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PubMed1994

The FMRFamide-like neuropeptide AF2 (Ascaris suum) is present in the free-living nematode, Panagrellus redivivus (Nematoda, Rhabditida).

Available primary structural information suggests that the FMRFamide-related peptides (FaRPs) from parasitic and free-living nematodes are different, and that free-living forms may not represent appropriate models for the study of the neurochemistry of parasitic forms in the laboratory. However, here we report the isolation and unequivocal identification of AF2 (originally isolated from the parasite, Ascaris suum) from acidified alcoholic extracts of the free-living species, Panagrellus redivivus. While reverse-phase HPLC analysis of extracts revealed FMRFamide-immunoreactivity to be highly heterogeneous, AF2 was the predominant FMRFamide-immunoreactive peptide present (at least 26 pmol/g wet weight of worms). This peptide was also the major immunoreactant identified by an antiserum raised to the conserved C-terminal hexapeptide amide of mammalian pancreatic polypeptide (PP), which has been used previously to isolate neuropeptide F (NPF). These observations were confirmed by radioimmunoassay and chromatographic fractionation of an acidified alcoholic extract of A. suum heads. The FMRFamide-related peptides present in a nematode extract may be highly dependent on the extraction medium employed, and these data would suggest that this complement of neuropeptides may not be as different between parasitic and free-living nematodes as initial studies have suggested. Finally, all of the evidence suggests that NPF is not present in nematodes and that the PP-immunoreactant previously demonstrated immunochemically is probably AF2.

Amino Acid Sequence↗
PubMed1992

A FMRFamide-like peptide is associated with the myotropic ovulation hormone in Rhodnius prolixus.

The protocerebral neurosecretory cells previously shown to be the source of the myotropin controlling ovulation in Rhodnius prolixus react in an immunocytochemical assay using an antiserum against FMRFamide. When the same antiserum was injected into fed mated females at the appropriate time the timing of oviposition was delayed, but the total number of eggs developed was unaffected compared to controls injected with pre-immune rabbit serum. The titer of FMRFamide-like peptide (assayed by RIA) in the hemolymph of mated and virgin females was found to fluctuate with the egg laying cycle, and to reflect earlier determinations of the titer of myotropic activity. Western blots of SDS-PAGE revealed a FMRFamide-immunoreactive peptide of approximately 8.5 kDa in both hemolymph and extracts of the ovulation hormone cells.

Animals↗
PubMed2002

Ontogenetic organization of the FMRFamide immunoreactivity in the nervus terminalis of the lungfish, Neoceratodus forsteri.

The development of the nervus terminalis system in the lungfish, Neoceratodus forsteri, was investigated by using FMRFamide as a marker. FMRFamide immunoreactivity appears first within the brain, in the dorsal hypothalamus at a stage around hatching. At a slightly later stage, immunoreactivity appears in the olfactory mucosa. These immunoreactive cells move outside the olfactory organ to form the ganglion of the nervus terminalis. Immunoreactive processes emerge from the ganglion of the nervus terminalis in two directions, one which joins the olfactory nerve to travel to the brain and the other which courses below the brain to enter at the level of the preoptic nucleus. Neither the ganglion of the nervus terminalis nor the two branches of the nervus terminalis form after surgical removal of the olfactory placode at a stage before the development of FMRFamide immunoreactivity external to the brain. Because this study has confirmed that the nervus terminalis in lungfish comprises both an anterior and a posterior branch, it forms the basis for discussion of homology between these branches and the nervus terminalis of other anamniote vertebrates.

Animals↗
PubMed1987

Distribution and partial characterization of FMRFamide-like peptides in the stomatogastric nervous systems of the rock crab, Cancer borealis, and the spiny lobster, Panulirus interruptus.

The distribution of FMRFamide-like peptides was studied in the complete stomatogastric nervous system [the paired commissural ganglia, single oesophageal ganglion, and the single stomatogastric ganglion (STG)] of two decapod crustacean species, the spiny lobster Panulirus interruptus and the rock crab Cancer borealis, by using immunocytochemical techniques. Antiserum 231 from the O'Donohue laboratory and antiserum 671C (described here) gave essentially the same staining patterns. In the commissural ganglia of both species there were ten to 20 stained neurons and dense neuropilar staining. The oesophageal ganglion of the crab had four stained neurons. Lucifer Yellow backfills followed by immunostaining showed that the two larger stained neurons of the oesophageal ganglion sent processes into the inferior ventricular nerve. The two smaller neurons sent processes into the inferior oesophageal nerves. The oesophageal ganglion of the lobster had two stained neurons that sent processes into the inferior ventricular nerve as well. None of the somata of the STG stained in either species, but in both species stained fibers were seen in the stomatogastric nerve that entered the STGs and ramified profusely throughout the neuropil. In some preparations of the crab, a stained fiber was visible in the dorsal ventricular nerve. The amounts of the FMRFamide-like peptides found in all regions of the nervous system of P. interruptus and C. borealis were determined by radioimmune assay (RIA). Column chromatography and high-performance liquid chromatography suggest that, in both species, much if not all of the RIA-assayable material is accountable for by peptides that are larger and more hydrophobic than FMRFamide.

