Influence of flupirtine,a novel nonopioid analgesic agent on somatosensory evoked potentials in rats

The effect of flupirtine, a novel nonopioid analgesic, on somatosensory evoked potentials (SEP) was investigated in anesthetized rats. Primary somatosensory potentials were evoked in the cerebral cortex by stimulation of the skin of the whiskery part of the face. Flupirtine injected i.p. dose-dependently prolonged the latency and reduced the amplitude of SEP with ID₅₀-values of 5.4 mg/kg (2.6–9.3 mg/kg) and 7.9 mg/kg (3.9–13.8 mg/kg), respectively. This effect of flupirtine (10 mg/kg, i.p.) on the latency and the amplitude of SEP, did not change when naloxone (1 mg/kg, i.p.) was given before flupirtine. The results indicate that the analgesic flupirtine decreases the primary somatosensory evoked potential by diminishing the excitability of cortical neurons. Opioid mechanisms are not involved.     

Evidence for a correlation between the latency of an early component of auditory evoked potentials and the brain levels of serotonin in albino rats.

Changes in brain serotonin levels are correlated with the latency of an early component of auditory evoked potentials (EAEP) in rats. In fact 5-hidroxytryptophan provokes an increase both in serotonin brain synthesis and in the latency of EAEP. On the other hand, PCPA provokes an opposite effect.     

Reticular potentials evoked by electrical stimulation of individual semicircular canals.

Responses of pontine reticular formation neurons following single shock electrical stimulation of single semicircular canals were recorded with tungsten microelectrodes in 40 curarized guinea-pigs. The field and unitary potentials obtained from 62 reticular sites, exhibited latency values ranging from 0.3 to 2.5 msec. The early latencies (0.3-0.5 msec) have been interpreted as responses mediated by primary vestibular fibres projecting directly to the reticular substance.     

Modification of visual,auditory, and somatosensory evoked responses in cortical primary receiving areas by nigral stimulation

Zusammenfassung Nachweis einer «unspezifischen» fördernden Wirkung von Stimulation der Substantia nigra auf «evoked potential» in den primären sensorischen Zentren des Grosshirns.

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Supported by a grant from the Japanese Ministry of Education.

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Acknowledgment. We thank Prof.N. Kato, Prof.Y. Iwase, Dr.S. Takahashi, and Dr.N. Tani for their help.     

Recovery cycles of primary evoked potentials in cat sensorimotor cortex

Résumé Quoiqu'une inhibition récurrente se présente dans le cortex sensorimoteur du chat, il n'a pas été possible d'enregistrer l'activité unitaire des neurones intercalaires de la voie récurrente. Dans les expériences décrites ici, l'onde 2 du potentiel somatique primaire évoqué par la stimulation des fibres thalamo-corticales, montrait un accroissement marqué après stimulation conditionnante; simultanément il se produisait une inhibition des ondes tardives du potentiel. Donc l'onde 2 peut être due aux neurones intercalaires inhibiteurs activés durant la phase d'inhibition.

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This study was supported by U.S.P.H.S. grant No. M-05286, and by U.S. Air Force grant No. AFOSR-62-364 to Dr.R. Hernández-Peón, in whose laboratory the study was done.     

Evidence for a correlation between the latency of an early component of auditory evoked potentials and the brain levels of serotonin in albino rats

Summary Changes in brain serotonin levels are correlated with the latency of an early component of auditory evoked potentials (EAEP) in rats. In fact 5-hidroxytryptophan provokes an increase both in serotonin brain synthesis and in the latency of EAEP. On the other hand, PCPA provokes an opposite effect.     

Effects ofγ-amino-butyric acid on the potentials evoked in vitro in the superior colliculus

Résumé L'acide butyrique gamma-amino (GABA) en basse concentration a réduit le potentiel suscité in vitro dans une tranche deColliculus superior chez le cobaye. Cette action suppressive de GABA ne s'est pas produite dans un medium sans chlore ou avec de la strychnine. On en a conclu que GABA simule le transmetteur inhibitoire dans leC. superior.     

Post-tetanic changes of bilateral dorsal root potentials evoked by stimulation of the cutaneous afferents.

In spinal cats following tetanic stimulation of the cutaneous nerve bilateral dorsal root potentials in the lumbar spinal cord are depressed. Because of differences between ipsi- and contralateral potentials, this depression can usually be evoked only on one side of the cord.     

Effect of antibrain synaptosomal fraction serum and complement on evoked potentials and impedance

Résumé L'introduction du «complément» (sérum de cobaye) dans le corps genouillé latéral du chat, produit une diminution des potentiels évoqués photiques et de l'impédance cérébrale. Ces effets sont prévenus par l'application locale d'un anti-serum réagissant spécifiquement avec les synaptosomes cérébraux.     

Influence of the visual cortex upon collicular evoked responses in the rabbit.

In rabbit, the depression of the visual cortex by KCl showed an enhancement of the collicular evoked potentials. This enhancement revealed that the visual cortex had exerted a tonic type influence upon the superior colliculus.     

Hymenin, a novel alpha-adrenoreceptor blocking agent from the Okinawan marine sponge Hymeniacidon sp

A novel bromine-containing alkaloid, hymenin, has been isolated from the Okinawan marine sponge Hymeniacidon sp. as a potent alpha-adrenoceptor blocking agent and its structure determined to be 1 on the basis of the spectral data.