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PubMed2006

Orcokinin immunoreactivity in the accessory medulla of the cockroach Leucophaea maderae.

The accessory medulla is the master circadian clock in the brain of the cockroach Leucophaea maderae and controls circadian locomotor activity. Previous studies have demonstrated that a variety of neuropeptides are prominent neuromediators in this brain area. Recently, members of the orcokinin family of crustacean neuropeptides have been identified in several insect species and shown to be widely distributed in the brain, including the accessory medulla. To investigate the possible involvement of orcokinins in circadian clock function, we have analyzed the distribution of orcokinin immunostaining in the accessory medulla of L. maderae in detail. The accessory medulla is densely innervated by approximately 30 orcokinin-immunoreactive neurons with cell bodies distributed in five of six established cell groups in the accessory medulla. Immunostaining is particularly prominent in three ventromedian neurons. These neurons have processes in a median layer of the medulla and in the internodular neuropil of the accessory medulla and send axonal fibers via the posterior optic commissure to their contralateral counterparts. Double-labeling experiments have revealed the colocalization of orcokinin immunostaining with immunoreactivity for pigment-dispersing hormone, FMRFamide, Mas-allatotropin, and gamma-aminobutyric acid in two cell groups of the accessory medulla, but not in the ventromedian neurons or in the anterior and posterior optic commissure. Immunostaining in the ventromedian neurons suggests that orcokinin-related peptides play a role in the heterolateral transmission of photic input to the pacemaker and/or in the coupling of the bilateral pacemakers of the cockroach.

Animals↗
PubMed2007

Localization of leucomyosuppressin in the brain and circadian clock of the cockroach Leucophaea maderae.

The myosuppressins (X1DVX2HX3FLRFamide), which reduce the frequency of insect muscle contractions, constitute a subgroup of the FMRFamide-related peptides. In the cockroach Leucophaea maderae, we have examined whether leucomyosuppressin (pQDVDHVFLRFamide) is present in the accessory medulla, viz., the circadian clock, which governs circadian locomotor activity rhythms. Antisera that specifically recognize leucomyosuppressin stain one to three neurons near the accessory medulla. MALDI-TOF mass spectrometry has confirmed the presence of leucomyosuppressin in the isolated accessory medulla. Injections of 1.15 pmol leucomyosuppressin into the vicinity of the accessory medulla at various circadian times have revealed no statistically significant effects on the phase of circadian locomotor activity rhythms. This is consistent with the morphology of the myosuppressin-immunoreactive neurons, which restrict their arborizations to the circadian clock and other optic lobe neuropils. Thus, leucomyosuppressin might play a role in the circadian system other than in the control of locomotor activity rhythms.

Animals↗
PubMed1997

Neuronal and nonneuronal taurine-like immunoreactivity in the sea pansy, Renilla koellikeri (Cnidaria, Anthozoa).

A quantitative evaluation of putative amino acid neurotransmitters in sea pansy polyps by high-performance liquid chromatography indicates that the taurine content exceeds that of other amino acids by a 100-fold. The cellular source of this taurine was investigated by immunohistochemistry with two polyclonal antisera raised in rabbit, one against a glutaraldehyde-polylysine-taurine conjugate and the other against a succinylated ovalbumin-carbodiimide-taurine conjugate. Taurine-immunoreactive neurons were localized in a perioral subectodermal nerve net and in the zooid nerve net of the endodermal retractor muscle of the polyp mesenteries. Double labeling experiments revealed that taurine immunostaining does not colocalize with Phe-Mat-Ang-Phe -NH2 FMRFamide immunoreactivity. In addition, strong taurine immunoreactivity was found in nematocytes and other ectodermal cells, in myoepithelial cell bodies of the endoderm, and in calcareous spicule-producing cells of the colonial tissue mass. The limited distribution of neuronal taurine immunostaining to nerve nets associated with muscle systems subtending autozooid polyp retraction supports a role for taurine as a neuromuscular transmitter for this protective reflex. In contrast, the widespread distribution of taurine immunoreactivity in nematocytes and in other nonneuronal cells points to additional cellular functions of taurine, one of which may be to mediate responses to osmotic or metabolic stress.

Animals↗
PubMed1992

cDNA cloning and sequence determination of the pheromone biosynthesis activating neuropeptide of the silkworm, Bombyx mori.

We have identified the cDNAs encoding pheromone biosynthesis activating neuropeptide (PBAN) using PCR technique. The nucleotide sequence showed that the PBAN gene encodes, besides PBAN, diapause hormone and three putative amidated peptides. These four peptides share with PBAN the C-terminal pentapeptide amide which is corresponding to the shortest fragment with pheromonotropic activity. The organization of the PBAN gene is characteristic of several short neuropeptides and has some degree of similarity to that of the gene for the insect neuropeptide FMRFamide. Thus, the PBAN gene products construct a family of structurally related peptides and have various biological functions.