Animals↗
PubMed1991

Distribution of FMRFamide-related peptides in the blood-feeding bug, Rhodnius prolixus.

Immunohistochemistry was used to study the distribution of FMRFamide-like material in the central and peripheral nervous systems and visceral tissues of 5th instar Rhodnius prolixus. Over 200 immunoreactive cell bodies and their processes as well as extensive neuropile regions were distributed throughout the nervous system. Immunoreactive processes were seen over the cephalic aorta, corpus cardiacum/corpus allatum complex, and in neurohaemal sites on the abdominal nerves. In visceral tissues, immunoreactive processes were seen innervating the salivary glands, the foregut, and the hindgut. Immunoreactive cells were also found in the anterior midgut (i.e., the crop and the anterior intestine). A radioimmunoassay specific for "RFamide" carboxy-terminal peptides was used to quantify the amount and the distribution of FMRFamide-like material. Reversed-phase high performance liquid chromatography of nervous tissue extracts revealed several peaks of immunoreactive material. The results suggest the existence of a number of FMRFamide-related peptides in Rhodnius which may have roles in both central and peripheral transmission, may be released as neurohormones and may have endocrine functions in the gut.

Amino Acid Sequence↗
PubMed1992

Localization of FMRFamide-like peptides in Caenorhabditis elegans.

The neuropeptide FMRFamide (Phe-Met-Arg-Phe-NH2) is a member of a large family of related peptides that have been found throughout the animal kingdom. By using an antiserum specific for the Arg-Phe-NH2 moiety, we have found that about 10% of the neurons in the nematode Caenorhabditis elegans are immunoreactive. Most of these neurons, which include sensory, motor, and interneurons, were identified on the basis of their number, position, and projection pattern and by analysis of characterized mutants. Neurons that were immunoreactive in hermaphrodite animals were generally also found in males, but each sex had, in addition, sex-specific immunoreactive cells. Staining of hermaphrodite animals from different larval stages suggests that the onset of FMRFamide-like expression is differentially regulated among the cells. We have found a possible neuromodulatory role for the related peptide FLRFamide (Phe-Leu-Arg-Phe-NH2). In an egg-laying assay, FLRFamide by itself was not active but could potentiate a serotonin effect. The FMRFamide-like immunoreactivity was also used as a marker to examine the differentiation of cells that normally undergo programmed cell death. Cells that are destined to die in the Pn.a lineages appear to differentiate and adopt the fate of lineally equivalent cells before cell death.

Amino Acid Sequence↗
PubMed1993

An immunocytochemical study of the FMRFamide neuropeptide gene products in Drosophila.

We have mapped protein expression of the FMRFamide neuropeptide gene in Drosophila with polyclonal antisera against three small peptides whose sequences were derived from the Drosophila proFMRFamide precursor. One antiserum was affinity-purified and extensively characterized. The enriched antibodies labeled 15-21 bilaterally symmetric pairs of neurons in a pattern that corresponded very closely to the pattern of in situ hybridization that was determined previously (Schneider et al. [1991] J. Comp. Neurol. 304:608-622; O'Brien et al. [1991] J. Comp. Neurol. 304:623-638). The other antisera produced complementary results. These findings suggest that the antisera specifically label cells that express the FMRFamide gene. In larvae we consistently observed strong staining in identified interneurons and neuroendocrine cells, and moderate to weak staining in neurons of unknown function. The adult pattern of expression included both larval neurons whose immunoreactivity persisted through metamorphosis and adult-specific neurons. During metamorphosis, we observed transient staining in a small number of neurons and in specific neuropil regions that included the central body, the protocerebral bridge, and the optic ganglia. Based on these morphological features, we suggest that the FMRFamide-like neuropeptides in Drosophila play a number of functional roles, perhaps affecting both physiological and developmental phenomena. Such roles include general modulation throughout all post-embryonic stages, via the blood, and also more stage- and region-specific modulation within the CNS.

