A single pretreatment with MK-801 or cocaine enhances their locomotor stimulant effects in rats.

Autor: O'Neill MF; Eli Lilly and Company, Lilly Research Centre, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK. oneill_michael_f@lilly.com, Sanger GJ
Jazyk: angličtina
Zdroj: Brain research [Brain Res] 1999 Jul 10; Vol. 834 (1-2), pp. 103-11.
DOI: 10.1016/s0006-8993(99)01580-2
Abstrakt: A single dose of MK-801 (1.0 mg/kg, s.c.) induces an enhanced locomotor response to a subsequent lower dose of MK-801 (0.3 mg/kg) administered 4, 7 or 14 days later in young adult rats (>90 days). MK-801 (1.0 mg/kg) administration did not significantly enhance the effects of cocaine (10, 20 mg/kg) administered 7 days later. Cocaine (20 mg/kg) enhanced the effect of a subsequent dose of 10 mg/kg cocaine, but did not significantly alter the response to a higher dose cocaine (20 mg/kg) or of MK-801 (0.1 or 0.3 mg/kg) again given 7 days later. MK-801 (1.0 mg/kg) did not significantly enhance the locomotor response to a second dose of MK-801 (0.3 mg/kg) in 28-day-old rats tested 7 days after the initial dose, but did enhance the effects of a lower (0.1 mg/kg) dose. These findings indicate that even a single dose of a stimulant such as MK-801 and cocaine can induce enduring changes in sensitivity to subsequent doses of the same stimulants in young adult rats. The lack of significant effects seen in cross-sensitization studies suggests that separate mechanisms maybe involved in the sensitization to cocaine and MK-801. The more pronounced enhancement of activity in the older animals is in accord with previous findings that sensitization processes are developmentally regulated.
(Copyright 1999 Elsevier Science B.V.)
Databáze: MEDLINE
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