Amino Acid Sequence↗
PubMed1987

Survey of neuropeptide-like immunoreactivity in the lamprey spinal cord.

The distribution of neural elements immunoreactive to several peptides with a possible messenger role was studied in the lamprey spinal cord by using an indirect immunofluorescence method. Different patterns of immunoreactive (IR) fibers were detected by antisera raised against cholecystokinin, metorphamide, bombesin, galanin, corticotropin-releasing factor, somatostatin, peptide YY, neurotensin, calcitonin and FMRFamide. Somatostatin-IR cell bodies were located around the central canal. All immunoreactivity could be abolished by preabsorption with the corresponding peptide. The results suggest that the lamprey spinal cord has several fiber systems containing peptides sharing immunogenic properties with mammalian neuropeptides.

Animals↗
PubMed1995

Simultaneous activation of spinal antiopioid system (neuropeptide FF) and pain facilitatory circuitry by stimulation of opioid receptors in rats.

Neuropeptide FF (NPFF) is a mammalian FMRFamide-like octapeptide with antiopioid properties that inhibits morphine-induced analgesia but also produces hyperalgesia. In the present study, a series of three experiments was carried out to investigate the interactions between opioid receptor stimulation and antiopioid systems. First, by using in vitro superfusion system with rat spinal cord slices, we showed that morphine stimulated NPFF release in a dose-dependent manner. The stimulating effect which was observed with morphine concentrations as low as 100 fM reached a maximum at 0.1 nM, then decreased and was ineffective at 10 microM. The morphine-induced release of NPFF was abolished by naloxone (1 microM) but unaltered by tetrodotoxin. Second, by an in vivo approach, we showed that a single heroin administration (2.5 mg/kg, s.c.) elicited in 30 min a drastic drop (38%) in spinal NPFF content. In a third experiment, we evaluated the capacity of naloxone in revealing an antiopioid component associated with opioid receptor stimulation. The administration of naloxone (1 mg/kg, s.c..) 25 min following that of heroin (2.5 mg/kg, s.c.) not only abolished the heroin-induced increase of tail-flick latency, but also lowered it under the basal value by 30%. These results indicate that opioid receptor stimulation activates both pain inhibitory and pain facilitatory systems in which NPFF may play a significant role and that opiate-induced analgesia is always partly masked.

Animals↗
PubMed1989

Segmental specificity and lateral asymmetry in the differentiation of developmentally homologous neurons during leech embryogenesis.

This paper describes the embryonic development of three leech neurons which undergo spatially regulated patterns of differentiation. In leeches, the nervous system arises from an iterated array of embryonic cell lineages, and each neuron is represented by a set of bilaterally symmetric and segmentally repeated homologs. Two of the cells discussed here, the neurons nz4 and mz3, stain with antibodies to the neuropeptides SCP and FMRFamide during the course of their embryonic differentiation, but only a subset of the initially immunoreactive homologs continue to express this immunoreactivity into postembryonic life. Those nz4 cells which retain immunoreactivity are referred to as RAS neurons, and the persistently immunoreactive mz3 cells referred to as CAS neurons. The subset of homologs which show persistent expression is segment specific, such that the mature RAS and CAS neurons occupy different segmental domains. In addition, both neurons display a final pattern of expression which is laterally asymmetric, with only one of the two homologs in each segment maintaining the RAS or CAS phenotype. Asymmetric differentiation can occur in either orientation for any given segment, although there is a very strong tendency for the persistently immunoreactive cells to lie on opposite sides of successive segments. The fate of the transiently immunoreactive homologs is unclear, but labeling with intracellular lineage tracers suggests that there are some mz3 neurons which survive late into postemobryonic life and never express detectable levels of immunoreactivity. Intracellular lineage tracers also allowed us to follow the development of a third neuron, mz4, which does not stain for either peptide. The mz4 neuron is initially paired, but undergoes an asymmetric pattern of cell death which also shows a strong tendency to alternate sides in successive segments. These spatially coordinated patterns of neuronal survival and/or differentiation suggest that cell interactions play a role in determining the developmental choices made by individual neurons, and a subsequent paper will characterize those interactions through experimental manipulation.

Animals↗
PubMed1992

Analogues of F8Famide resistant to degradation, with high affinity and in vivo effects.

