The effect of anesthesia on acquisition and extinction of conditioned taste aversion

Abstract

Conditioned taste aversion (CTA) was established in adult rats by association of a 15-min access to 0.1% saccharin (CS) with subsequent poisoning (US 0.15 M LiCl, 4% body weight). Allobarbital anesthesia (40 mg/kg) maintained during the 5-hr CS—US interval did not prevent CTA acquisition which, however, was impaired by cortical spreading depression maintained in the same interval. Anesthesia alone evoked a weak CTA. Intraperitoneal injection of the CS (2% saccharin, 1% body weight), followed 30 min later by the US, elicited CTA in the intact rats but not in the rats anesthetized with Nembutal (40 mg/kg). On the other hand, intraperitoneal application of the CS to CTA-trained rats caused similar CTA extinction, both in anesthetized and unanesthetized animals. Intraperitoneal administration of the CS to rats anesthetized with urethane (0.9 mg/kg) elicited EEG arousal, lasting 1 to 2 min in CTA trained rats, but had no effect in naive animals. It is concluded that anesthesia blocks the initial formation of the shortterm gustatory trace, but does not prevent its association with poisoning or extinction of the already established CTA.