The increased uptake of DA observed in the NAc core and shell of SI rats in the current study and in the NAc core in a previous report (Yorgason em et al /em , 2013) suggests that SI leads to augmented DAT levels in this brain region (Yorgason em et al /em , 2015). nor-binaltorphimine (nor-BNI) increased DA levels selectively in SI subjects. Acute ethanol elevated DA in SI and GH rats and nor-BNI pretreatment augmented this effect in SI subjects, while having no effect on ethanol-stimulated DA release in GH rats. Together, these data suggest that KORs may have increased responsiveness following SI, which could lead to hypodopaminergia and contribute to an increased drive to consume ethanol. Indeed, SI rats exhibited greater ethanol intake and preference and KOR blockade selectively attenuated ethanol intake in SI rats. Collectively, the findings that nor-BNI reversed SI-mediated hypodopaminergic state and escalated ethanol intake suggest that KOR antagonists may represent a promising therapeutic strategy for the treatment of alcohol use disorders, particularly in cases linked to chronic early-life stress. Introduction Chronic early-life stress, such as childhood neglect, often results in stress and affective disorders and increased probability of drug and alcohol abuse in adulthood (Anda voltammetry and microdialysis in freely moving animals were used to ANX-510 examine changes in NAc KOR-mediated DA signaling following chronic adolescent stress and to investigate the effects of KOR blockade on baseline and ethanol-induced changes in NAc DA levels in SI and GH animals. KORs were observed to be functionally hyperactive in SI rats, and DA levels at baseline were lower in SI compared with GH rats. We also used an intermittent ethanol drinking paradigm to show that SI animals had significantly greater intake and preference compared with GH animals, effects that were selectively reduced following KOR blockade. Materials and methods Group and Isolation Housing Male Long-Evans rats were purchased from Harlan at PD 21. At PD 28, following a week of acclimation in standard housing conditions (four animals per cage, food and water voltammetry, microdialysis, and ethanol drinking experiments. An experimental time line is shown in Physique 1a (voltammetry and microdialysis) and Physique 1b (ethanol drinking). A total of four cohorts were used in the ANX-510 current study; one each for voltammetry and drinking and two for microdialysis experiments. Open in a separate window Physique 1 (a) A schematic of the experimental paradigm. Male, LongCEvans rats arrived at the facility on postnatal day (PD 21) and were maintained in group housing to acclimate for 1 week. On PD 28, half the rats were housed individually while the other half remained in group housing. ELISA, voltammetry, and microdialysis experiments were conducted between PD 84 and PD 110. (b) After the housing paradigm was completed, all rats were single housed on PD 84. Ethanol drinking experiments began Nkx1-2 on PD 87 and continued for 7 weeks. (c) Coronal sections showing microdialysis probe locations. Microdialysis probes were inserted in the NAc using the rat atlas by Paxinos and Watson (2007). Fast Scan Cyclic Voltammetry (FSCV) FSCV was used to characterize the functionality of KORs in the NAc of SI (core, AgCl) at the rate of 400?V/s. Extracellular concentrations of DA were assessed by comparing the current at the peak oxidation potential for DA with ANX-510 electrode calibrations of known concentrations of DA (3?M). Once the extracellular DA response was stable for three consecutive stimulations, a cumulative concentration response curve of the KOR agonist, U50,488 (10, 30, 100, 300, 1000?nM), was run by bath applying the drug to NAc slices. All FSCV data were analyzed using the Demon Voltammetry and Analysis software (Yorgason analysis. A two-tailed Student’s voltammetry. The color plot generated by a single 4-ms electrical stimulation in the NAc core slice and its matched concentration time traces showing DA release are shown in Physique 2a and b respectively. Electrically stimulated ANX-510 DA release (Physique 2c; GH=550.835.8; SI=981.778.6; axis: time, axis: voltage, axis: current) along with corresponding DA traces illustrating electrically stimulated DA release (peak) in GH (red) and SI (blue) rats (b) in the.