Neuroimaging of the effects of drug exposure or self-administration in rodents: A systematic review.

A systematic review of functional neuroimaging studies on drug (self-) administration in rodents is lacking. Here, we summarized effects of acute or chronic drug administration of various classes of drugs on brain function and determined consistency with human literature. We performed a systematic literature search and identified 125 studies on in vivo rodent resting-state functional magnetic resonance imaging (n = 84) or positron emission tomography (n = 41) spanning depressants (n = 27), opioids (n = 23), stimulants (n = 72), and cannabis (n = 3). Results primarily showed alterations in the striatum, consistent with the human literature. The anterior cingulate cortex and (nonspecific) prefrontal cortex were also frequently implicated. Upregulation was most often found after shorter administration and downregulation after long chronic administration, particularly in the striatum. Importantly, results were consistent across study design, administration models, imaging method, and animal states. Results provide evidence of altered resting-state brain function in rodents upon drug administration, implicating the brain's reward network analogous to human studies. However, alterations were more dynamic than previously known, with dynamic adaptation depending on the length of drug administration.

Kv7 channel opener retigabine reduces self-administration of cocaine but not sucrose in rats.

The increasing rates of drug misuse highlight the urgency of identifying improved therapeutics for treatment. Most drug-seeking behaviours that can be modelled in rodents utilize the repeated intravenous self-administration (SA) of drugs. Recent studies examining the mesolimbic pathway suggest that Kv7/KCNQ channels may contribute to the transition from recreational to chronic drug use. However, to date, all such studies used noncontingent, experimenter-delivered drug model systems, and the extent to which this effect generalizes to rats trained to self-administer drugs is not known. Here, we tested the ability of retigabine (ezogabine), a Kv7 channel opener, to regulate instrumental behaviour in male Sprague Dawley rats. We first validated the ability of retigabine to target experimenter-delivered cocaine in a conditioned place preference (CPP) assay and found that retigabine reduced the acquisition of place preference. Next, we trained rats for cocaine-SA under a fixed-ratio or progressive-ratio reinforcement schedule and found that retigabine pretreatment attenuated the SA of low to moderate doses of cocaine. This was not observed in parallel experiments, with rats self-administering sucrose, a natural reward. Compared with sucrose-SA, cocaine-SA was associated with reductions in the expression of the Kv7.5 subunit in the nucleus accumbens, without alterations in Kv7.2 and Kv7.3. Therefore, these studies reveal a reward-specific reduction in SA behaviour and support the notion that Kv7 is a potential therapeutic target for human psychiatric diseases with dysfunctional reward circuitry.

Decreased Serum Cocaine- and Amphetamine-Regulated Transcript Level in Internet Gaming Disorder.

OBJECTIVE: Vulnerability to internet gaming disorder (IGD) has increased as internet gaming continues to grow. Cocaine- and amphetamine-regulated transcript (CART) is a hormone that plays a role in reward, anxiety, and stress. The purpose of this study was to identify the role of CART in the pathophysiology of IGD. METHODS: The serum CART levels were measured by enzyme-linked immunosorbent assay, and the associations of the serum CART level with psychological variables were analyzed in patients with IGD (n=31) and healthy controls (HC) (n=42). RESULTS: The serum CART level was significantly lower in the IGD than HC group. The IGD group scored significantly higher than the HC group on the psychological domains of depression, anxiety, the reward response in the Behavioral Activation System and Behavioral Inhibition System. There were no significant correlations between serum CART level and other psychological variables in the IGD group. CONCLUSION: Our results indicate that a decrease in the expression of the serum CART level is associated with the vulnerability of developing IGD. This study supports the possibility that CART is a biomarker in the pathophysiology of IGD.

Brugada Phenotype Following a Cocaine Overdose.

Brugada syndrome is a rare cardiac condition characterized by distinctive electrocardiogram patterns, predisposing individuals to fatal arrhythmias. While primarily linked to a loss-of-function mutation in the SCN5A gene, acquired forms of the syndrome have been associated with various factors, including drug use. We present a case of a 31-year-old female who presented to the emergency department unresponsive following cocaine use and developed type 1 Brugada ECG patterns alongside an incomplete right bundle branch block in V1-V3, ST elevations with biphasic waves, and diffuse repolarization abnormalities with J point deviations while in the intensive care unit. This study aimed to discuss the complexity of managing drug-induced Brugada-like findings and highlights the need for further research into the mechanisms underlying cocaine-induced cardiac effects. We aimed to discuss potential mechanisms for the impact of cocaine as its role as a sodium channel blocker and its potential effects on connexin 43 in the context of Brugada syndrome. This study also reinforced the importance of differentiating between true Brugada syndrome and other similar ECG changes for appropriate care management.

