Effect Of An Anxiolytic Agent On Spatial Learning Strategy Preference In Prepubertal Male Rats
Rodents rely on spatial learning and memory to efficiently navigate a complex environment. Distinct brain areas mediate different types of spatial learning strategies. The hippocampus-dependent place strategy utilizes spatial cues in the environment to guide the rodent to a goal, while striatum-dependent response and stimulus-response strategies rely on proprioceptive cues or cues proximal to a goal, respectively, to guide the rodent to a goal. The spatial strategy employed to learn a task is influenced by a range of factors including biological sex, age, and anxiety. Previous reports have found that high levels of natural, or trait, anxiety tend to bias prepubertal male rats towards a stimulus-response learning strategy. The effect of reduced transient, or state, anxiety on spatial strategy preference in prepubertal rats is yet to be determined. In the present study, an anxiolytic agent, diazepam, was administered to prepubertal male rats to determine its effect on expression of anxiety-like behaviors on an open field test and spatial learning strategy preference on a visible platform water maze (VPWM) task. Prepubertal male rats treated with a low dose of diazepam (2.5 mg/kg) displayed reduced anxiety in comparison to prepubertal male rats treated with vehicle or a high dose of diazepam (5 mg/kg). A separate sample of prepubertal male rats treated with vehicle displayed a significant preference for a stimulus-response learning strategy as reported previously, while males treated with either a low or high dose of diazepam displayed no spatial learning strategy preference. Taken together, these results support previous findings that higher levels of anxiety bias prepubertal male rats towards a stimulus-response learning strategy, indicating that reduction of anxiety shifts strategy preference away from a stimulus-response learning strategy.