Effect of conditioning stimuli upon evoked potentials in the trigeminal complex.

Stewart, Donald H.; King, Rylee

doi:10.1152/jn.1966.29.3.442

Cited by 23 publications

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“…The Nucl. tractus spinalis is reported to be involved in the corticofugal presynaptic inhibition (16)(17)(18). Therefore, some of the neurons in this nucleus may participate in the negative feed-back system.…”

Section: Discussionmentioning

confidence: 99%

Effects of Morphine on Unit Discharges Recorded From the Trigeminal Nuclei in Cats

Sasa

1969

Japanese Journal of Pharmacology

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The primary relay nuclei of the afferent sensory pathway have been demonstrated by Fujita et al. (1,2) as one of the sites of action of morphine in the central nervous system. They have shown that the evoked potentials in the spinal cord of the cat caused by afferent stimulation of the splanchnic, phrenic and inferior cardiac nerves are depressed by in travenous injection of morphine. However, Takagi et al. (3) have postulated that the inhibitory effect of morphine on the spinal cord derives from an activation of inhibitory mechanism in the midbrain reticular formation rather than from a direct action. The experiments of Mizoguchi (4) in the dog have demonstrated that morphine suppresses the evoked potentials in the Nucl. tractus spinalis n. trigemini but does not affect those in the Nucl. sensorius superior n. trigemini caused by electrical stimulation of the tooth pulp. The neurons in the former nucleus are known to receive pain and temperature impulses, while those in the latter nucleus to receive tactile impulses (5). Therefore, the experimental results presented by Mizoguchi (4) are well compatible with an explanation of the site of analgesic action of morphine.On the other hand, by using microelectrode technique Kruger and Michel (6) could not find any neuron activity uniquely sensitive to noxious stimuli in the Nucl. tractus spinalis n. trigemini, but they found that all tactile neurons in that nucleus responded well to painful stimuli.The present experiment is an attempt to elucidate the mode of action of morphine upon the unit discharges in the Nucl. sensorius superior and Nucl. tractus spinalis n. trigemini of the cat by means of microelectrode technique. METHODSSeventy male or female cats, weighing from 2.5 to 3.5 kg, were used. The details of the experimental procedures were described elsewhere (7,8). Under ether anesthesia a tracheal cannula was inserted and the head of the animal was fixed on a stereotaxic instrument of Todai-Nohken type. After removing the left frontal skull, bilateral parietal skulls and tentorium cerebelli, the animal was immobilized by transecting the spinal cord at C1 or C2 level and was sustained on an artificial respiratoin. The recording of the re sponses was started 4 hours or more after the termination of the surgical procedures and ether inhalation in a sound-proof room maintained at 27°C.

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Section: Discussionmentioning

confidence: 99%

Effects of Morphine on Unit Discharges Recorded From the Trigeminal Nuclei in Cats

Sasa

1969

Japanese Journal of Pharmacology

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“…Presynaptic inhibition is not studied yet in the trigeminal motoneurons though several papers appeared concerning the excitability changes of the trigeminal primary afferents5, 25,26).…”

Section: Discussionmentioning

confidence: 99%