Morphine-induced long-term sensitization to the locomotor effects of morphine and amphetamine depends on the temporal pattern of the pretreatment regimen (original) (raw)
Abstract
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.
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Authors and Affiliations
- Research Institute Neurosciences Vrije Universiteit, Department of Pharmacology, Faculty of Medicine, Free University, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands Fax (+31) 20/ 444-8100, e-mail: ljmj.vanderschuren.pharm@med.vu.nl, , , , , , NL
L. J. M. J. Vanderschuren, Guno H. K. Tjon, Patrizia Nestby, Arie H. Mulder, Anton N. M. Schoffelmeer & Taco J. De Vries
Authors
- L. J. M. J. Vanderschuren
- Guno H. K. Tjon
- Patrizia Nestby
- Arie H. Mulder
- Anton N. M. Schoffelmeer
- Taco J. De Vries
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Received: 1 July 1996/Final version: 12 December 1996
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Vanderschuren, L., Tjon, G., Nestby, P. et al. Morphine-induced long-term sensitization to the locomotor effects of morphine and amphetamine depends on the temporal pattern of the pretreatment regimen.Psychopharmacology 131, 115–122 (1997). https://doi.org/10.1007/s002130050273
- Issue date: May 1997
- DOI: https://doi.org/10.1007/s002130050273