Four analogues of Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2, a mammalian FMRFamide-like peptide with antiopiate properties, were synthesized with N-terminus modifications and were shown to have high affinity for F8Famide binding sites. The degradation rate of these analogues in mouse brain slices was 3 times lower than that of the natural peptide. One analogue, (2DME)Y8Fa (D.Tyr-D.Leu-[N-Me]Phe-Gln-Pro-Gln-Arg-Phe-NH2), produced a clear hyperalgic effect and inhibited morphine analgesia in the mouse tail-flick test at lower doses than did the parent compound. (3D)Y8Fa (D.Tyr-D.Leu-D.Phe-Gln-Pro-Gln-Arg-Phe-NH2) and (2D)Y8Fa (D.Tyr-D.Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) in contrast did not decrease morphine analgesia but were analgesic alone. The analgesic effects of 22 nmol (2D)Y8Fa and (3D)Y8Fa were decreased by (1DME)Y8Fa (D.Tyr-Leu-[N-Me]Phe-Gln-Pro-Gln-Arg-Phe-NH2) or (2DME)Y8Fa and were reversed by naloxone. These results indicate opioid modulating properties of F8Famide. These analogues may prove to be useful tools for studying the modulation of pain by F8Famide.

Amino Acid Sequence↗
PubMed1996

A new method for double immunolabelling with primary antibodies from identical species.

There are several double immunolabelling methods but each has its drawbacks. More often than not, antibodies with the required specificities are available in only one species and their use normally produces false labels due to cross-reactivity. We describe a new and reliable technique for staining with primary antibodies from the same species, that can even be employed on tissues of the donor species. The protocol avoids cross-reactivities without loss in sensitivity, uses commercially available reagents and takes advantage of enzymatic detection, although it can be adapted for fluorescent labelling. Briefly, tissue is incubated with one primary antibody, followed by a peroxidase-coupled secondary antibody which is detected using amino ethyl carbazol to give a red reaction product. Meanwhile, the next primary antibody is coupled in vitro to a biotinylated secondary antibody and excess binding sites quenched with normal immune serum from the same species as the primary antibody. This complex is applied to tissue and detected by the avidin-biotin/alkaline phosphatase technique using naphthol-AS-MX-phosphate/Fast Blue BB to produce a blue label. In addition to extensive controls, the reliability and broad applicability of this method has been confirmed in (1) murine skin cryostat sections to co-visualize antigen-presenting cells (MHC class II-immunoreactive; "-ir') with either antigen detecting T lymphocytes (CD4-ir) or Langerhans cells (NLDC-145-ir) and (2) locust (Insecta) abdominal ganglion paraffin sections, where it is known that immunoreactivities for octopamine and a FMRFamide-related peptide are colocalized in only one, uniquely identifiable neuron.

Animals↗
PubMed1994

Characterization of a potent agonist for NPFF receptors: binding study on rat spinal cord membranes.

Specific receptors for the octapeptide FLFQPQRFamide (NPFF), a mammalian FMRFamide-like neuropeptide with anti-opiate properties have been identified in rat central nervous system. However, exploration of the biological role of this peptide requires a peptidase-resistant agonist. In this study, the stability and binding characteristics of [125I]DYLMeFQPQRFamide, a radioiodinated analogue of NPFF, on rat spinal cord tissue were determined and compared with those of [125I]YLFQPQRFamide, the reference ligand which previously permitted to characterize NPFF binding sites. In a binding assay, [125I]DYLMeFQPQRFamide remained intact in the presence of membranes without peptidase inhibitors, whereas [125I]YLFQPQRFamide was completely hydrolysed. The specific binding was time-dependent, dose-dependent, saturable and reversible. [125I]DYLMeFQPQRFamide shared the same binding characteristics as [125I]YLFQPQRFamide (Kd = 0.07 nM; Bmax = 14.7 fmol/mg protein). Binding was not affected by various spinal cord opioids or peptides. Autoradiographic studies indicated that binding sites were mainly located in the most external layers of dorsal horn where high densities of NPFF binding sites have previously been described. [125I]YLFQPQRFamide and [125I]DYLMeFQPQRFamide binding sites were both GTP-regulated. These findings indicate that DYLMeFQPQRFamide should be of value in studies on NPFF-mediated actions in vivo.

Amino Acid Sequence↗
PubMed1987

Proenkephalin-A derived peptides do not modulate cardiovascular effects of epinephrine on the isolated rat atrial preparations.

