Acetylcholine (Ach) is a neurotransmitter considered to play a critical role in processes underlying behavior, learning, and memory. Pyritinol (pyrithioxine, Encephabolâ, PRT) is a nootropic drug that increases cholinergic transmission in the central nervous system. Behavioral habituation following multiple exposures to an open field is an experimental paradigm frequently used to assess the cognitive actions of drugs. In this paradigm the decrease of exploratory activity as a function of repeated exposure to the same environment is taken as an index memory. In the present study, effects PRT administrated to aged rats in powder form added to the diet (200 mg /kg / day, p.o., for 14 days) were evaluated in the habituation to an open field. A total of 18 aged rats were randomly assigned to one of two groups control (vehicle-treated rats, n = 8) and experimental group (PRT-treated rats, n = 10) and were used in the following procedure. In the exploratory task, the post-training treatment with PRT significantly decreased the number of total area crossings and rears when compared to the control group, indicating habituation. PRT treatment enhanced retention in the total number of area crossings and rears when compared with control animals. Taken together, the data of present study suggest that muscarinic cholinergic systems could be involved in the effect of PRT in habituation of exploratory activity to an open field in aged rats.
