Proctolin immunoreactive elements in the nervous system of earthworm (Lumbricus terrestris).

Proctolin (H-Arg-Try-Leu-Pro-Thr-OH) immunoreactive elements in the nervous system of earthworm (Lumbricus terrestris, L.) were detected in paraffin sections using peroxidase-antiperoxidase method. Each part of the central nervous system contains proctolin immunoreactive cell bodies. The nerve cells, according to their locations are motoneurons, sensory neurons as well as interneurons. A part of the sensory epithelial cells of the body surface are proctolin immunoreactive, too. The body wall muscles receive a rich proctolin immunoreactive network. It is supposed that proctolin acts as a neuromodulator in the nervous system of Lumbricus terrestris.