Influence of modified casomorphins on yawning behavior of rats.
Apomorphine-induced yawning was completely suppressed in animals treated with 5 nmol [D-Pro4]casomorphin (CM) (ICV), 10 nmol [D-Phe3]CM (ICV) or 10 nmol [D-Pip4]CM (ICV). The apomorphine-induced yawning was also decreased, by des-Tyr analogs, but only by about 50%. Physostigmine (0.15 mg/kg, IP) induced yawning. The physostigmine-induced yawning was suppressed by 5 nmol [D-Pro4]CM and 10 nmol [D-Phe3]CM. Both [des-Tyr-D-Phe3]CM and [des-Tyr-D-Pip4]CM were without effect, whereas [des-Tyr-D-Pro4]CM increased significantly the physostigmine-induced yawning. The results suggest that dopaminergic transmission can be modulated by beta-casomorphin derivatives, thus resulting in a decrease in yawning. In the case of the des-tyrosine derivatives, we can assume a dopaminergic modulation, too. An increase in serotonergic activity might be supposed for [des-Tyr-D-Pro4]CM.
Rüthrich
H L
HL
Institute of Pharmacology and Toxicology, Medical Academy, Magdeburg, FRG.
Grecksch
G
G
Matthies
H
H
D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000494:pharmacology*; D004723:Endorphins / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000494:pharmacology*; D010830:Physostigmine / Q000494:pharmacology*; D051381:Rats; D015000:Yawning / Q000187:drug effects*
D002364:Caseins; D004723:Endorphins; D010446:Peptide Fragments; C021968:beta-casomorphins; C059556:beta-casomorphin, des-Tyr-; D010830:Physostigmine