Influence of beta-casomorphins on apomorphine-induced hyperlocomotion.
Derivatives of beta-casomorphin Tyr-Pro-Phe-Pro-Gly and their des-Tyr1-derivatives were investigated on the model of apomorphine-induced hyperlocomotion (1 mg/kg = 3 microM/kg, IP). D-Pip4 CM 5 (5 nM) inhibited the apomorphine hypermotility completely, while D-Phe3 CM 5 (5 nM) and D-Pro4 CM 5 (5 nM) decreased it only to about 50%. The normal exploration was nearly completely inhibited by D-Pro4 CM 5 (40 nM), by D-Pip4 CM 5 (5 nM) depressed to 20%, and by D-Phe3 CM 5 (10 nM) to 35%. The maximum inhibition of apomorphine-induced hyperlocomotion by the des-Tyr-casomorphin derivatives was about 50%. The dose-response curves were U-shaped. The exploratory activity was not significantly influenced. The mode of action and the involvement of different neurotransmitter systems in the inhibitory effect of beta-casomorphin derivatives on apomorphine hyperlocomotion are discussed.
Rüthrich
H L
HL
Institute of Pharmacology and Toxicology, Medical Academy, Magdeburg, Germany.
Grecksch
G
G
Matthies
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001058:Apomorphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000494:pharmacology*; D006220:Haloperidol / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D008969:Molecular Sequence Data; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D004723:Endorphins; C021968:beta-casomorphins; D006220:Haloperidol; D001058:Apomorphine