Morphine-induced long-term sensitization to the locomotor effects of morphine and amphetamine depends on the temporal pattern of the pretreatment regimen

The development of behavioural sensitization is thought to depend on the dose and temporal pattern of drug treatment. Previous studies have shown that two distinct morphine pretreatment regimens cause different long-term neuroadaptations in rat striatum. Therefore, in the present study the ability o...

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Bibliographic Details
Published in:Psychopharmacologia 1997-05, Vol.131 (2), p.115-122
Main Authors: VANDERSCHUREN, L. J. M. J, TJON, G. H. K, NESTBY, P, MULDER, A. H, SCHOFFELMEER, A. N. M, DE VRIES, T. J
Format: Article
Language:English
Subjects:
Amphetamine - pharmacology
Amphetamines
Animals
Biological and medical sciences
Drug Administration Schedule
Drug toxicity and drugs side effects treatment
Locomotion - drug effects
Male
Medical sciences
Miscellaneous (drug allergy, mutagens, teratogens...)
Morphine
Morphine - pharmacology
Neostriatum
Pharmacology. Drug treatments
Rats
Rats, Wistar
Sensitivity and Specificity
Time Factors
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Summary:The development of behavioural sensitization is thought to depend on the dose and temporal pattern of drug treatment. Previous studies have shown that two distinct morphine pretreatment regimens cause different long-term neuroadaptations in rat striatum. Therefore, in the present study the ability of these pretreatment regimens to induce long-term behavioural sensitization was investigated. One pretreatment regimen, termed "chronic", consisted of three daily injections, for 5 days, with escalating doses (10-50 mg/kg) of morphine, and the other, termed "intermittent", of 14 daily injections with morphine (10 mg/kg). Both intermittent and chronic morphine pretreatment caused sensitization to the locomotor effects of morphine, 3 weeks post-treatment, although the former induced a far greater level of sensitization. Moreover, 3 weeks post-treatment, intermittent, but not chronic, morphine pretreatment induced cross-sensitization to the locomotor stimulant effects of amphetamine. Behavioural sensitization following intermittent morphine pretreatment was clear-cut both 1 day and 3 weeks post-treatment, while after 9 weeks, the locomotor effects of morphine were still slightly augmented. It is concluded that intermittent morphine pretreatment is far more effective in inducing long-term behavioural sensitization than chronic morphine pretreatment.
ISSN:0033-3158
1432-2072
DOI:10.1007/s002130050273