amplitude of somatosensory evoked potential (EP) in response to tooth pulp electrostimulation in 64% of acupuncture-sensitive unanesthetized rabbits and didn't induce the changes of EP in 36% of animals (acupuncture-resistant rabbits). The systemic naloxone (0.2 mg/kg) injection reversed the AES analgetic effect and induced the hyperalgesic one in acupuncture-sensitive rabbits but induced the analgetic effect in acupuncture-resistant animals. It has been suggested that the differences of individual characteristics of endogenous opioid system determined different naloxone action in acupuncture-sensitive and acupuncture-resistant rabbits.

[Selective analgetic effects of angiotensin and bombesin during the action of dental and cutaneous nociceptive irritants]. / Izbiratel'nost' analgeziruiushchikh éffektov angiotenzina i bombezinapri deistvii dental'nykh i kozhnykh notsitseptivnykh razdrazhitelei.

In non-anesthesized rabbits intraventricular injection of angiotensin II reduced the amplitude of somatosensory evoked potential to nociceptive tooth pulp, but not to nociceptive electrocutaneous stimulation. The same injection of bombesin induced the contrary analgetic effect. The systemic naloxone (0.1 mg/kg) injection didn't reverse the peptides analgetic effects. It's suggested that selective analgetic effects of angiotensin II and bombesin are determined by the presence of the specific different peptide mechanisms for nociception with the different pain genesis.

[Effect of angiotensin II and naloxone on the nociceptive sensitivity of rabbits undergoing electrostimulation of the skin and dental pulp]. / Vliianie angiotenzina II i naloksona na notsitseptivnuiu chuvstvitel'nost' krolikov pri élektrostimuliatsii kozhi i pul'py zuba.

In unanesthetized rabbits intraventricular and intravenous administration of angiotensin II resulted in a decrease of the somatosensory evoked potential amplitude in response to nociceptive electrodental stimulation but not nociceptive electrocutaneous stimulation. Saralasin administered intraventricularly abolished the effect of angiotensin II. Naloxone injected by the same route increased the evoked potential amplitude in response to electrodental but not to electrocutaneous stimulation and also reversed the analgesic effect of angiotensin II. The selectivity of the antinociceptive effect of angiotensin II is probably due to the presence of different specific peptide pain mechanisms of varying origin.

[Electrophysiologic and chemoreceptive characteristics of pontomedullary and thalamic neurons during the process of ontogenetic development]. / Elektrofiziologicheskie i khemoretseptivnye kharakteristiki pontomedulliarnykh i talamicheskikh neironov v protesse ontogeneticheskogo razvitiia.

The background and evoked activity of reticular units in the medulla, pons and ventrobasal complex of the thalamus was studied on cat's fetuses and kittens 54-65 and 1-60 days old, respectively. 63% (pons) and 92% (medulla) of spontaneously active cells were recorded in the fetuses. The highest percentage of evoked responses (60% in the fetuses) was observed upon stimulation of the tongue. Repeated application of stimuli facilitated the firing during the interstimulus intervals, especially during the early developmental stages. Sensitivity to transmitters in the fetuses was maximal to noradrenalin (87%) and glutamate (70%) and minimal to acetylcholine (43%). With development of the animal the number of adrenosensitive units decreased, that of the cholinosensitive increased, and the sensitivity to glutamate remained at the same level. A conclusion is made that the synaptic processes at early developmental stages are mainly of adrenergic and glutamate nature.