Protein Synthesis and Long-Term Memory Formation in the Day-Old Chick

Abstract

Protein synthesis, and more specifically the immediate-early genes (IEG), Fos and Jun induction was studied after passive avoidance training in the day-old chick. Polyclonal antibodies directed against Fos and Jun proteins revealed two anti-Fos and two anti-Jun immunoreactive bands with apparent molecular weights of 47, 54, 39 and 54 kDa respectively. Since the 54 kDa band was common to both antibodies it maybe an activator protein -1 complex (AP-1 protein). These bands were expressed in both left and right intermediate medial hyperstriatum ventrale (IMHV) and lobus parafactorius (LPO) up to four hours after training. The MeA training experience significantly induced these bands in the left IMHV 1 hour and right LPO 2 hours after training. Injection of the NM DA receptor antagonist MK-801 prior to training attenuated learning-associated induction of these proteins at 1 hour in the left and right IMHV and 2 hours in right LPO. Fos and Jun immunocytochemistry 2 hours post-training showed that activity increased in both left and right IMHV and LPO, with the greatest rise in right LPO. Induction in all areas was abolished by the inhibitor of protein synthesis, anisomycin (ANI). Studies of the amnestic effect of ANI showed two periods of ANI sensitivity, one when injected up to 90 minutes and the second between 4-5 hours post-training. This second period of ANI sensitivity preceded the glycoprotein synthesis inhibitor sensitive phase by about 1 hour.