The effects of continuous cocaine duration on the induction of behavioral tolerance and dopamine autoreceptor function
| Autor: | Gene Castro, Jennifer Konen, Craig Hillburn, Gail Pinto, Rachel Cayse, George R King, Sophie Tran, Wees Love |
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| Rok vydání: | 2002 |
| Předmět: |
Agonist
Male medicine.medical_specialty Quinpirole Time Factors medicine.drug_class Pharmacology Motor Activity Dopamine agonist Receptors Dopamine Rats Sprague-Dawley Cocaine Dopamine Internal medicine medicine Animals Autoreceptors Behavior Animal business.industry Drug Tolerance Rats Substance Withdrawal Syndrome Endocrinology Dopamine receptor Toxicity Catecholamine Autoreceptor business medicine.drug |
| Zdroj: | European journal of pharmacology. 446(1-3) |
| ISSN: | 0014-2999 |
| Popis: | The current experiment evaluated the dose-dependent nature of the induction of behavioral tolerance, and changes in dopamine autoreceptor function, by continuously administering different doses of cocaine. For all experiments, rats were exposed to a 14-day pretreatment regimen involving the continuous administration of either 0, 5, 10, 20, or 40 mg/kg/day cocaine. All subjects were then withdrawn from the pretreatment regimen for 7 days. The subjects were placed in activity monitors, and ambulation measured. In experiment 1, the subjects were challenged with 0.0, 7.5, or 15.0 mg/kg i.p. cocaine on day 7 of withdrawal from the continuous cocaine administration regimen. The results indicated that all continuous cocaine doses induced significant tolerance to the 15.0 mg/kg cocaine challenge, relative to the control group. Furthermore, the 5.0 mg/kg/day group exhibited significantly less tolerance than the 40.0 mg/kg/day group. In experiment 2, the subjects were challenged with 0.0, 0.063, or 0.125 mg/kg quinpirole. The results indicated that the 0.063-mg/kg quinpirole challenge inhibited activity, while the 0.125 mg/kg quinpirole challenge enhanced behavior. The results further suggested that the inhibition of behavior was greater in the cocaine-pretreated subjects than in the saline control group. In experiment 3, the subjects were challenged with the same doses of quinpirole in combination with 15 mg/kg i.p. cocaine. The low quinpirole challenge dose inhibited cocaine-induced hyperactivity, while the higher challenge dose enhanced cocaine-induced hyperactivity. The results suggest that the induction of tolerance by continuous cocaine administration is dose-dependent. Continuous cocaine administration did induce dopamine autoreceptor supersensitivity. However, different continuous cocaine doses did not induce differential degrees of dopamine autoreceptor supersensitivity. |
| Databáze: | OpenAIRE |
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