Immunohistochemical localization of substance P and ACTH-like activity in the central nervous system of the earthworm Lumbricus terrestris L.

The peroxidase-antiperoxidase (PAP) method was used for the immunohistological demonstration of substances P and ACTH in the cerebral and subesophageal ganglia of the earthworm, Lumbricus terrestris L. With rabbit antibody to substance P a positive immunoreaction was found in nerve cells smaller than the type A neurons of the cerebral ganglion. Their perikarya and nerve processes as well as their terminal enlargements in the synaptic zone were immunoreactive. ACTH-like activity was visible in a larger perikaryon type of the A neurons. Their nerve processes did not show any reaction. However, a part of the nerve terminals of the synaptic zone and a few neurons of type B of the cerebral ganglion, further some cells of the subesophageal ganglion reacted positively.