Immunopharmacological studies using 5-hydroxytryptamine antibody.

An antibody to serotonin (5-HT) was tested on several preparations in which 5-HT is considered to be involved. The antibody was capable of effectively competing with 5-HT receptor sites for free molecules of 5-HT. It inhibited the uptake of 3H-5HT by blood platelets and may explain the reduced endogenous 5-HT concentration in blood platelets of immunized rabbits. The decreased platelet content of 5-HT was substantiated by electron microscopic studies which showed a reduction in the number of 5-HT-containing subcellular storage organelles in platelets from these animals. The 5-HT antibody inhibited the 5-HT-induced contraction of aortic strips in a tissue bath preparation. When given intraventricularly, it inhibited for a time the sedative actions of reserpine thus adding new evidence to the often postulated role of 5-HT in the actions of reserpine.