Reflex effects and postsynaptic membrane potential changes during epileptiform activity induced by penicillin in decapitate spinal cords.

Published

Journal Article

The administration of a convulsant dose of penicillin enhanced the transmission of monosynaptic reflexes in spinal cords in which reflex transmission was feeble before the drug treatment, but it had little effect in cords where monosynaptic reflexes were powerful to begin with. Post-tetanic potentiation was not altered by penicillin. Polysynaptic reflexes were invariably enhanced by convulsant amounts of penicillin. Postsynaptic ("direct") inhibition was not affected in the seizure-free intervals in spinal cords treated with penicillin, but it seemed to be suppressed during tonic seizures. The disability of reflex inhibition during ictal discharges may be due to presynaptic depolarization of inhibitory terminals. Recurrent inhibition was partially suppressed in spinal cords treated with penicillin. Neurons in the dorsal and intermediate gray matter were sometimes excited, sometimes inhibited, and sometimes unaffected by seizure activity of their segment. Motoneurons in the ventral horns invariably participated in the interictal and ictal activity. The timing of clonic seizure sequences coincided with bursts of Renshaw cell discharges. Action potential of abnormal amplitude and configuration were frequently observed in convulsing motoneurons. Paroxysmal depolarizing shifts (PDSs) of motoneurons were similar to those observed by other investigators in neurons in experimental epileptic foci of the cerebral cortex, except that spinal PDSs were not followed by hyperpolarizing waves.

Full Text

Duke Authors

Cited Authors

  • Lothman, EW; Somjen, GG

Published Date

  • October 1, 1976

Published In

Volume / Issue

  • 41 / 4

Start / End Page

  • 337 - 347

PubMed ID

  • 60220

Pubmed Central ID

  • 60220

International Standard Serial Number (ISSN)

  • 0013-4694

Digital Object Identifier (DOI)

  • 10.1016/0013-4694(76)90096-1

Language

  • eng