Márta Szelier

Distribution of PACAP-like immunoreactivity in the nervous system of oligochaeta.

The marked similarity between the primary structures of human, other vertebrate, and the invertebrate tunicate PACAP suggests that PACAP is one of the most highly conserved peptides during the phylogeny of the metazoans. We investigated the distribution of PACAP-like immunoreactivity in the nervous system of three oligochaete (Annelida) worms with immunocytochemistry. The distribution pattern of immunoreactivity was similar in all three species (Lumbricus terrestris, Eisenia fetida, and Lumbricus polyphemus). The cerebral ganglion contains numerous immunoreactive cells and fibers. A few cells and fibers were found in the medial and lateral parts of the subesophageal and ventral cord ganglia. In the peripheral nervous system, immunoreactivity was found in the enteric nervous system, in epidermal sensory cells, and in the clitellum.

Distribution of FMRFamide-like immunoreactivity in the nervous system of Lumbricus terrestris

Abstract.The distribution of FMRFamide-like immunoreactive cell bodies and fibers in the nervous system of the earthworm Lumbricus terrestris has been studied by means of immunocytochemistry. The cerebral ganglion contains 150–170 immunoreactive nerve cells that are organized into six major groups in the rostral and five major groups in the caudal part of the ganglion; 160–180 immunoreactive nerve cells are present in the subesophageal ganglion, and 80–90 in the ventral cord ganglia. Immunoreactive neurons of the subesophageal and the ventral cord ganglia show similar distributions, in that FMRFamide-like immunoreactive cells form a ventromedial and a lateral cell group. Neuropil in all parts of the central nervous system shows intensively stained varicose and non-varicose fibers. Each segmental nerve contains FMRFamide-like immunoreactive fibers that can partly be traced to the two muscle layers of the body wall, and a fine immunoreactive network lies among the muscle fibers. A similar network is found in the wall of the alimentary canal. Immunopositive perikarya and fibers have been detected in the prostomial nerves, in the stomatogastric system. Some epithelial cells of the body wall are also immunopositive. The morphological characteristics and localization of FMRFamide immunoreactive neurons suggest that they may be involved in: (1) central integratory processes; (2) neuromuscular regulation in both the body wall and enteric system; (3) sensory processes.

Co-localization of serotonin and FMRFamide-like immunoreactivities in the central nervous system of the earthworm, Eisenia fetida

In the present study co-localization of serotonin and FMRFamide-like immunoreactivities was studied in the central nervous system of the earthworm, Eisenia fetida. Alternate serial sections were stained with antisera raised against serotonin and FMRFamide, using the peroxidase-antiperoxidase method. The immunostained consecutive sections were compared by light-microscopy and on reconstructed images using NIH Image and Neurolucida programs. Although there was a large number of serotonin and FMRFamide-like immunoreactive neurons in the central nervous system of Eisenia, co-localization of immunostaining was relatively rare. In the cerebral ganglion no cells were found that stained for both antisera. In the subesophageal and ventral cord ganglia the neurons reacting for both antisera represented approximately 17-23% and 10-14% of the serotonin- and 7-11% and 9-17% of the FMRF-amide-like immunoreactive cells, respectively. It is suggested, that FMRFamide-related peptides act as neuromodulators and may also influence the activity of serotonergic neurons.

Gastrin- and cholecystokinin-like immunoreactivities in the nervous system of the earthworm.

The distribution of cholecystokinin and gastrin-like immunoreactive cell bodies and fibers in the nervous system of 2 annelid worms, Lumbricus terrestris and Eisenia fetida, has been studied by means of immunohistochemistry. The cerebral ganglion contains 170-250, the subesophageal ganglion contains 120-150, and the ventral ganglia contain 50-75 cholecystokinin immunoreactive cells, that represent 8-12%, 8-10% and 4-5% of the total cell number, respectively. The anti-gastrin serum stained 330-360 nerve cells in the cerebral, 32-46 in the subesophageal and 7-25 in the ventral cord ganglia, representing 15-16%, 2-3% and 0.5-2% of the total cell number. Immunopositivity was found with both antisera in the enteric nervous system, where the stomatogastric ganglia and the enteric plexus contain immunoreactive cells and fibers. Immunopositive cells were found in the epithelial and subepithelial cells, as well as in nerve cells innervating the muscular layer of the gastrointestinal tube. Various epidermal sensory cells also displayed strong immunoreactivity. According to our findings and the results of several functional studies, it is suggested that in annelids cholecystokinin- and gastrin-like peptides may be involved in digestive regulation, sensory processes and central integrating processes.

Comparative distribution of urocortin- and CRF-like immunoreactivities in the nervous system of the earthworm Lumbricus terrestris

Corticotropin-releasing factor (CRF) and urocortin (Ucn) are both members of the CRF neuropeptide family. The distribution of Ucn- and CRF-like immunoreactive (ir) structures in the central nervous system of several vertebrate species has been studied, but little is known about that in non-vertebrates. We used a highly specific polyclonal antibody against rat Ucn and CRF to determine and compare the distribution of Ucn- and CRF-like immunoreactivity in the earthworm nervous system. Several Ucn- and CRF-like ir perikarya were described in the cerebral ganglion, subesophageal and ventral cord ganglia. The majority of Ucn-like ir cells were found in the ventral ganglia, whereas CRF-like ir cells were most abundant in the cerebral ganglion. Scattered Ucn- and CRF-like ir varicose fiber terminals were seen in all areas of the earthworm central nervous system. Ucn-like ir cell bodies and fiber terminals were also demonstrated in the pharyngeal wall. No co-localization of Ucn- and CRF-like ir nervous structures were observed. This study provided morphological evidence that Ucn- and CRF-like neurosecretory products exist in the earthworm central nervous system. Furthermore, both the distribution and morphology of Ucn- and CRF-like ir structures were distinct, therefore, it can be hypothesized that these neuropeptides exert different neurendocrine functions in the earthworm nervous system.