Anesthetic recovery outcomes after 2 methods of nasal mucosal preparation for endoscopic sinus surgery.

PURPOSE: Our institution uses two approaches for nasal mucosal preparation during endoscopic sinus surgery (ESS) to improve surgical field visualization: topical epinephrine (TE) versus topical cocaine with injection of lidocaine containing epinephrine (TCLE). We aimed to compare anesthetic outcomes after ESS using these techniques. METHODS AND MATERIALS: We retrospectively identified adult patients at our institution who underwent ESS from May 2018 through January 2023 under general anesthesia with propofol and remifentanil infusions. Postoperative anesthetic outcomes, including pain and recovery time, were compared between patients who had mucosal preparation with TE versus TCLE using inverse probability of treatment weighting (IPTW) to adjust for potential confounders. RESULTS: Among 1449 patients who underwent ESS, 585 had TE, and 864 had TCLE. Compared with TE, during anesthetic recovery, the TCLE group had fewer episodes of severe pain (numeric pain score ≥ 7) (IPTW-adjusted odds ratio, 0.65; 95 % CI, 0.49-0.85; P = .002), less opioid analgesic administration (IPTW-adjusted odds ratio, 0.55; 95 % CI, 0.44-0.69; P < .001), and shorter recovery room stay (IPTW-adjusted ratio of the geometric mean, 0.90; 95 % CI, 0.85-0.96; P = .002). Postoperative nausea and vomiting and postoperative sedation were similar between groups. CONCLUSIONS: Patients who received preparation of the nasal mucosa with TCLE, compared with TE, were less likely to report severe pain or receive an opioid analgesic in the postanesthesia recovery room and had faster anesthetic recovery. This observation from our large clinical practice indicates that use topical and local anesthetic during endoscopic sinus surgery may have benefit for ambulatory ESS patients.

A quantitative LC-MS/MS method for investigation of polysubstance use involving heroin and cocaine.

Concurrent use of heroin and cocaine (known as the "speedball") prevails among substance use disorder populations, especially in opioid-dependent individuals, with severe consequences and a high fatality rate. Little is known about the patterns and correlations of the concurrent use of heroin and cocaine. It is vital to investigate such a polydrug use in both humans and animals to uncover concomitant toxicity and the cause of fatal overdose (death). In this study, we aimed to shed some light on the role of cocaine in the etiology of heroin-related deaths in the context of molecular pharmacokinetics (PK). For the purpose, a high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of heroin, cocaine, and their metabolites in whole blood was developed and fully validated in accordance with the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines. Then, this method was used to analyze heroin, cocaine, and their metabolites in blood from the rats intraperitoneally administered non-lethal 10 mg/kg heroin or 20 mg/kg cocaine alone, or their combination that is lethal with a proximal mortality of 33 %. The obtained results from the rats that experienced the lethal toxicity revealed that the concurrent use of heroin and cocaine significantly increased the risk of fatality from overdose. Heroin significantly slowed down the elimination of cocaine and its main metabolites in blood, while cocaine significantly enhanced heroin metabolism from 6-monoacetylmorphine (6-MAM) to morphine. Similar elimination half-lives for other heroin metabolites were observed. These findings are reported for the first time in this study, facilitating our understanding of the polysubstance metabolism and severe consequences produced by the polydrug use.

Effects of access condition on substance use disorder-like phenotypes in male and female rats self-administering MDPV or cocaine.

