Increased Fear Learning Coincides with Neuronal Dysinhibition and Facilitated LTP in the Basolateral Amygdala following Benzodiazepine withdrawal in Rats.

NORA A. ISOARDI, IRENE D. MARTIJENA, HUGO F. CARRER AND VICTOR A. MOLINA

Nature publishing Group

Año: 2004 vol. 29 p. 1852 - 1852

nimals chronically administered with diazepam (DZM -- 2 mg/kg/day i.p.) or vehicle (VEH) for 21 days were tested in a fear-conditioning paradigm 4 days after the last administration. Increased freezing was observed in DZM withdrawn rats as compared to VEH injected control rats in both associative and nonassociative context and this increase was greatest for the DZM withdrawal group in the paired context. In animals anesthetized with urethane, single pulses in the medial prefrontal cortex evoked a field potential including a population spike (PS) in the basolateral complex of the amygdala (BLA) of control animals, whereas in DZM withdrawn animals multiple PSs were evoked. In brain slices from control rats, stimulation of the external capsule evoked a field potential including a PS in the BLA, whereas in DZM withdrawn rats multiple PSs were evoked. The amplitude of the PS was smaller in slices obtained from DZM withdrawn rats than from control rats, and paired pulse inhibition was signi