Phosphatidylserine increases acetylcholine release from cortical slices in aged rats

Acetylcholine release was investigated in cortical slices superfused with choline-enriched Krebs solution containing physostigmine. Slices were prepared from 3 and 24 month old rats treated with either Tris buffer or sonicated suspensions of phosphatidylserine and phosphatidylcholine in Tris buffer. Slices were electrically stimulated at frequencies of 1, 2 and 5 Hz for 5 min periods preceded and followed by rest periods. ACh content of the superfusate was quantified by bioassay. In the 24 month old rats treated with Tris buffer, acetylcholine release, at all frequencies tested, was approximately 50% lower than that in the 3 month old rats. On the contrary, no significant decrease in ACh release was found in the 24 month old rats treated for 30 days with phosphatidylserine (15 mg/kg IP). The same treatment did not increase acetylcholine release in 3 month old rats. Acetylcholine release in 24 month old rats receiving a single administration of phosphatidylserine (15 mg/kg IP) or phosphatidylcholine (15 mg/kg IP) for 30 days was as low as in the 24 month old rats receiving the Tris buffer only. It is proposed that the chronic phosphatidylserine treatment may reduce the age-induced decrease in acetylcholine release by acting on the stimulus-secretion coupling mechanism.