Substance use disorder (SUD) is a heterogeneous disorder, where severity, symptoms, and patterns of use vary across individuals. Yet, when rats self-administer cocaine under short-access conditions, their behavior tends to be well-regulated, though individual differences can emerge with long- or intermittent-access. In contrast, significant individual differences emerge when rats self-administer 3,4-methylenedioxypyrovalerone (MDPV), even under short-access conditions, wherein ~30 % of rats exhibit high levels of drug-taking. This study assessed SUD-like phenotypes of male and female rats self-administering MDPV or cocaine by comparing level of drug intake, responding during periods of signaled drug unavailability, and sensitivity to footshock punishment to determine whether: (1) under short-access conditions, rats that self-administer MDPV will exhibit a more robust SUD-like phenotype than rats that self-administer cocaine; (2) female rats will have a more severe phenotype than male rats; and (3) compared to short-access, long- and intermittent-access to MDPV or cocaine self-administration will result in a more robust SUD-like phenotype. Compared to cocaine, rats that self-administered MDPV exhibited a more severe phenotype, even under short-access conditions. Long- and intermittent-access to cocaine and MDPV temporarily altered drug-taking patterns but did not systematically change SUD-like phenotypes. Behavioral and quantitative autoradiography studies suggest phenotypic differences are not due to expression of dopamine transporter, dopamine D2 or D3 receptors, or 5-HT1B, 5-HT2A, or 5-HT2C receptors. This study suggests individuals who use synthetic cathinones may be at greater risk for developing a SUD, and short-access MDPV self-administration may provide a useful method to study the transition to disordered substance use in humans.

Molecular and circuit determinants in the globus pallidus mediating control of cocaine-induced behavioral plasticity.

The globus pallidus externus (GPe) is a central component of the basal ganglia circuit that acts as a gatekeeper of cocaine-induced behavioral plasticity. However, the molecular and circuit mechanisms underlying this function are unknown. Here, we show that GPe parvalbumin-positive (GPePV) cells mediate cocaine responses by selectively modulating ventral tegmental area dopamine (VTADA) cells projecting to the dorsomedial striatum (DMS). Interestingly, GPePV cell activity in cocaine-naive mice is correlated with behavioral responses following cocaine, effectively predicting cocaine sensitivity. Expression of the voltage-gated potassium channels KCNQ3 and KCNQ5 that control intrinsic cellular excitability following cocaine was downregulated, contributing to the elevation in GPePV cell excitability. Acutely activating channels containing KCNQ3 and/or KCNQ5 using the small molecule carnosic acid, a key psychoactive component of Salvia rosmarinus (rosemary) extract, reduced GPePV cell excitability and impaired cocaine reward, sensitization, and volitional cocaine intake, indicating its therapeutic potential to counteract psychostimulant use disorder.

A pilot study on post-mortem determination of drug abuse on dental tissues.

BACKGROUND: Post-mortem toxicology constantly deals with the research of reliable alternative matrices to be applied in case of highly damaged corpses (such us carbonized, skeletonized, human remains, etc.). Teeth represent a promising alternative matrix since dental tissues are endowed by different features, resistance and stability after death. SCOPE: Since scant literature reported on the pharmacokinetics and mechanism of incorporation of xenobiotics into dental tissues, this pilot research aims to investigate whether in the pulp can be detected the same substances found in blood in drug related death cases. Secondly, the study is addressed to disclose the possible deposit of drugs in dental hard tissues (dentine and/or enamel), thus contributing to reconstruct the drug abuse history (timing, e.g.). MATERIALS AND METHODS: The study experimented with a novel method to separately analyse dental enamel, dentin, and pulp, applied to 10 teeth collected during autopsies of drug-related deaths along with blood and hair samples for classic toxicological analyses. Each tooth was prepared by "pulverization technique" and then analysed by gas chromatography paired with mass spectrometry (GC-MS) and ultra high performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC/HR-MS) for searching cocaine, opiates, and metabolites. The results were then compared with those obtained from blood and hair samples. RESULTS: Preliminary results demonstrated that teeth differ from any other classic matrix (blood and hairs) since the qualitative correspondence of the detected substances between pulp and blood as well as dental hard tissues and hair suggests that they can be useful in post-mortem evaluation as a unique matrix for both acute and chronic assumptions of drugs. The mechanism of accumulation of substances in mineralized dental tissues emerged the most significant result, being influenced by the type of molecule and the method of assumption. The main limitation of this study is the limited availability of the sample and the absence of anamnestic information of the time, rates and method of drug assumption during life. Further research is necessary to systematically investigate the distribution of different substances within the different tissues of the tooth.

Measurement invariance of the perceived stress scale across race, sex, and time, and differential impacts on cocaine use treatment outcomes.

