The effect of systemic injection of cyclosporin A on the phosphorylation of the PKC substrates MARCKS and GAP43 in the rat hippocampus.

Cyclosporin A (CsA) is an inhibitor of calcineurin, a calcium/calmodulin dependent serine/threonine phosphatase. Protein kinase C (PKC) is a family of serine/threonine kinases. Both calcineurin and PKC are implicated in psychiatric diseases and the therapeutic mechanisms of treatment agents. It has been reported that calcineurin interacts with components of PKC signaling pathways. We administrated 50mg/kg CsA into rats by intraperitoneal injection and examined the acute effect of single systemic CsA on the locomotor activity of rats and the phosphorylation of PKC and its substrates GAP43 and MARCKS. Systemic CsA increased locomotor activity beginning 1h after injection. The immunoreactivity of p-MARCKS(S152/156) was higher in the CsA group 1h after injection, whereas p-GAP43(S41) immunoreactivity was increased by CsA after 5h. The immunoreactivity of p-PKC pan was increased by CsA at both 1 and 5h after administration. Our data suggest that activation of the PKC pathway might be related to CsA-induced hyperlocomotion.