Bicuculline-induced neocortical epileptiform foci and the effects of 6-hydroxydopamine in developing rats

Brain Res Bull. 1991 May;26(5):693-8. doi: 10.1016/0361-9230(91)90162-d.

Abstract

Catecholamines (dopamine and norepinephrine) are considered to be predominantly inhibitory neurotransmitters in the brain and their depletion produced by 6-hydroxydopamine may result in proconvulsant effects. In our experiments on rats aged 5, 7, 9, 12, 15, 18, 25 and 90 days under urethane anesthesia we demonstrated the development of neocortical epileptic focus evoked by topical application of bicuculline methiodide. In experimental groups aged 7, 12, 18, 25 and 90 days a chronic depletion of catecholamines was induced using pretreatment with 6-hydroxydopamine early postnatally. An epileptogenic focus was induced in all age groups; duration of a single discharge decreased with age in both control and experimental animals. The spread of activity from the primary focus to contralateral frontal cortex via callosal connections was as rapid as in controls. However, the transfer of discharge to occipital regions was delayed and the number of discharges decreased in experimental rats. Our study demonstrated a substantial role of catecholamines for synchronization of focal discharges in neocortex and a promoting role of catecholamines in association pathways within neocortex.

MeSH terms

  • Animals
  • Bicuculline / analogs & derivatives*
  • Bicuculline / pharmacology
  • Catecholamines / physiology*
  • Cerebral Cortex / drug effects*
  • Cerebral Cortex / growth & development
  • Electroencephalography
  • Epilepsy / chemically induced
  • Epilepsy / physiopathology*
  • Frontal Lobe / drug effects
  • Frontal Lobe / growth & development
  • Male
  • Occipital Lobe / drug effects
  • Occipital Lobe / growth & development
  • Oxidopamine / pharmacology*
  • Rats
  • Rats, Inbred Strains

Substances

  • Catecholamines
  • bicuculline methiodide
  • Oxidopamine
  • Bicuculline