The biotinylation of the rabbit serotonin antibody and its application to immunohistochemical studies using the two-step ABC method.

A newly modified and improved immunohistochemical method was devised for the demonstration of the serotonin neuron system in the central nervous system of the rabbit using serotonin antibody obtained by the immunization of rabbits, i.e., the biotinylation of serotonin antibodies, and the application of the two-step avidin-biotin-peroxidase complex (ABC) method. Using this technique, high background staining and nonspecific reactions were avoided, and extremely clear preparations were produced. The serotonin neurons of rabbit brain, which have a Golgi-like appearance, were followed to the fine terminals. This technique were also applied for electron microscopy, and satisfactory results concerning the submicroscopical distribution of serotonin were obtained.