benzoylecgonine and Disease-Models--Animal

A recombinant humanized anticocaine monoclonal antibody, h2E2, has shown potential in the preclinical phases for the treatment of cocaine abuse. The standard tests for cocaine usage are the detection of benzoylecgonine (BE) and cocaine in the urine. This includes workplace drug screens as well as in clinical trials for potential treatments of cocaine abuse. By sequestering cocaine into the plasma compartment, h2E2 prevents cocaine from entering the brain. Due to the altered disposition of cocaine in the presence of h2E2, we investigated the effects of h2E2 on cocaine and metabolite levels in the urine of rats to clarify the use of BE as an endpoint measurement for effectiveness in future clinical trials. The urine concentrations of cocaine and metabolites were considerably altered in the presence of h2E2. After a single injection of h2E2 (120 mg/kg) and cocaine hydrochloride (0.56 mg/kg), the concentration of cocaine and BE excreted into the urine of rats decreased by 92% and 91%, respectively, from vehicle controls. Due to the significant decrease in urinary excretion, BE is not an appropriate indicator of cocaine usage in the presence of h2E2. Another endpoint measurement must be selected for the measurement of cocaine usage in the upcoming clinical trials of h2E2. In contrast to the effects on cocaine and BE urinary excretion, there was a 3-fold increase in ecgonine methyl ester (EME) in the presence of h2E2. Therefore, we conclude that EME is a more appropriate measurement of cocaine intake in the presence of h2E2.

Topics: Animals; Antibodies, Monoclonal, Humanized; Cocaine; Cocaine-Related Disorders; Disease Models, Animal; Humans; Male; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Renal Elimination; Substance Abuse Detection

In humans, adolescence is a period of heightened propensity to develop cocaine addiction. It is unknown whether this is attributable to greater access and exposure to cocaine at this age, or whether the adolescent brain is particularly vulnerable to the addictive properties of cocaine. Here, we subjected male adolescent (P42) and adult (∼P88) rats to a wide range of cocaine self-administration procedures. In addition, to determine whether behavioral differences are associated with developmental differences in dopaminergic activity, we examined and manipulated the activity of dopamine neurons. Relative to adults, adolescent rats took cocaine more readily, were more sensitive to lower doses, showed greater escalation of cocaine intake, and were less susceptible to increases in price (i.e., were more "inelastic"). In parallel, adolescents also showed elevated activity of ventral tegmental area dopamine neurons, a feature known to be associated with increased self-administration behavior. Pharmacological manipulation of dopamine D2 receptor function with quinpirole (agonist) or eticlopride (antagonist), to alter dopamine neuron activity, eliminated age differences in cocaine self-administration. These data suggest a causal relationship between behavioral and electrophysiological determinants of cocaine addiction liability. In conclusion, adolescents show behavioral and electrophysiological traits of heightened addiction liability.

Topics: Action Potentials; Age Factors; Aging; Analysis of Variance; Animals; Animals, Newborn; Behavior, Animal; Brain; Cocaine; Cocaine-Related Disorders; Conditioning, Operant; Disease Models, Animal; Dopamine Agonists; Dopamine Antagonists; Dopamine Uptake Inhibitors; Dopaminergic Neurons; Dose-Response Relationship, Drug; Male; Quinpirole; Rats; Rats, Sprague-Dawley; Reinforcement Schedule; Salicylamides; Self Administration; Time Factors; Ventral Tegmental Area

We employed a cocaine intravenous self-administration model based on positive reinforcement of animals' instrumental reactions (i.e., lever pressing) rewarded by a dose of the drug. We also carried out simultaneous characterization of the pharmacokinetics of cocaine and its metabolites in rats during withdrawal; in this part of the experiments, we investigated the cocaine (2 mg/kg, iv)-induced changes in the distribution, rate constant, clearance and t₁/₂ of the parent drug and its metabolites in different structures of the brain and in peripheral tissues.. By using liquid chromatography-tandem mass spectrometry (LC/MS/MS) we measured the levels of cocaine and its major metabolites.. Our results demonstrate differences in the levels of cocaine after cocaine self-administration in the rat, with the highest concentration seen in the striatum and the lowest in the cerebellum. Cocaine metabolites determined in the rat brain remained at very low levels (benzoylecgonine), irrespectively of the brain area, whereas the norcocaine concentration varied from 1.56 μg/g (the nucleus accumbens) to 2.73 μg/g (the striatum).. A tandem LC/MS/MS is a valid method for evaluation of brain and peripheral levels of cocaine and its metabolites. Our results demonstrate brain area-dependent differences in the levels of cocaine after its self-administration in the rat. There were also differences in pharmacokinetic parameters among the brain areas and peripheral tissues following a bolus iv injection of cocaine to rats withdrawn from cocaine; among brain structures the slowest metabolic rate was detected for the striatum.