INTRODUCTION: To understand the influence of phenotypic characteristics, such as stress, on substance use treatment outcomes, measures must function equivalently across groups to allow for interpretable comparisons of effects. The present study evaluated measurement invariance of the Perceived Stress Scale (PSS) across race, sex, and time, examined its association with cocaine use disorder (CUD) treatment outcomes, and tested whether associations were moderated by race and/or sex. METHODS: Data from four clinical trials evaluating behavioral and/or pharmacological treatments for cocaine use were combined providing a total sample of 302 participants with DSM-IV cocaine abuse/dependence (57.6 % Black, 42.4 % White, 43.7 % females, Mage = 40.22 years, SD = 9.26). RESULTS: Factor analyses support a two-factor model (i.e., general stress, self-efficacy to cope with stressors) that demonstrated configural, metric, and scalar invariance across race and sex and configural and metric invariance across time. End-of-treatment stress and coping were both related to treatment outcomes, but not treatment retention. Interactions between baseline and end-of-treatment stress and coping self-efficacy with race and sex predicting treatment retention and outcomes were not significant. CONCLUSIONS: Results support the utility of the PSS to examine between-group differences among individuals with CUD and suggest that sociodemographic groups differ in the extent to which stress and self-efficacy to cope influence treatment outcomes.

Cocaine-derived hippuric acid activates mtDNA-STING signaling in alcoholic liver disease: Implications for alcohol and cocaine co-abuse.

The simultaneous abuse of alcohol-cocaine is known to cause stronger and more unpredictable cellular damage in the liver, heart, and brain. However, the mechanistic crosstalk between cocaine and alcohol in liver injury remains unclear. The findings revealed cocaine-induced liver injury and inflammation in both marmosets and mice. Of note, co-administration of cocaine and ethanol in mice causes more severe liver damage than individual treatment. The metabolomic analysis confirmed that hippuric acid (HA) is the most abundant metabolite in marmoset serum after cocaine consumption and that is formed in primary marmoset hepatocytes. HA, a metabolite of cocaine, increases mitochondrial DNA leakage and subsequently increases the production of proinflammatory factors via STING signaling in Kupffer cells (KCs). In addition, conditioned media of cocaine-treated KC induced hepatocellular necrosis via alcohol-induced TNFR1. Finally, disruption of STING signaling in vivo ameliorated co-administration of alcohol- and cocaine-induced liver damage and inflammation. These findings postulate intervention of HA-STING-TNFR1 axis as a novel strategy for treatment of alcohol- and cocaine-induced excessive liver damage.

Contamination of a drug consumption room with drugs and potential risks for social health care workers.

BACKGROUND: Studies have shown that contamination of surfaces by illicit drugs frequently occurs in forensic laboratories when manipulating seized samples as well as in pharmacies and hospitals when preparing medicinal drugs. In this project, we extended these studies to a Drug Consumption Room to investigate drug levels and possible exposure of the staff members. METHODS: We investigated pre and post cleaning contamination by heroin and cocaine and their degradation products 6-monoacetylmorphine and benzoylecgonine on different surfaces (tables, counters, computers and door handles) and in the ambient air. We also collected urine and hair samples from staff members to check for potential short and long term contaminations. RESULTS: Medium to heavy contamination has been detected on most surfaces and door handles; as expected, air contamination was particularly high in the smoking room. Drug levels were < LOD to very low in the urine and the hair samples of staff members tested. CONCLUSION: The cleaning efficiency of the surfaces, carried out by staff and drug users after drug consumption, was often not satisfactory. The very low drug levels in hair indicate that acute health risks for staff members are low.

Follicular Atresia in Buffalo: Cocaine- and Amphetamine-Regulated Transcript (CART) and the Underlying Mechanisms.

Atresia is a process in ovarian follicles that is regulated by hormone-induced apoptosis. During atresia, granulosa cell (GC) apoptosis is a key mechanism orchestrated through diverse signaling pathways. Cocaine- and amphetamine-regulated transcript (CART) signaling within ovarian GCs has been demonstrated to play a key role in the regulation of follicular atresia in cattle, pigs, and sheep. The present work aimed to investigate the potential local regulatory role of CART in GC apoptosis-induced follicular atresia in buffalo, focusing on the modulation of the AKT/GSK3ß/ß-catenin signaling pathways, which are the intracellular signaling pathways involved in cell viability. Our findings revealed increased expression of CARTPT and BAX and decreased levels of AKT, ß-catenin, and CYP19A1 genes in atretic follicles compared to healthy follicles. Subsequently, CART treatment in the presence of FSH inhibited the FSH-induced increase in GC viability by reducing estradiol production and increasing apoptosis. This change was accompanied by an increase in the gene expression levels of both CARTPT and BAX. At the protein level, treatment with CART in the presence of FSH negatively affected the activity of AKT, ß-catenin, and LEF1, while the activity of GSK3ß was enhanced. In conclusion, our study shows how CART negatively influences buffalo GC viability, underlying the modulation of the AKT/GSK3ß/ß-catenin pathway and promoting apoptosis-a key factor in follicular atresia.

