The adenosine A 2A receptor is specifically enriched in the medium spiny neurons that make up the 'indirect' output pathway from the ventral striatum, a structure known to have a crucial, integrative role in processes such as reward, motivation, and drug-seeking behavior. In the present study we investigated the impact of adenosine A 2A receptor deletion on behavioral responses to morphine in a number of reward-related paradigms. The acute, rewarding effects of morphine were evaluated using the conditioned place preference paradigm. Operant self-administration of morphine on both fixed and progressive ratio schedules as well as cue-induced drug-seeking was assessed. In addition, the acute locomotor response to morphine as well as sensitization to morphine was evaluated. Decreased morphine selfadministration and breakpoint in A 2A knockout mice was observed. These data support a decrease in motivation to consume the drug, perhaps reflecting diminished rewarding effects of morphine in A 2A knockout mice. In support of this finding, a place preference to morphine was not observed in A 2A knockout mice but was present in wild-type mice. In contrast, robust cue-induced morphine-seeking behavior was exhibited by both A 2A knockout and wild-type mice after a period of withdrawal. The acute locomotor response to morphine in the A 2A knockout was similar to wild-type mice, yet A 2A knockout mice did not display tolerance to chronic morphine under the present paradigm. Both genotypes display locomotor sensitization to morphine, implying a lack of a role for the A 2A receptor in the drug-induced plasticity necessary for the development or expression of sensitization. Collectively, these data suggest a differential role for adenosine A 2A receptors in opiate reinforcement compared to opiate-seeking.

Adenosine and glutamate have been implicated as mediators involved in the self-administration of alcohol. In the present study we sought to determine whether adenosine receptors could interact with metabotropic glutamate receptors to regulate operant responding for alcohol and also the integration of the salience of alcohol-paired cues. Alcohol-preferring (iP) rats were trained to self-administer alcohol under operant conditions. The availability of alcohol was paired with an olfactory cue plus a stimulus light. Rats were examined under fixed ratio responding and also following extinction under a cue-induced reinstatement paradigm. Administration of the selective adenosine A2A receptor antagonist, SCH 58261, reduced fixed ratio responding for alcohol in iP rats in a dose-related manner. Furthermore, the combination of a subthreshold dose of SCH 58261 with a subthreshold dose of the mGlu5 receptor antagonist MTEP also reduced alcohol self-administration and increased the latency to the first reinforced response, suggesting a pre-ingestive effect. Moreover, this combination of SCH 58261 and MTEP also prevented the conditioned reinstatement of alcohol-seeking elicited by the re-presentation of cues previously paired with alcohol availability. In contrast, combinations of the selective adenosine A1 receptor antagonist, DPCPX, with either SCH 58261 or MTEP had no effect on alcohol responding. Collectively, these data suggest a functional interaction between adenosine A2A and mGlu5 receptors in relation to alcohol-seeking and the integration of the drug-related cues.

To scaffold the development of problem-solving skills in chemistry, chemistry educators are exploring a variety of instructional techniques. In this study, we have designed, implemented, and evaluated a problem-solving workflow – “Goldilocks Help”. This workflow builds on work done in the field of problem solving in chemistry and provides specific scaffolding for students who experience procedural difficulties during problem solving, such as dead ends (not being able to troubleshoot) and false starts (not knowing how to initiate the problem-solving process). The Goldilocks Help workflow has been designed to scaffold a systematic problem-solving process with a designation of explicit phases of problem solving, to introduce students to the types of questions/prompts that should guide them through the process, to encourage explicit reasoning necessary for successful conceptual problem solving, and to promote the development of metacognitive self-regulation skills. The tool has been implemented and evaluated over a two-year period and modified based on student and instructor feedback. The evaluation demonstrated a shift in students’ beliefs in their capacities to use the strategies required to achieve successful problem solving and showed their capacity to employ such strategies.

These studies systematically assessed the impact of AD on BBB drug transport in a relevant animal model, and have demonstrated a reduction in the brain uptake of passively-absorbed molecules in this mouse model of AD.