Lack of cross-sensitization between the locomotor-activating effects of bromocriptine and those of cocaine or heroin.
Rats were given daily injections of bromocriptine (5.0 mg/kg IP) or vehicle either in the home cage or in a test box equipped with photocells to measure locomotion. The animals were then tested in the photocell boxes for their locomotor response to cocaine (10.0 mg/kg IP), heroin (0.5 mg/kg IP), or quinpirole (0.1 mg/kg IP). Repeated bromocriptine in the test box but not in the home cage caused progressive increases in sensitivity to the locomotor-stimulating effects of bromocriptine and increases in the subsequent sensitivity to quinpirole but caused only trivial signs of cross-sensitization to cocaine or heroin. Cross-sensitization to quinpirole was temporary; responsiveness to quinpirole decreased with further quinpirole injections. Lack of significant cross-sensitization between bromocriptine and either cocaine or heroin and lack of permanence of the cross-sensitization between bromocriptine and quinpirole raise questions as to the biological basis of psychomotor stimulant sensitization.
Hoffman
D C
DC
Department of Psychology, Concordia University, Montreal, Canada.
Wise
R A
RA
D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D003463:Cues; D018491:Dopamine Agonists / Q000494:pharmacology; D004777:Environment; D004873:Ergolines / Q000494:pharmacology; D003932:Heroin / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D019257:Quinpirole; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000819:agonists
D018491:Dopamine Agonists; D004873:Ergolines; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D001971:Bromocriptine; D003932:Heroin; D003042:Cocaine