Involvement of Protein Kinase C in CCK‐8 induced Oxytocin Release in rat spinal cord

Abstract

We have previously reported that 56 mM KCl could induce release of Oxytocin (OT) from synaptosomes prepared from rat spinal cord. To determine if a physiological stimulus such as CCK-8 could induce release of the hormone from spinal cord synaptosomes, the present series of experiments were performed. Purified synaptosomes were prepared using 23%, 15%, 10% and 3% percoll solution. When rat spinal cord synaptosomes were incubated with CCK-8, the release of OT occurred in dose dependent manner. Thus, in the presence of 100 nM, 300 nM, 500nM and 1μM CCK-8, the hormone release was 160%, 175%, 190% and 500% respectively. In an effort to determine if Protein Kinase C (PKC) pathway is involved in the release of oxytocin by CCk-8, we incubated the synaptosomal preparations with CCK-8 and H-7, Dihydrochloride, an inhibitor of PKC. In these experiments, the CCK-8 induced OT release was reduced by 50%. Taken together, these results suggest that CCK-8 might be involved in the release of Oxytocin from the spinal cord and that PKC is involved in the release process.