Differential pharmacological reactivity of aversion induced by stimulation of periaqueductal gray or mesencephalic locomotor region.
Rats were trained to switch-off aversive electrical brain stimulations applied to the periaqueductal gray (PAG) or mesencephalic locomotor region (MLR) by pressing a bar (switch-off behavior). We investigated the effects of IP injections of the benzodiazepine (BZ) receptor inverse agonist FG 7142 (2.5, 5, 10 mg/kg) or BZ receptor agonist chlordiazepoxide (CDP: 5 mg/kg) on the switch-off latency, i.e., the time elapsed between the onset of the stimulation and its offset by a press of the bar. It was found that FG 7142 decreased, whereas CDP increased the mean switch-off latency for electrical stimulation of the PAG, which is interpreted as a potentiating effect of FG 7142 and a reducing effect of CDP on the electrically induced aversive state. By contrast, neither FG 7142 nor CDP were found to affect the mean switch-off latency for MLR stimulations. These results suggest a difference in the pharmacological sensitivity to BZ receptor ligands between aversive states elicited by electrical stimulation of the PAG or MLR.
Depoortere
R
R
D.N.B.C. Centre de Neurochimie du C.N.R.S., Strasbourg, France.
Di Scala
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G
Angst
M J
MJ
Sandner
G
G
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D002243:Carbolines / Q000494:pharmacology*; D002707:Chlordiazepoxide / Q000494:pharmacology*; D004558:Electric Stimulation; D008297:Male; D008636:Mesencephalon / Q000187:drug effects*; D010487:Periaqueductal Gray / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D011963:Receptors, GABA-A / Q000187:drug effects*
D002243:Carbolines; D011963:Receptors, GABA-A; C035874:FG 7142; D002707:Chlordiazepoxide