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  • Title: Different times of withdrawal from cocaine administration cause changes in muscarinic and dopaminergic receptors in rat premotor cortex.
    Author: Macêdo DS, Sousa FC, Vasconcelos SM, Lima VT, Viana GS.
    Journal: Neurosci Lett; 2001 Oct 26; 312(3):129-32. PubMed ID: 11602327.
    Abstract:
    The present work studied neurochemical changes in rat premotor cortex 30 min, 1 and 5 days after withdrawal from cocaine repeated administration (20 and 30 mg/kg, intraperitoneally, daily for 7 days). Binding assays were performed in 10% homogenates, and ligands used were [(3)H]-N-methylscopolamine, [(3)H]-SCH 23390, and [(3)H]-spiroperidol for muscarinic, D(1)- and D(2)-like receptors, respectively. Levels of cyclic AMP (cAMP) and cyclic guanosine monophosphate (cGMP) were determined using a commercial kit. Scatchard analyses of muscarinic receptors showed an upregulation after 1 and 5 days withdrawal. While D(2)-like receptors were upregulated at all withdrawal periods, D(1)-like receptors were upregulated only at the 30 min withdrawal, and returned to normal levels after 1 day of the last injection. In relation to cAMP levels, the repeated cocaine administration, 1 day after the last injection produced a decrease (around 26%) with both doses, while a 67% increase was seen in cGMP levels with the 30 mg/kg dose. These findings indicate lasting neurochemical changes in premotor cortex caused by cocaine which remained after different withdrawal periods.
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