Chronic benzodiazepine treatment and cortical responses to adenosine and GABA.
The effects of chronic treatment of mice with clonazepam have been examined on the responses of neocortical slices to adenosine, 5-hydroxytryptamine (5-HT) and gamma-aminobutyric acid (GABA). Responses to these agonists were measured as changes in the depolarisation induced by N-methyl-D-aspartate (NMDA). Added to the superfusion medium diazepam blocked responses to adenosine but not 5-HT; this effect was not observed with 2-chloroadenosine or in the presence of 2-hydroxynitrobenzylthioguanosine. GABA was inactive in control slices but chronic treatment with clonazepam induced responses to GABA and enhanced responses to adenosine but not 5-HT. It is suggested that the induction of GABA responses may reflect the up-regulation of GABA receptors, but the increase of adenosine responses by clonazepam implies that there is no simple relationship between adenosine receptor binding and functional responses.
Mally
J
J
Department of Pharmacology, University of Glasgow, U.K.
Connick
J H
JH
Stone
T W
TW
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects*; D002998:Clonazepam / Q000494:pharmacology; D003975:Diazepam / Q000494:pharmacology; D004566:Electrodes; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D016202:N-Methylaspartate / Q000494:pharmacology; D012701:Serotonin; D013806:Theophylline / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D014151:Anti-Anxiety Agents; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D002998:Clonazepam; D016202:N-Methylaspartate; D013806:Theophylline; D000241:Adenosine; D003975:Diazepam