Effects of cholecystokinin tetra and octa peptides on locomotor activity in mice.
Intraperitoneal injection of cholecystokinin octapeptide (10 and 100 micrograms/kg, i.p.), but not the tetra-peptide (1 mg/kg, i.p.), into mice significantly reduced spontaneous locomotor activity in a dose-dependent manner. The increase in locomotor activity induced by methamphetamine (1 mg/kg, i.p.) and thyrotropin-releasing hormone (5 mg/kg, i.p.) was significantly reduced by cholecystokinin peptides. However, the inhibitory effects of these peptides differed. Neither the tetra nor octa peptide influenced the increased locomotor activity induced by nomifensine (5 mg/kg, i.p.), apomorphine (3 mg/kg, i.p.) or scopolamine (2 mg/kg, i.p.). Thus, these cholecystokinin peptides seem to selectively antagonize increased locomotor activity via the presynaptic dopaminergic system.
D000818:Animals; D004435:Eating / Q000187:drug effects; D005106:Exploratory Behavior / Q000187:drug effects; D005755:Gastrins / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D012844:Sincalide / Q000494:pharmacology*; D013758:Tetragastrin / Q000494:pharmacology*
D005755:Gastrins; D013758:Tetragastrin; D012844:Sincalide