Amino Acid Sequence↗
PubMed1995

Localisation, quantitation, and characterisation of neuropeptide F- and FMRFamide-immunoreactive peptides in turbellarians and a monogenean: a comparative study.

Over the past decade it has become clear that the nervous systems of platyhelminths are both complex and highly developed, particularly in peptidergic elements. The central position of an ancestral flatworm in the evolution of the Bilateria has placed a greater importance on the study of modern flatworms. Using antisera generated to the C-terminal region of platyhelminth neuropeptide F and the molluscan neuropeptide, FMRFamide, in immunocytochemistry at both light and ultrastructural levels, immunoreactivities have been localised within the nervous systems of three species of triclad turbellarians, Dugesia lugubris, Dendrocoelum lacteum, and Polycelis nigra, and one species of monogenean trematode, Diclidophora merlangi. Extensive immunostaining was obtained with both antisera throughout the central and peripheral nervous systems of all species studied, but intensity and abundance was significantly greater in the turbellarians. Indirect electron-immunogold labeling demonstrated that immunoreactivity to both neuropeptides was often colocalised in neurosecretory vesicles, although discrete populations of vesicles were also observed. Radioimmunoassay of extracts of all species confirmed that neuropeptide F immunoreactivity was consistently more abundant than FMRFamide immunoreactivity, and that the levels of both in the three turbellarians were several orders of magnitude greater than those found in the monogenean. Chromatographic analyses of turbellarian extracts revealed that neuropeptide F and FMRFamide immunoreactivities were attributable to different peptides. These data imply that the neuropeptidergic systems systems of turbellarians are considerably more extensive than those of monogeneans, and would suggest that a regression has occurred in the latter as a consequence of the adoption of a mere sedentary parasitic lifestyle.

Animals↗
PubMed2002

Presence of two neuropeptides in the fusiform ganglion and reproductive ducts of Octopus vulgaris: FMRFamide and gonadotropin-releasing hormone (GnRH).

We have found evidence of FMRFamide-like and cGnRH-I-like immunoreactivity in the central nervous system (CNS) and in the reproductive ducts of both female and male cephalopod Octopus vulgaris. Cell bodies and fibers were immunolocalized in the fusiform ganglion from which the nerves that reach the female and male reproductive ducts arise. FMRFamide-like and cGnRH-I-like immunoreactive nerve endings were present in the oviduct, and in the oviducal gland of the female and in the seminal vesicle of the male. The GnRH-like peptide from the reproductive ducts has been partially characterized by HPLC. The retention time of the Octopus vulgaris GnRH-like peptide was similar to the retention time of cGnRH-I. Based on these observations we suggest that FMRFamide-like and a novel GnRH-like peptide are involved in the control of reproductive ducts of Octopus vulgaris. One possibility is that the peptides affect gamete transport. Another possibility is that they regulate secretory products such as mucus and mucilaginous substances from the oviducal gland and the seminal vesicle. Our data provide further evidence to support the hypothesis of the existence of a central and peripheral peptidergic control of reproduction of Octopus vulgaris.

Animals↗
PubMed1995

GYIRFamide: a novel FMRFamide-related peptide (FaRP) from the triclad turbellarian, Dugesia tigrina.

Modern phylogenetic schemes propose a free-living turbellarian-like organism as the ancestor of all Bilateria, including chordates. While neuropeptides are now known to be of ancient origin within the nervous systems of invertebrates, the neuropeptides of turbellarians remain virtually unexplored. Here we report the primary structure of an FMRFamide-related pentapeptide, Gly-Tyr-Ile-Arg-Phe amide (GYIRFamide), isolated from an acidified ethanolic extract of the aquatic triclad turbellarian, Dugesia tigrina. Previously, we reported the primary structure, RYIRFamide, from the New Zealand terrestrial turbellarian, Artioposthia triangulata, widely regarded as a most atypical species. However, the present data implies a high degree of primary structural conservation between the FMRFamide-related peptides of both species despite the zoogeographical isolation of the New Zealand form for several hundred million years. In addition, while authentic FMRFamide itself has been identified in many molluscs and a few annelids, the current data would suggest that turbellarian analogues are typically pentapeptides with an X-Y-I-R-Famide motif. A protein/peptide database search revealed that the sequence GYIRF is contained within the primary structure of several bacterial Ni/Fe hydrogenase B-type cytochrome subunits and several proliferating cell nuclear antigens (cyclins) from plants.

