Time-dependent retrograde amnesic effects of muscimol on conditioned taste aversion extinction.
We explored how stimulation of GABA(A) receptors at different times during conditioned taste aversion (CTA) acquisition or extinction influenced extinction. In Experiment 1, rats acquired a CTA to 0.3% saccharin-flavored water (SAC) when it followed an injection of lithium chloride (LiCl; 81.0 mg/kg, i.p.). Following conditioning, rats received extinction training in which the GABA(A) agonist muscimol (1.0 mg/kg, i.p.), or control (saline) injections, were administered either before or after each extinction trial. Muscimol hindered extinction when administered after extinction trials. Muscimol's inhibitory effects may have impeded extinction learning by disrupting synaptic mechanisms required to consolidate information experienced during extinction training. In Experiment 2, we studied the effects of muscimol on CTA acquisition and subsequent extinction. Rats received muscimol (1.0 mg/kg, i.p.) either before or after CTA conditioning trials. Following CTA acquisition, all rats were given CTA extinction training without muscimol administration. All groups developed CTA, but the group that received muscimol before CTA conditioning trials extinguished rapidly in comparison to other treatment groups. Differences between muscimol's effects on CTA conditioning and CTA extinction indicate that fear conditioning and extinction involve, to some degree, different neuronal mechanisms.
Disorbo
Anthony
A
Department of Psychology, Neuroscience Program, Baldwin-Wallace College, 275 Eastland Rd., Berea, OH 44017-2088, USA. adisorbo@temple.edu
Wilson
Gina N
GN
Bacik
Stephanie
S
Hoxha
Zana
Z
Biada
Jaclyn M
JM
Mickley
G Andrew
GA
D000647:Amnesia / Q000139:chemically induced*; D000818:Animals; D001362:Avoidance Learning; D003214:Conditioning, Classical; D018755:GABA Agonists / Q000494:pharmacology*; D008297:Male; D009118:Muscimol / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013649:Taste
D018755:GABA Agonists; D009118:Muscimol