In vivo action of phosphatidylserine, amitriptyline and stress on the binding of [3H]imipramine to membranes of the rat cerebral cortex.

Liposomes of bovine brain phosphatidylserine and of phosphatidylcholine were prepared and injected i.p. into rats for 5 days. Another group received i.p. injections of amitriptyline in addition to phosphatidylserine. Subgroups of control and phosphatidylserine-injected rats were submitted to an acute swimming stress for 15 min. The number of [3H]imipramine binding sites in the phosphatidylserine-injected rats, decreased 23% whereas there was no change in the phosphatidylcholine-injected rats. The combination of amitriptyline and phosphatidylserine produced a more marked reduction in [3H]imipramine binding (-47%). Control rats undergoing acute stress showed a 30% decrease in [3H]imipramine binding whereas the stress did not significantly change the control values of the phosphatidylserine-treated animals. These findings are discussed in relation to the known action of phosphatidylserine on several neurotransmitter systems and on the potentiation of antidepressant effects.