HAND. Diminished infection levels in the CNS are probably critical in reversing HIVdriven neurite damage, although our results caution that chronic exposure to opiates may inflict damage even in the absence of HIV. Since 1934, when Calvin Hall conceived the open field for the first time, the initial brief exposure of animals to the novel environment has been used to test emotionality in rodents. On the other hand, the re-exposure to the open field has been considered as a habituation to the novel environment, one of the most elementary forms of non-associative hippocampal-dependent learning. Since response to novelty is a complex mechanism that involves several processes including arousal, attention, anxiety, fear and stress-related factors, the habituation should result in the decrease of fear and stress when the animal is reexposed to the test situation. Although habituation is commonly measured by evaluating the decrease of exploratory behaviour when the environment start to be familiar, other parameters can be also used . Contrary to habituation, sensitization is a non-associative learning in which the re-exposure to the initial stimulus increases the initial behavioural response. Systemic post-training scopolamine treatment, a nonselective muscarinic receptor antagonist, disrupted mice habituation in the nose-poke test, open field task and activity cage test . In rats, the habituation to odor is impaired by post-training scopolamine treatment . On the other hand, post-training scopolamine treatment at 0.75 mg/kg, preserved rat’s memory consolidation in the open field habituation task. In above mentioned studies only locomotion and/or exploration were evaluated as habituation parameters. Having in mind that two behaviours associated with fearful and stressful situations, grooming and defecation, have not being considered in the above mentioned ZM-447439 web reports, the first aim of the present study was to evaluate the effects of scopolamines posttraining treatment on both emotional and locomotors/exploratory components of the open field 22408714 habituation task. The effect of high doses of scopolamine on 16041400 memory consolidation has been tested in fear conditioning and passive avoidance tasks. The results from these studies indicated that scopolamine post-training treatment in a dose of 50 mg/kg changed neither tone nor context fear conditioning in rats, while the dose of 30 mg/kg impaired memory consolidation of the passive avoidance task 
in mice. The effect of high doses of scopolamine on memory consolidation has not been tested in the Scopolamine Dual Effect on Habituation open field habituation task. Since the data from the literature indicate that the most frequently used doses of scopolamine efficient on memory consolidation studies are 1 and 30 mg/kg, low and high dose respectively, given immediately after the acquisition task, the second aim of the present study was to compare the effect of these doses on the open field habituation. Material and Methods Experimental Animals Experiments were carried out on male Wistar rats, weighing 200250 g. The animals were housed in standard Macrolon cages on sawdust bedding. They were kept in an air-conditioned room, at 30% humidity and under a 12 h light/12 h dark cycle. Food and tap water were available ad libitum. One week before the experimental procedure, the rats were handled daily for five minutes each. The behavioural tests were performed during the light period. All procedures related to the animal mai
