Picrotoxin blocks the anxiolytic- and panicolytic-like effects of sodium valproate in the rat elevated T-maze.
The effect of acute sodium valproate administration, an anxiolytic and putative panicolytic drug, was evaluated in rats tested in the elevated T-maze, an animal model that measures two defensive reactions: avoidance (inhibitory avoidance), related to generalized anxiety, and escape (escape from open arms), related to panic. Additionally, the involvement of gamma-aminobutyric acid (GABA) neurotransmission in sodium valproate effects was studied by picrotoxin co-administration. Sodium valproate (300 mg/kg, intraperitoneally, 30 min before the test) impaired both avoidance latency (time to leave the closed arm) and one-way escape (latency to enter the closed arm) indicating anxiolytic and panicolytic effects, respectively. Pre-treatment with picrotoxin (0.5 mg/kg, intraperitoneally, 5 min before sodium valproate administration) blocked the effects of sodium valproate on inhibitory avoidance and one-way escape. No locomotor effect was seen in the open-field. These data suggest that sodium valproate exerts anxiolytic-like and panicolytic-like effects in the elevated T-maze and that these effects were mediated by picrotoxin-sensitive GABA type A receptors.
Dombrowski
Patrícia A
PA
Laboratório de Fisiologia e Farmacologia do Sistema Nervoso Central, Departamento de Farmacologia, Setor de Ciências Biológicas, Universidade Federal do Paraná, Centro Politécnico C.P. 19031, 81540-990 Curitiba, PR, Brazil.
Fernandes
Lineane H
LH
Andreatini
Roberto
R
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001007:Anxiety / Q000188:drug therapy; D001362:Avoidance Learning / Q000187:drug effects; D004924:Escape Reaction / Q000187:drug effects; D018756:GABA Antagonists / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010200:Panic / Q000187:drug effects; D010852:Picrotoxin / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014635:Valproic Acid / Q000494:pharmacology*
D014151:Anti-Anxiety Agents; D018756:GABA Antagonists; D010852:Picrotoxin; D014635:Valproic Acid