Heterogeneous responses of substantia nigra pars reticulata neurons to gamma-hydroxybutyric acid administration.
The effect of intravenous administration of gamma-hydroxybutyric acid (GHB) (50-400 mg/kg) on the firing rate of substantia nigra pars reticulata (SN-PR) neurons was studied by making single cell extracellular recordings in unanesthetized rats. For comparison, the effect of intravenous muscimol (0.5-2 mg/kg) and ethanol (0.5-2 g/kg) was also studied. GHB produced variable effects: dose-related inhibition in 7 out of 18 (38.8%) neurons and no significant change in 11 out of 18 (61.2%) neurons tested. In contrast, muscimol and ethanol produced a dose-related inhibition of the SN-PR firing rate. The results indicate that GHB, unlike muscimol and ethanol, has no profound effect on the activity of SN-PR neurons, and thus disinhibition of dopaminergic units, through inhibition of SN-PR neurons, is probably not the mechanism by which GHB stimulates the firing rate of dopaminergic neurons.
Diana
M
M
Department of Neuroscience B.B. Brodie, University of Cagliari, Italy.
Pistis
M
M
Muntoni
A
A
Gessa
G
G
D000818:Animals; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology; D007275:Injections, Intravenous; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012978:Sodium Oxybate / Q000008:administration & dosage / Q000494:pharmacology*; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects*
D009118:Muscimol; D000431:Ethanol; D012978:Sodium Oxybate