Effects of beta-casomorphin derivatives on gastrointestinal transit in mice.

Some D-amino acid-substituted derivatives of beta-casomorphin (CM) were found to exhibit a special affinity to central opiate receptors. Concerning their affinity to peripheral opiate receptors our knowledge is still limited. The results of our experiments indicate that CM derivatives interfere with peripheral opiate receptors and that there is a close connection with the affinity to different subtypes of this receptor.