Opioid peptides increase calcium uptake by synaptosomes from brain regions.

The fast-phase calcium uptake by depolarized hippocampal synaptosomes was increased significantly following treatment with 10 nM or 10 microM D-Ala2,D-Leu5-enkephalin (DADLE). No significant changes of calcium uptake by depolarized cortical or striatal synaptosomes were observed for 10 nM or 10 microM treatment with this enkephalin analog. Dynorphin 1-17 analog at 10 nM produces a significant increase in calcium uptake by depolarized striatal synaptosomes. beta-Endorphin and the dynorphin 1-13 fragment analog (10 nM) caused no significant change in the calcium uptake by depolarized synaptosomes from any of the three brain regions. However, calcium uptake by non-depolarized striatal and cortical synaptosomes was increased significantly in the presence of 10 nM beta-endorphin and DADLE. Opioid peptide action on neural calcium uptake is complex and appears to vary somewhat from one brain region to another.