Cortical [alpha]1-adrenergic regulation of acute and sensitized morphine locomotor effects

Inserm U.114, Collège de France, 11, Place Marcelin Berthelot, 75231 Paris Cedex 05, France.
Neuroreport (Impact Factor: 1.64). 11/2001; 12(16):3483-3486.

ABSTRACT The role of α1-adrenergic transmission was tested on locomotor effects of acute or repeated morphine (5 mg/kg, i.p.) administration. Prazosin, an α1-adrenergic antagonist, administered 30 min before morphine, either systemically (0.5 mg/kg, i.p.) or locally and bilaterally into the prefrontal cortex (200 pmol/side) reduced the stimulatory influence of morphine on locomotion. The progressive increase of the locomotor response induced by repeated morphine injections was blocked by a prazosin pretreatment but not the behavioral sensitization on the test day. These data suggest that blockade of cortical α1-adrenergic receptors reduces the expression of acute and sensitized locomotor responses to morphine, but does not prevent the induction of behavioral sensitization.

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