Amino Acid Sequence↗
PubMed1995

Immunocytochemical mapping of FMRFamide-like peptides in the argasid tick Ornithodoros parkeri and the ixodid tick Dermacentor variabilis.

FMRFamide-like immunoreactivity was studied in the argasid tick Ornithodoros parkeri and the ixodid tick Dermacentor variabilis using immunocytochemistry based on the peroxidase-antiperoxidase method. FMRFamide-like immunoreactive cells are widely distributed in various regions of the tick synganglion including protocerebral, cheliceral, stomodeal, palpal, pedal I-IV, and opisthosomal regions in both species. However, there is one layer of immunoreactive cells located on the dorsal surface of the postoesophageal part of the synganglion that is found only in D. variabilis. Besides the immunoreactivity within the cell body and its axons, the neuropile and the neural lamella (the extracellular sheath of the synganglion) are rich in immunoreactive materials. Some coxal muscles are innervated by the FMRFamide-like immunoreactive processes of the nerve from the pedal ganglion.

Animals↗
PubMed1984

Immunocytochemical localization of neurons in the nervous system of the Colorado potato beetle with antisera against FMRFamide and bovine pancreatic polypeptide.

Particular neurons in the nervous system of the Colorado potato beetle, Leptinotarsa decemlineata, are recognized by antisera against bovine pancreatic polypeptide and FMRFamide. Both antisera react with the same neurons. Solid phase absorptions showed that antiserum against bovine pancreatic polypeptide cross-reacts with FMRFamide, whereas antiserum against FMRFamide cross-reacts with bovine pancreatic polypeptide. Some of the immunoreactive neurons have axons branching extensively within the neuropile, which suggests that the peptide is used as transmitter. In the corpus cardiacum, a neurohaemal organ in insects, numerous immunoreactive axon terminals are present. Here, the peptide material is presumably released as a hormone.

Animals↗
PubMed1988

Immunohistological demonstration of a substance related to neuropeptide Y and FMRFamide in the cephalic and thoracic nervous systems of the locust Locusta migratoria.

A neuropeptide related to the mammalian neuropeptide Y (NPY) is present in various neurosecretory cells (NSC) of the cephalic and thoracic nervous systems of the insect Locusta migratoria. Immunoreactive perikarya are detected in the protocerebrum, tritocerebrum, optic lobes and the suboesophageal and thoracic ganglia. They give rise to many immunoreactive processes that ramify extensively throughout the neuropiles. In the brain, prominent axon bundles tightly surround the tractus I to the corpora cardiaca. This fiber pattern suggests that the NPY-like substance may have a neuromodulator and/or neurotransmitter function. This substance may also have a neurohormonal role, since some immunoreactive tracts penetrate into neurohaemal organs via the nervi corporis cardiaci II and the thoracic median nerves. NCS containing NPY-like neuropeptide also display an FMRFamide-like immunoreactivity (except for the abdominal part of the metathoracic ganglion). NPY or FMRFamide antisera are not inactivated after preabsorption with FMRFamide or NPY, respectively. It might therefore be inferred that in locust NSC these two antisera recognize two distinct antigenic sites belonging either to a large polypeptide, or to two distinct neuropeptides.

Amino Acid Sequence↗
PubMed1988

FMRFamide-like immunoreactivity in the metathoracic ganglion of the locust (Schistocerca gregaria).

The distribution of FMRFamide-like immunoreactivity in the metathoracic ganglion of the locust, Schistocerca gregaria, has been investigated in serial semithin transverse sections with the use of the peroxidase-antiperoxidase (PAP) technique. The topographical distribution of approximately 120 immunopositive neurons was established. Antiserum against bovine pancreatic polypeptide (BPP) stains the same ganglionic cells as FMRFamide-antiserum, yet this staining is largely blocked after preabsorption to FMRFamide. A comparison of these results with those from other studies suggests that there may be more than one type of endogenous RFamide-like peptide.

Animals↗
PubMed1990

The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) can activate a ligand-gated ion channel in Helix neurones.

This report presents evidence that the molluscan neuropeptide FMRFamide can directly activate a ligand-gated ion channel in Helix neurones. Using the patch-clamp technique we have observed unitary currents activated by the application of FMRFamide onto outside-out patches. As for the whole-cell response, Na+ ions are the main charge carriers. We conclude that FMRFamide may act as a fast depolarizing neurotransmitter in the Helix nervous system.

Animals↗
PubMed1991

Immunocytochemical distribution of FMRFamide-like substance in the brain of the cloudy dogfish, Scyliorhinus torazame.