Topics: Animals; Biotransformation; Brain; Central Nervous System Stimulants; Chromatography, Liquid; Cocaine; Cocaine-Related Disorders; Disease Models, Animal; Half-Life; Injections, Intravenous; Kidney; Liver; Male; Metabolic Clearance Rate; Myocardium; Rats; Rats, Wistar; Reproducibility of Results; Self Administration; Substance Withdrawal Syndrome; Tandem Mass Spectrometry; Tissue Distribution

It has frequently been reported that a high percentage of individuals, identified as either alcohol- or cocaine-dependent, concurrently abuse both drugs. The experiments reported here represent a continuing effort to develop an animal model to predict the effects of a potential pharmacotherapeutic agent on concurrently available oral ethanol and cocaine. These experiments utilized drinkometer circuitry to assess the effects of gamma-vinyl-GABA (GVG), a gamma-aminobutyric acid (GABA) transaminase inhibitor, on the consumption and temporal pattern of responses for orally self-administered ethanol and cocaine. The results of these experiments showed that GVG, at doses of 100, 200 and 300 mg/kg, reduced both ethanol and cocaine consumption in a dose-related manner. When compared to vehicle, GVG at all doses significantly reduced ethanol consumption while consumption of cocaine was significantly reduced only at 300 mg/kg. This is consistent with data showing that GVG reduces consumption of these drugs when administered alone and data showing that GVG is more potent in reducing ethanol-induced compared to cocaine-induced extracellular dopamine in the nucleus accumbens. Analysis of the temporal pattern of drinking across the session suggests that GVG's effects are due to a disruption of the reinforcing properties of ethanol and cocaine rather than a more general reduction in motor behavior. These data suggest that GVG has potential for clinical use in populations that abuse either alcohol or cocaine alone or in combination.

Topics: Alcohol Drinking; Animals; Behavior, Addictive; Cocaine; Cocaine-Related Disorders; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Male; Rats; Rats, Wistar; Self Administration; Vigabatrin

The accurate interpretation of analytical results from hair testing for drugs of abuse continues to be a complex and difficult problem since many questions still remain unanswered. In this paper an animal model was developed to ascertain the time course for the appearance and disappearance of cocaine and its metabolite benzoylecgonine (BE) in hair. Female Fauve Bourgogne red-haired rabbits (n = 6) were intraperitoneally administered a single dose of cocaine at 5 mg/kg. Animal hair was shaved just before drug administration and the newly grown back hair was subsequently shaved and collected daily over a period of two weeks. Samples were analyzed for cocaine and BE by gas chromatography-mass spectrometry (GC-MS). The profiles were quite similar for parent drug and metabolite. Cocaine and BE appeared in the first sampling (day 1), with peak concentration appearing that same day. 1.01 ng/mg and 0.51 ng/mg for cocaine and BE, respectively. Levels declined rapidly on day 2, remaining detectable for ten days after drug administration. This study demonstrates that the initial incorporation of cocaine compounds in rabbit hair is very rapid (24 h). A small fraction of the drug is detected ten days after exposure, at a time when concentrations in other biological specimens (blood or urine) are not detectable.

Topics: Animals; Cocaine; Disease Models, Animal; Female; Gas Chromatography-Mass Spectrometry; Hair; Narcotics; Rabbits; Sensitivity and Specificity; Substance Abuse Detection

Prenatal cocaine (CC) exposure may result in increased fetal loss, growth retardation, altered neurodevelopment, and sudden infant death syndrome (SIDS). We sought to establish an animal model for prenatal cocaine exposure which (1) would allow us to distinguish the direct effects from the indirect and nutritional effects of the drug, and (2) might be used to address questions of cocaine's toxicity, specifically to the developing respiratory control system. The study design included 38 New Zealand White rabbit does among CC, pair-fed (PF), and free-fed (FF) groups. Miniosmotic pumps were implanted in each doe on day 10 of timed gestation providing continuous subcutaneous administration of either 30 mg/kg/day of cocaine HCl in H2O (CC) or sterile H2O alone (PF and FF). Mean (SEM) plasma cocaine concentration was 1.71 +/- 0.21 mumol/l (519.4 +/- 64.4 ng/ml). Pregnancy outcome compared for incidence of stillbirth, maternal death, spontaneous abortion, and gross malformation among 211 pups was significant only for increased stillbirths among CC pups (18%, p less than 0.04) as compared to PF (6%) and FF pups (7%). External and renal malformation and postnatal weight, crown-rump length, and snout-occiput head circumference for pups aged 4 and 5 days of age did not differ among groups. The direct effects of prenatal cocaine evaluated in our model do not reproduce the altered perinatal outcome observed among humans. However, our results do not determine if physiologic function has been altered. Investigation of the physiologic and pathologic abnormalities that are relevant to this human condition, specifically to the developing respiratory control system, should add clarity to the mechanism of action of cocaine during pregnancy.

Topics: Abortion, Spontaneous; Animals; Animals, Newborn; Cocaine; Disease Models, Animal; Female; Fetal Death; Fetal Growth Retardation; Fetus; Humans; Infant, Newborn; Pregnancy; Pregnancy Outcome; Prenatal Exposure Delayed Effects; Rabbits