[Regulation of ACTH4-9 analogue on the Ca2+ level of mouse hippocampal synaptosomes]

The effect of ACTH4-9 analogue Org2766 on the [Ca2+]i level of mouse hippocampal synaptosomes was studied. Synaptosomal free calcium concentration ([Ca2+]i) and 45Ca2+ uptake were measured respectively by spex cation measurement system and Beckman LS-9800 liquid scintillation spectrometer. Low dose of Org2766 did not change synaptosomal [Ca2+]i level, but decreased 45Ca2+ uptake. High dose of Org2766 increased [Ca2+]i without affecting 45Ca2+ uptake. Low dose of Org2766 inhibited the anisomysin-induced increase of synaptosomal [Ca2+]i while high dose had no effect. These results suggest that the regulation of Org2766 on hippocampal synaptosomal Ca2+ level may be achieved by inhibiting the Ca2+ influx and increasing the release of synaptosomal calcium pool.