Potential learning and memory disruptors and enhancers in a simple, 1-day operant task in mice

The objective of this study was to develop a rapid, 1-day learning and memory assay in mice that is sensitive to the effects of compounds that could impair or enhance acquisition and retrieval. Swiss-Webster, male mice were placed in experimental chambers for a 1-h acquisition session with an intermittent, audible tone. If a nose-poke response occurred during the tone, an Ensure water solution was presented. After 1 h, the mice returned to the chambers for 2 h. Drugs were injected before or after sessions to determine the effects on acquisition and/or retrieval. Mice injected with saline learned a nose-poke response as measured by decreased latencies to earn 10 reinforcers, increased reinforced response rates, and decreased nonreinforced response rates. Scopolamine and acetazolamide impaired retrieval of the nose-poke response, whereas ketamine only modestly impaired retrieval. Doses of 8-OH-DPAT or the novel carbonic anhydrase activator, MAI27, either had no effect or impaired some measures of responding. Neither 8-OH-DPAT nor MAI27 were able to prevent the modest impairments produced by ketamine. The simple, 1-day operant task is a rapid assay that can be used as an initial screen to test the effects of learning and memory disruptors and potentially enhancers.