The distribution of the molluscan cardioexcitatory tetrapeptide FMRFamide (Phe-Met-Arg-Phe-NH2) in the brain of the cloudy dogfish, Scyliorhinus torazame, was examined by immunocytochemistry. FMRFamide-like immunoreactivity was demonstrated to occur extensively in various regions of the dogfish brain, except for the corpus cerebelli. Immunoreactive neuronal perikarya were located in the ganglion of the nervus terminalis, the preoptic area, and the hypothalamic periventricular gray matter consisting of the nucleus medius hypothalamicus, the nucleus lateralis tuberis, and the nucleus lobi lateralis. Some of the immunoreactive cells in the hypothalamus were identified as cerebrospinal fluid-contacting neurons. The bulk of the immunostained fibers in the nervus terminalis penetrated into the midventral portion of the telencephalon and ran dorsocaudally toward the basal telencephalon and hypothalamus, showing radial projections or ramifications. The labeled fibers were abundant in the midbasal part of the telencephalon and in the hypothalamus, where some fibers were found in loose networks around the cell bodies of the nucleus septi and hypothalamic periventricular nuclei. The fibers demonstrated in the hypothalamus terminated around the vascular wall of the primary capillary plexus of the median eminence or penetrated deeply into the pars intermedia of the hypophysis. These results suggest that, in the dogfish, an FMRFamide-like substance participates in the regulation of adenohypophysial function. This molecule may have a role as a neurotransmitter and/or neuromodulator in the central nervous system.

Amino Acid Sequence↗
PubMed1992

Colocalization of neuropeptide Y (NPY)-like and FMRFamide-like immunoreactivities in the brain of the Atlantic salmon (Salmo salar).

The colocalization of the peptides neuropeptide Y (NPY) and Phe-Met-Arg-Phe-NH2 (FMRFamide) in the brain of the Atlantic salmon was investigated with double immunofluorescence labeling and peroxidase-antiperoxidase immunocytochemical techniques. Colocalization of NPY-like and FMRF amide-like immunoreactivities was observed in neuronal cell bodies and fibers in four brain regions: in the lateral and commissural nuclei of the area ventralis telencephali, in the nucleus ventromedialis thalami, in the laminar nucleus of the mesencephalic tegmentum, and in a group of small neurons situated among the large catecholaminergic neurons in the isthmal region of the brainstem. All cell bodies in these nuclei were immunoreactive to both NPY and FMRF. We consistently observed larger numbers of FMRF-immunoreactive than NPY-immunoreactive fibers. In the nucleus ventromedialis thalami NPY- and FMRFamide-like immunoreactivities were colocalized in cerebrospinal fluid (CSF)-contacting neurons. NPY-immunoreactive, but not FMRF-immunoreactive, neurons were found in the stratum periventriculare of the optic tectum, and at the ventral border of the nucleus habenularis (adjacent to the nucleus dorsolateralis thalami). Neurons belonging to the nucleus of the nervus terminalis were FMRF-immunoreactive but not NPY-immunoreactive. The differential labeling indicates, as do our cross-absorption experiments, that the NPY and FMRFamide antisera recognize different epitopes. Thus, it is probable that NPY-like and FMRF amide-like substances occur in the same neurons in some brain regions.

Animals↗
PubMed1994

The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) directly gates two ion channels in an identified Helix neurone.

FMRFamide (i.e. Phe-Met-Arg-Phe-NH2) application to the C2 neurone of Helix caused a depolarizing response which consisted of a large, rapidly developing, and rapidly desensitizing inward current, underlain by a smaller, slower inward current which did not desensitize. Both currents were carried through sodium-selective channels which were insensitive to D-tubocurarine, and the to the fast sodium channel blockers tetrodotoxin (TTX) and lignocaine. Only the faster, desensitizing current could be blocked by amiloride. FMRFamide also activated two types of unitary inward currents with slightly differing amplitudes in outside-out patches taken from the C2 neurone, both through sodium-selective ion channels. Only the smaller unitary currents readily desensitized and were susceptible to block by amiloride, and they also activated more rapidly. Unitary currents of both types were recorded in outside-out patches in the absence of freely diffusible intracellular mediators, and were also activated when guanosine 5'-O-(2-thiodiphosphate) (GDP [beta-S]) was included in the recording pipette solution. This supports a tight receptor/channel coupling for both responses, with no involvement of GTP-binding proteins. Further, the very fast rate of activation of the smaller channels, which generally carry the major part of the FMRFamide-induced current, strongly indicates that these channels are ligand gated.

Animals↗