Neuropeptide-dopamine interactions. II. Cyclo (His-Pro) augmentation of amphetamine- but not apomorphine-induced stereotypic behavior.
Histidyl-proline diketopiperazine (cyclo [His-Pro]) not only exists in the basal ganglia of rodents, monkeys, and humans, but also exhibits a variety of biologic activities, some of which appear to be mediated via dopaminergic mechanisms. We investigated the potential modulation by cyclo (His-Pro) of amphetamine- and apomorphine-induced stereotypic behavior, a behavior that is associated with the activation of postsynaptic dopamine receptor. Administration of amphetamine to rats resulted in a dose-dependent increase in stereotypic behavior that was further augmented if animals were pretreated with cyclo (His-Pro). Although apomorphine also led to a dose-related progression in the stereotypic behavior, the apomorphine effects were not modified by cyclo (His-Pro) pretreatment. We conclude that cyclo (His-Pro) either acts indirectly at the presynaptic dopamine site or modulates other neurotransmitters to potentiate actions of amphetamine.
Prasad
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Department of Medicine, Louisiana State University Medical Center, New Orleans 70112.
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D004357:Drug Synergism; D008297:Male; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013239:Stereotyped Behavior / Q000187:drug effects*
D010456:Peptides, Cyclic; D010879:Piperazines; D011954:Receptors, Dopamine; D000661:Amphetamine; D001058:Apomorphine; C015924:histidyl-proline diketopiperazine