Essential/precursor chemical control research: Giommoni's review, understanding multi-replication interrupted time series analysis, and next steps.

Controls on essential/precursor chemicals from commercial companies have been associated with many large downturns in illicit drug markets and attendant problems. My colleagues and I brought this to light in the studies that are the subject of Giommoni's review. McKetin et al. in an earlier review considered several of our studies on chemical controls for methamphetamine, all centered in North America. Giommoni discusses not only those studies but also our later work on chemical controls for cocaine and heroin. This later work evaluates US essential/precursor chemical policies targeting illicit drug producers outside of North America, and it examines impacts on illicit drug availability and use (the studies reviewed by McKetin et al. predominantly focused on outcomes such as drug-related hospitalizations, arrests, and treatment). Giommoni's review is a new resource that will help make the varied topics in essential/precursor chemical control research more accessible to many readers. After noting this, I discuss some common methodological misconceptions about our studies. For example, our studies generally used multi-replication interrupted time series analysis, a research design among the most powerful of all quasi-experimental designs. Authors, however, typically discuss the studies as if they used single-intervention interrupted time series analysis, a less powerful design. Multi-replication and single-intervention interrupted time series analyses also differ regarding likely confounders; awareness of this is critical to accurately assessing our findings and critiquing alternative explanations. Finally, I note that commercial chemical companies function as the silent, albeit usually unwitting, partners in the large-scale production of several illicit drugs, including fentanyl. And many governments are implementing essential/precursor chemical controls to help stymie this partnership. But they are doing so largely without evaluation and study-a poor policy practice. To remedy this, I suggest establishing multi-disciplinary applied research teams to help assess, guide and improve essential/precursor chemical control efforts.

Rapid nanomolar detection of cocaine in biofluids by electrochemical aptamer-based sensor with low-temperature effect for drugged driving screening.

Cocaine is one of the most abused illicit drugs, and its abuse damages the central nervous system and can even lead directly to death. Therefore, the development of simple, rapid and highly sensitive detection methods is crucial for the prevention and control of drug abuse, traffic accidents and crime. In this work, an electrochemical aptamer-based (EAB) sensor based on the low-temperature enhancement effect was developed for the direct determination of cocaine in bio-samples. The signal gain of the sensor at 10 °C was greatly improved compared to room temperature, owing to the improved affinity between the aptamer and the target. Additionally, the electroactive area of the gold electrode used to fabricate the EAB sensor was increased 20 times by a simple electrochemical roughening method. The porous electrode possesses more efficient electron transfer and better antifouling properties after roughening. These improvements enabled the sensor to achieve rapid detection of cocaine in complex bio-samples. The low detection limits (LOD) of cocaine in undiluted urine, 50% serum and 50% saliva were 70 nM, 30 nM and 10 nM, respectively, which are below the concentration threshold in drugged driving screening. The aptasensor was simple to construct and reusable, which offers potential for drugged driving screening in the real world.

Toxicology of anhydroecgonine methyl ester: A systematic review of a cocaine pyrolysis product.

Anhydroecgonine Methyl Ester (AEME), also known as methylecgonidine, is the main pyrolysis product of smoking cocaine (cocaine base paste or basuco, crack, or freebase). This review aims to synthesize the available scientific evidence on the toxicokinetic and toxicodynamic effects of AEME. A search of scientific articles published in Science Direct, SCOPUS, and MEDLINE up to May 2024 was conducted. Twenty-four articles, including 13 experimental animal studies, 2 clinical trials, and 3 observational studies, were reviewed. AEME is readily deposited in the alveoli; its absorption improves in combination with cocaine and has a broad tissue distribution. It is metabolized primarily in the liver, with a half-life of approximately one hour, and is mainly excreted through urine. Moreover, AEME acts as a partial agonist of M1 and M3 muscarinic cholinergic receptors, influences dopaminergic system neuroadaptation, increases the production of reactive oxygen species, imbalances the activity of glutathione-associated enzymes, and reduces melatonin levels, affecting its antioxidant regulatory properties. When combined with cocaine, AEME activates the non-apoptotic pathway of caspase-9 and then, the apoptotic pathway via caspase-8, reducing neuronal viability in half the time of cocaine. AEME plays a significant role in cocaine toxicity and AEME itself.

