Inhibition of nigral and neocortical cells by gamma-hydroxybutyrate: a microiontophoretic investigation.
gamma-Hydroxybutyrate (GHB) and gamma-aminobutyrate (GABA) were applied microiontophoretically near spontaneously active cells in the substantia nigra and the neocortex of chloral hydrate-anaesthetized rats. Whereas GABA in "low doses" (i.e. 20 nA ejection currents) depressed the activity of cells in both areas, GBH reduced the firing rate only when the compound was expelled with two to three times higher ejection currents. Under these conditions GHB depressed about half of the nigral but the majority of the neocortical cells tested. The depressant action of GABA was readily antagonized by microiontophoretic bicuculline methiodide whereas the effects of GHB were resistant to this alkaloid. Intraperitoneally administered GHB in doses of 300 and 600 mg/kg reduced the firing rate of the majority of spontaneously active neocortical cells. In conclusion, GHB inhibits the firing of nigral and neocortical neurons. However its effects are not mediated through the activation of bicuculline-sensitive GABA receptors.
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D018756:GABA Antagonists; D006885:Hydroxybutyrates / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects; D051381:Rats; D013378:Substantia Nigra / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*
D018756:GABA Antagonists; D006885:Hydroxybutyrates; D001640:Bicuculline