Resumo

Anabolic androgenic steroids (AAS) are often misused by adolescents and athletes. Their effects vary according to chemical structure and metabolism, route of administration, and AAS regimen. In several reports, this misuse has been associated with altered behavior, but little is known about the effects of AAS on cognitive functions. In this study, the effects of high doses of TP on the performance of rats in object recognition and spatial working memory (spontaneous alternation) tasks were investigated. Adult Wistar male rats (maintained isolated in plastic cages, under a 12 h light/12 h dark cycle and at a constant temperature of 25±1 °C, with food and water available ad libitum) were randomly assigned to one of the following groups: injected with sesame oil (Vehicle - VEH) or injected with 10.0 mg/kg testosterone propionate (TP). The injections were administered i.m. every 48 h for 45 days. In the novel object recognition task, rats (n = 6-7 per group) were individually placed in circular arena (diameter = 1.0m) for 5 min with two similar objects (training session) and were individually placed in same arena, after 24 h, with one novel object and one old object for 5 min (test session). In the spatial working memory task, rats were individually placed in a plus-maze, made of wood and with four enclosed arms (47 cm x 16 cm x 34 cm) extending from a central platform (16 cm x 16 cm). Rats were allowed to explore the apparatus for 10 min during which number of alternations (4 different arm choices in 4 consecutive arms entries) was recorded. After the behavioral tests, animals were sacrificed to analyze testicular weight. Regarding the behavioral assessment, rats treated with 10 mg/kg testosterone propionate (TP 10) spent less time exploring the new objects than vehicle (VEH). Indeed, significant difference in percent time of new objects exploration was found in the test session (mean + SE = 84.425 + 4.806 (VEH) and 58.696 + 4.532 (TP); t=3.869 and p=0.006). However, no effects of testosterone propionate administration were found on spontaneous alternation performances. Extending findings from previous studies, the dose, the duration and scheme of TP treatment applied in the present study induced a reduction in testicular weight in relation to average body weight (t=4.33 and p=0.001 compared to VEH-treated group). Although more studies are necessary to clarify this issue, our data suggest that AAS abuse could induce memory deficits, specifically in tasks involved with episodic contexts.