Despite very extensive studies related to molecular processes underlying memory formation, still little known about the potential differences in the brain biochemistry between "good" and "poor" learners belonging to a random population of young animals. In the present study, an attempt was taken to correlate the individual variation in short- and long-term spatial memory in three different lines of young, healthy rats: inbred Wistar (W), outcrossed Wistar/Spraque Dawley (W/S) and pigmented Long-Evans rats, with hippocampal levels of selected enzymes known as "memory molecules" including neuronal (n), endothelial (e) and inducible (i) NOS, CaMKII , PKA and ChAT.