[Effects of intrabasolateral amygdala infusions of GABAA-receptor agonist and antagonist on expression and extinction of conditioned fear in rats with different freezing duration].

The rats were divided into two groups (little and much freezing animals) on the grounds of differences in freezing times after fear conditioning. Effects of bilateral intrabasolateral amygdale infusions of GABAA-receptors agonist (muscimol, 0.1 microg/0.5 microL in each side), antagonist (bicuculline, 0.07 microg/0.5 microL), saline (control, 0.5 microL) on expression and extinction of fear were compared in two rats groups. Muscimol infusion before retention test led to a decrease the time of freezing, it maximal biased on fear expression in little freezing rats. Bicuculline infusion increased aggressiveness of rats, decreased freezing time, induced elements of panic behavior, and evoked maximal behavioral changes in much freezing animals. Muscimol or bicuculline infusion before extinction training resulted in facilitation of extinction in much freezing rats, but not effected in little freezing animals. Received results testified to non-equivalence influences of GABA-receptors agonist and antagonist in animals with different fear levels and supposed differences in GABAergic receptors.