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Eur J Pharmacol. 1997 Oct 22;337(2-3):161-4.

Fluoxetine attenuates morphine-induced locomotion and blocks morphine-sensitization.

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Biopsychology Section, Clarke Institute of Psychiatry, Toronto, Ontario, Canada.


Repeated morphine treatments result in sensitization, an increase in the efficacy of morphine to stimulate locomotor activity. study examined the effects of increasing serotonin (5-hydroxytryptamine, 5-HT) transmission on morphine-sensitization. For five days rats were administered saline or 5.0 mg/kg fluoxetine prior to treatment with saline or 5.0 mg/kg morphine. Twenty-one days later, rats were tested for their locomotor response to 2.0 mg/kg morphine. Fluoxetine treatment attenuated the locomotor activating effect of acute morphine treatments and blocked the sensitized response to the morphine challenge. These results indicate that increased 5-HT transmission attenuates the locomotor stimulating effects of morphine and prevents the development of morphine-sensitization.

[Indexed for MEDLINE]

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