Locomotion and cue-dependent behaviors are modified through corticostriatal signaling whereby short-term increases in dopamine availability can provoke persistent changes in glutamate release that contribute to neuropsychiatric disorders, including Parkinson's disease and drug dependence. We found that withdrawal of mice from repeated amphetamine treatment caused a chronic presynaptic depression (CPD) in glutamate release that was most pronounced in corticostriatal terminals with a low probability of release and lasted Ͼ50 d in treated mice. An amphetamine challenge reversed CPD via a dopamine D1-receptor-dependent paradoxical presynaptic potentiation (PPP) that increased corticostriatal activity in direct pathway medium spiny neurons. This PPP was correlated with locomotor responses after a drug challenge, suggesting that it may underlie the sensitization process. Experiments in brain slices and in vivo indicated that dopamine regulation of acetylcholine release from tonically active interneurons contributes to CPD, PPP, locomotor sensitization, and cognitive ability. Therefore, a chronic decrease in corticostriatal activity during withdrawal is regulated around a new physiological range by tonically active interneurons and returns to normal upon reexposure to amphetamine, suggesting that this paradoxical return of striatal activity to a more stable, normalized state may represent an additional source of drug motivation during abstinence. IntroductionThe neocortex refines volitional movements and goal-directed behaviors through the corticostriatal-basal ganglia-thalamocortical feedback loop (Albin et al., 1989;Jog et al., 1999). The input of this neural network consists of glutamatergic cortical afferents that excite D1-class (D1R) and D2-class dopamine receptor (D2R)-expressing striatal medium-sized spiny neurons (MSNs), which form distinct direct and indirect pathways that promote and suppress competing motor movements, respectively (Pennartz et al., 1994; Nicola et al., 2000). Modulation of these excitatory corticostriatal synapses is determined by the availability of dopamine and acetylcholine, which are necessary for the establishment of reward, attention, and motor learning (Kalivas and Volkow, 2005;Cepeda et al., 2010). Emerging evidence suggests that abnormalities in the availability of these neuromodulators may promote an imbalance between direct and indirect striatal pathways (Beutler et al., 2011;Kozorovitskiy et al., 2012; to produce the motor and neuropsychological symptoms of Parkinsonism and drug dependence Bamford and Cepeda, 2009).Addiction is considered a chronic, allostatic condition (Ahmed and Koob, 2005) characterized by drug seeking behaviors and relapse after withdrawal (Kalivas and Volkow, 2005). Psychostimulants have a high potential for abuse because they acutely increase brain dopamine levels (Sulzer, 2011) and their repeated use can trigger long-lasting changes in striatal glutamate (Pierce et al., 1996; Cornish et al., 1999; and acetylcholine (Abercrombie and DeBoer, 1997;Bamford...

During Pavlovian conditioning, pairing of a neutral conditioned stimulus (CS) with a reward leads to conditioned reward-approach responses (CRs) that are elicited by presentation of the CS. CR behaviors can be sign tracking, in which animals engage the CS, or goal tracking, in which animals go to the reward location. We investigated CR behaviors in mice with only ∼5% of normal dopamine in the striatum using a Pavlovian conditioning paradigm. These mice had severely impaired acquisition of the CR, which was ameliorated by pharmacological restoration of dopamine synthesis with L-dopa. Surprisingly, after they had learned the CR, its expression decayed only gradually in following sessions that were conducted without L-dopa treatment. To assess specific contributions of dopamine signaling in the dorsal or ventral striatum, we performed virus-mediated restoration of dopamine synthesis in completely dopamine-deficient (DD) mice. Mice with dopamine signaling only in the dorsal striatum did not acquire a CR, whereas mice with dopamine signaling only in in the ventral striatum acquired a CR. The CR in mice with dopamine signaling only in the dorsal striatum was restored by subjecting the mice to instrumental training in which they had to interact with the CS to obtain rewards. We conclude that dopamine is essential for learning and performance of CR behavior that is predominantly goal tracking. Furthermore, although dopamine signaling in the ventral striatum is sufficient to support a CR, dopamine signaling only in the dorsal striatum can also support a CR under certain circumstances.

Objective We aimed to determine if the severity of inhalation injury evokes an immune response measurable at the systemic level and to further characterize the balance of systemic pro- and anti-inflammation early after burn and inhalation injury. Summary Background Data Previously we reported that the pulmonary inflammatory response is enhanced with worse grades of inhalation injury, and that those who die from their injuries have a blunted pulmonary immune profile compared to survivors. Methods From August 2007 to June 2011, bronchoscopy was performed on 80 patients admitted to the burn intensive care unit when smoke inhalation was suspected. Of these, inhalation injury was graded into one of five categories (0, 1, 2, 3, and 4), with Grade 0 being the absence of visible injury and Grade 4 corresponding to massive injury. Plasma was collected at the time of bronchoscopy and analyzed for 28 immunomodulating proteins via multiplex bead array or ELISA. Results The concentrations of several plasma immune mediators were increased with worse inhalation injury severity, even after adjusting for age and % TBSA. These included interleukin (IL)-1RA (p=0.002), IL-6 (p=0.002), IL-8 (p=0.026), granulocyte colony stimulating factor (p=0.002), and monocyte chemotactic protein (MCP)-1 (p=0.007). Differences in plasma immune mediator concentrations in surviving and deceased patients were also identified. Briefly, plasma concentrations of IL-1RA, IL-6, IL-8, IL-15, Eotaxin, and MCP-1 were higher in deceased patients compared to survivors (p<0.05 for all), while IL-4 and IL-7 were lower (p<0.05). After adjusting for the effects of age, % TBSA, and inhalation injury grade, plasma IL-1RA remained significantly associated with mortality (OR 3.12, 95% CI 1.03–9.44). Plasma IL-1RA also correlated with % TBSA, inhalation injury grade, fluid resuscitation, Baux score, revised Baux score, Denver score, and the Sequential Organ Failure Assessment score. Conclusion The severity of smoke inhalation injury has systemically reaching effects, which argues in favor of treating inhalation injury in a graded manner. Additionally, several plasma immune mediators measured early after injury were associated with mortality. Of these, IL-1RA appeared to have the strongest correlation with injury severity and outcomes measures, which may explain the blunted pulmonary immune response we previously found in non-survivors.