Adult rat ultrasonic vocalizations and reward: Effects of propranolol and repeated cocaine administration.

BACKGROUND: Mechanisms underlying psychostimulant euphoria remain poorly understood. In adult rats, positive emotional states are associated with alterations in 50-kHz ultrasonic vocalizations (USVs): specifically, "trill" calls are promoted over "flat" calls. Here, we investigated the effects of acute and repeated cocaine administration, and-based on previous findings with amphetamine-their possible dependence on beta-adrenergic receptors. METHODS: Adult male Long-Evans rats received intraperitoneal drug or saline injections before daily USV recording. Fourteen 50-kHz call subtypes were analyzed. In Experiments 1 and 2, cocaine (1-10 mg/kg) and propranolol (10 mg/kg) were tested alone. In Experiment 3, propranolol/cocaine interactions were sought within a conditioned place preference (CPP) procedure. Experiment 4 investigated acute and chronic cocaine effects (Phase 1), and propranolol/cocaine interactions either in an open field (Phase 2) or within a CPP procedure (Phase 3). RESULTS: In drug-naïve animals, cocaine increased the 50-kHz call rate, with sensitization developing rapidly. After more extended exposure, cocaine now also increased the relative prevalence of trill versus flat calls; effects on other subtypes were also revealed. The beta-blocker propranolol prevented neither cocaine CPP nor cocaine effects on USV emission or locomotion but exerted significant USV-related effects when given alone. CPP magnitude and USV-related measures were uncorrelated. CONCLUSIONS: With long-term intraperitoneal administration, cocaine can alter the relative prevalence of several 50-kHz call subtypes; its ability to promote trill versus flat calls, in particular, is consistent with a positive affect interpretation. Cocaine's behavioral effects (i.e., USV-related, locomotor, CPP) appear independent of beta-adrenergic receptor activity.

Granulomatosis With Polyangiitis Presenting As Orbital Apex Syndrome.

Granulomatosis with polyangiitis (GPA) is a rare small-vessel vasculitis that typically presents with a triad of sinonasal, pulmonary, and renal symptoms. Here, we present the case of a 43-year-old female with a history of substance use disorder who presented with vision changes and worsening left eye pain over five days. Previous evaluations raised concerns about GPA versus cocaine-induced vasculitis, but diagnostic confirmation was hindered by a lack of medical follow-up. Prompt multidisciplinary intervention led to significant improvement following steroid therapy and IV antibiotics, and the patient was ultimately diagnosed with a high GPA. This case highlights the complexities involved in diagnosing and managing GPA presenting as orbital apex syndrome, particularly in patients with comorbidities and non-adherence to medical follow-up.

Self-administration acquisition latency predicts locomotor sensitivity to cocaine in male rats.

Individual differences in drug use emerge soon after initial exposure, and only a fraction of individuals who initiate drug use go on to develop a substance use disorder. Variability in vulnerability to establishing drug self-administration behavior is also evident in preclinical rodent models. Latent characteristics that underlie this variability and the relationship between early drug use patterns and later use remain unclear. Here, we attempt to determine whether propensity to establish cocaine self-administration is related to subsequent cocaine self-administration behavior in male Sprague-Dawley rats (n = 14). Prior to initiating training, we evaluated basal locomotor and anxiety-like behavior in a novel open field test. We then trained rats to self-administer cocaine in daily 3 h cocaine (0.75 mg/kg/infusion) self-administration sessions until acquisition criteria (≥30 active lever presses with ≥70 % responding on the active lever in one session) was met and divided rats into Early and Late groups by median-split analysis based on their latency to meet acquisition criteria. After each rat met acquisition criteria, we gave them 10 additional daily cocaine self-administration sessions. We then conducted a progressive ratio, cocaine-induced locomotor sensitivity test, and non-reinforced cocaine seeking test after two weeks of forced abstinence. Early Learners exhibited significantly less locomotion after an acute injection of cocaine, but the groups did not differ in any other behavioral parameter examined. These results indicate that cocaine self-administration acquisition latency is not predictive of subsequent drug-taking behavior, but may be linked to physiological factors like drug sensitivity that can predispose rats to learn the operant task.