FMRFamide-like immunoreactivity and arylamidase activity in turbellarians and nemerteans--evidence for a novel neurovascular coordinating system in nemerteans

Distribution of neuropeptide FF-like immunoreactive structures in the lamprey central nervous system and its relation to catecholaminergic neuronal structures

The neuropeptide FF (NPFF) is an octapeptide of the RFamide-related peptides (FaRPs) that was primarily isolated from the bovine brain. Its distribution in the CNS has been reported in several mammalian species, as well as in some amphibians. Therefore, in order to gain insight in the evolution on the expression pattern of this neuropeptide in vertebrates, we carried out an immunohistochemical study in the sea lamprey, Petromyzon marinus. The distribution of NPFF-like-immunoreactive (NPFF-ir) structures in the lamprey brain is, in general, comparable to that previously described in other vertebrate species. In lamprey, most of the NPFF-ir cells were found in the hypothalamus, particularly in two large populations, the bed nucleus of the tract of the postoptic commissure and the tuberomammillary area. Numerous NPFF-ir cells were also observed in the rostral rhombencephalon, including a population in the dorsal isthmic gray and the reticular formation. Additional labeled neurons were found inside the preoptic region, the parapineal vesicle, the periventricular mesencephalic tegmentum, the descending trigeminal tract, the nucleus of the solitary tract, as well as in the gray matter of the spinal cord. The NPFF-ir fibers were widely distributed in the brain and the spinal cord, being, in general, more concentrated throughout the basal plate. The presence of NPFF-ir fibers in the lamprey neurohypophysis suggests that the involvement of NPFF-like substances in the hypothalamo-hypophyseal system had emerged early during evolution.

A cytochemical study of the serotoninergic, cholinergic and peptidergic components of the reproductive system in the monogenean parasite, Diclidophora merlangi

The reproductive system of the monogenean gill parasite, Diclidophora merlangi, was examined for the presence of cholinergic, serotoninergic and peptidergic innervation using cytochemical and immunocytochemical techniques. Cholinesterase activity and 5-hydroxytryptamine immunoreactivity (5-HT-IR) were confined to neural elements of the male reproductive system, being evident in the innervation of the cirrus, whereas only 5-HT was present in nerves and somata of the elongate seminal vesicle. Peptidergic innervation was localised to both the male and female reproductive systems of the worm. Within the female reproductive apparatus pancreatic polypeptide, peptide tyrosine tyrosine, neuropeptide Y, substance P, neurokinin A, eledoisin, FMRFamide and gastrin/cholecystokinin immunoreactive fibres and somata were observed in the oviduct, vitelline reservoir and ovovitelline duct. Intense peptide immunoreactivity was identified in fibres in the wall of the ootype and in a surrounding population (greater than 100) of somata that were situated beyond Mehlis' gland cells and all of which were connected to the ootype wall by fine cytoplasmic connectives. The strategic location of this peptidergic cell population infers its involvement in the egg-forming sequence in this platyhelminth parasite.