TY - JOUR
T1 - Morphine-induced long-term sensitization to the locomotor effects of morphine and amphetamine depends on the temporal pattern of the pretreatment regimen
AU - Vanderschuren, L.J.M.J.
AU - Tjon, G.H.K.
AU - Nestby, P.
AU - Mulder, A.H.
AU - Schoffelmeer, A.N.M.
AU - de Vries, T.J.
PY - 1997/7/3
Y1 - 1997/7/3
N2 - 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 pre-treatment is far more effective in inducing long-term behavioural sensitization than chronic morphine pre- treatment.
AB - 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 pre-treatment is far more effective in inducing long-term behavioural sensitization than chronic morphine pre- treatment.
KW - Amphetamine
KW - Behavioural sensitization
KW - Locomotor activity
KW - Pretreatment regimen Morphine
KW - Time course
UR - http://www.scopus.com/inward/record.url?scp=0030949544&partnerID=8YFLogxK
U2 - https://doi.org/10.1007/s002130050273
DO - https://doi.org/10.1007/s002130050273
M3 - Article
C2 - 9201798
SN - 0033-3158
VL - 131
SP - 115
EP - 122
JO - Psychopharmacology
JF - Psychopharmacology
IS - 2
ER -