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Addiction is characterized as a chronic debilitating disease. One devastating feature of addiction is the susceptibility of relapse (40-60%) after stretches of abstinence. One theory that may account for relapse suggests that drug cues (e.g., paraphernalia) may increase stress hormones, and this may prompt relapse. Repeatedly pairing a neutral cue with a reward is commonly utilized to measure what subjects learn about a cue that is predictive of reward. Research has shown that animals that attend to a cue more than to the reward (sign trackers) may be more vulnerable to drug addiction. Additionally, research has shown that sign tracking is associated with an increase in corticosterone, a primary stress hormone. PT150 is a novel glucocorticoid receptor antagonist that moderates the release of corticosterone. In the current experiment, it was hypothesized that subjects given repeated administration of PT150 would reduce sign tracking compared to subjects given placebo. Time spent (in seconds) near a cue that predicts reward (conditional stimulus) served as a measure of sign tracking, and PT150 or placebo was administered following sign tracking. An independent-samples t test revealed that subjects that received PT150 had reduced time spent near the conditioned stimulus compared to controls. Given the devastating effects of drug addiction, identification of a potential pharmacological intervention in the reduction of relapse would be of great value. Therefore, future research is needed to validate the use of PT150 in reducing behaviors associated with drug addiction. (PsycINFO Database Record

The main findings from the current study are that the glucocorticoid receptor antagonist PT150 dose dependently reduces sign tracking. Because persistent sign tracking behavior is associated with drug relapse, the ability to reduce it may contribute to drug addiction treatment. Potential pharmacological treatments that alter the glucocorticoid stress system may be of significance for drug addiction research.

State dependent learning effects have been widely studied in a variety of drugs of abuse. However, they have yet to be studied in relation to sexual motivation. The current study investigated state-dependent learning effects of cocaine in male Japanese quail (Coturnix japonica) using a sexual conditioning paradigm. Cocaine-induced state-dependent learning effects were investigated using a 2 × 2 factorial design with training state as one factor and test state as the other factor. During a 14-day training phase, male quail were injected once daily with 10 mg/kg cocaine or saline and then placed in a test chamber after 15 min. In the test chamber, sexual conditioning trials consisted of presentation of a light conditioned stimulus (CS) followed by sexual reinforcement. During the state dependent test, half of the birds received a shift in drug state from training to testing (Coc → Sal or Sal → Coc) while the other half remained in the same drug state (Coc → Coc or Sal → Sal). Results showed that male quail that were trained and tested in the same state (Coc → Coc or Sal → Sal) showed greater sexual conditioning than male quail that were trained and tested in different states (Sal → Coc) except when cocaine was administered chronically prior to the test (Coc → Sal). For the latter condition, sexual conditioning persisted from cocaine training to the saline test. The findings suggest that state dependent effects may alter sexual motivation and that repeated exposure to cocaine during sexual activity may increase sexual motivation which may, in turn, may lead to high risk sexual activities. An alternative explanation for the findings is also discussed.

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Background Cocaine is the number one abused psychostimulant drug that reaches addiction criterion in the US. In animals, repeated administration of cocaine results in behavioral sensitization which is thought to represent adaptations in the mesolimbic dopamine neural circuitry, the reward pathway. Cocaine-induced behavioral sensitization is evident in rodents and quail when cocaine is administered intraperitoneally (IP). Objectives The purpose of the current study was to investigate dose-dependent and temporal effects of acute and chronic intramuscular (IM) administration of cocaine in male quail. Methods After habituation to the test chambers, male quail received an IM injection of saline, 3 or 10 mg/kg cocaine and were immediately placed in the chambers. Distance traveled (in meters) was recorded in 5 min time bins for 30 min. Testing was conducted once per day for ten days with each subject receiving the same treatment throughout the experiment. Other behaviors including pecking, preening, and feather fluffing were measured. Results Cocaine-induced behavioral sensitization and tolerance were evident at relatively low doses of IM cocaine. Dose-dependent effects were evident. IM cocaine also reduced feather fluffing, a behavior that typically occurs during hypothermia. Conclusions The findings replicated and extended previous research with pigeons and suggested that IM administration of cocaine may be a relatively potent route of administration. Potency of drugs of abuse may be related to the bioavailability of a drug and its addictive properties. Thus, studying drugs of abuse using an IM route of administration may be useful in drug addiction research.

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Readers should note the use of the term animal throughout this chapter. As Hodos and Campbell (1990) pointed out, evolution is not linear with humans as the most perfectly evolved. Rather, evolution is branching, with Homo sapiens being only one of the more recently evolved limbs. Referring to laboratory animals as infrahuman or tacitly removing humans from the category of animals (as in the phrase humans and animals) has struck many behavioral scientists as inappropriate (Dess & Chapman, 1998;Poling, 1984). Therefore, to recognize this logic we use the term nonhuman animals.