Effect of Lead Intake on Extinction of Short-Term Memory Trace (CTA) in Rats

Abstract

Abstract The effect of lead acetate on the extinction of conditioned taste aversion (CTA—short-term memory trace) was studied in albino rats. Three groups of animals of both sexes weighing between 150 and 200 g and 2 to 3 months old were selected and maintained with a staple diet under uniform husbandry conditions. The CTA was induced by 30-min saccharin (0.1%) drinking followed 30 min later by poisoning (lithium chloride 25 mg/100 g body weight). Retention trials were done 1 to 5 days later by offering the animal saccharin again; in Group 1 (n = 20) only one trial was done, whereas in Groups 2 (n = 22) and 3 (n = 22) regular trials were done in between 1 to 7 days. Only Groups 1 and 3 were exposed to lead (2500 μg/kg) a day before each extinction trial, and saccharin was injected per os by mouth if their consumption of fluid was inadequate. The extinction of CTA for saccharin in unexposed rats lasted about 2 weeks. Lead had no effect on the water consumption of CTA-trained animals. Lead retarded extinction of CTA by a month during saccharin trials.