The catecholamines and the opioid peptides are found to be co-localized in the adrenomedullary chromaffin cells. They are co-secreted from the chromaffin granules in response to various stimuli. The stress-induced released of epinephrine is known to exert its effect on the cardiovascular system resulting in the changes in heart rate and blood pressure. However, the role of the co-released proenkephalin-A derived peptides has not been extensively characterized. Previous work from several investigators suggested that the peptides modulate cardiac functions of the catecholamines. There is considerable conflicting results among these reports. Results from the isolated rat atrial preparation indicated that enkephalins attenuated the increase in atrial rate induced by norepinephrine through restriction of the calcium fluxes. Nonetheless, others reported insensitivity of the enkephalins in similar or different test systems. We further re-examined these discrepancies using the isolated rat atrial preparation to investigate the opioid peptide modulatory effect on the cardiovascular changes induced by exogenous epinephrine. Alterations in rate and force of contraction resulting from epinephrine and the peptides were both studied in parallel. The opioid peptides used in this study were [Met5]-enkephalin (ME), [Leu5]-enkephalin (LE), FMRFamide, [Met5]-enkephalyl-Arg6-Phe7 (MEAP), peptide E, and the non-selective opioid agonist, etorphine. We report here that none of the opioid peptides were effective in alleviating or attenuating the increase in heart rate and developed tension caused by epinephrine. The peptides did not affect the basal beating rate nor the force of contraction. Thus, the present results clearly demonstrate the insensitivity of the enkephalins in modulating the cardiac effects of epinephrine. They further indirectly support the prejunctional synaptic nerve endings as the potential peripheral site of action of the peptides.

Animals↗
PubMed1990

Differential interactions of cholecystokinin and FLFQPQRF-NH2 with mu and delta opioid antinociception in the rat spinal cord.

An in vivo preparation of the rat spinal cord was used to investigate the electrophysiological actions of two non-opioid peptides, cholecystokinin (CCK8) and FLFQPQRF-NH2 (FMRFamide-like peptide) applied intrathecally. These compounds were examined alone and as a pretreatment before DAGO, a mu opioid agonist, and DSTBULET, a delta opioid agonist, both which selectively reduce C-fibre evoked dorsal horn neurone activity elicited by transcutaneous electrical stimulation. Given alone, CCK8 (1 microgram) elicited a modest enhancement of C-fibre induced activity which returned to control levels after 20 min, while FLFQPQRF-NH2 (10 micrograms) had no significant effect on C-fibre evoked firing. As a pretreatment, however, both peptides selectively prevented the inhibition of C-fibre evoked activity normally resulting from intrathecal DAGO, while having no effect on that resulting from DSTBULET. Further, CCK8 enhanced the facilitation of C-fibre evoked firing normally observed with low doses of DAGO. These data indicate that the anti-opioid roles suggested for CCK8 and FLFQPQRF-NH2 may be specific for neural elements utilizing the mu opioid receptor.

Animals↗
PubMed1995

Binding and activation regions of the decapeptide PDVDHVFLRFamide (SchistoFLRFamide).

In the oviduct of Locusta migratoria, a FMRFamide-related peptide, PDVDHVFLRFamide (SchistoFLRFamide) acts as a neuromodulator, inhibiting spontaneous and induced muscle contraction. In this study, we have used N-terminal truncated peptides to show that PDVDHVFLRFamide has separated binding and activation regions. VFLRFamide is the minimum sequence required for binding, whereas HVFLRFamide is the minimum sequence for inhibitory biological activity. Thus the His residue, which does not contribute to binding, is a critical amino acid for the activation of the receptor. The N-terminal PDVD appears to play little or no role in either binding or activation. VFLRFamide, which binds to the receptor but yields no inhibitory biological activity, is a strong antagonist of PDVDHVFLRFamide.

Amino Acid Sequence↗
PubMedDate not supplied

Brain neuropeptides: actions on central cardiovascular control mechanisms.

The many peptides we have not considered (e.g. gastrin, motilin, FMRFamide, carnosine, litorin, dermorphin, casomorphin, eledoisin, prolactin, growth hormone, neuromedin U, proctolin, etc.) were omitted due to lack of information as far as any putative central cardiovascular effects are concerned. However, even for some of these peptide pariahs intriguing snippets of information are available now (e.g. ref. 85), although as we write, the list of possible candidates for investigation grows longer. On an optimistic note, it is becoming clear that many brain neuropeptides may have important effects on cardiovascular regulation. It seems feasible that 'chemically coded' pathways in the brain might be the neuroanatomical correlate of a 'viscerotopic' organization of cardiovascular control mechanisms, whereby the activity of the heart and flows through vascular beds are individually controlled, but in an integrated fashion, utilizing particular combinations of neurotransmitters and neuropeptides within the brain. Such possibilities can only be investigated, properly, by measurement of changes in cardiac output and regional haemodynamics in response to appropriate interventions, in conscious, unrestrained animals.

Animals↗
PubMed1991

Ultrastructural localization of neuropeptide FF, a new neuropeptide in the brain and pituitary of rats.

The octapeptide FLFQPQRF-NH2 or neuropeptide FF ('F8Famide'; FMRFamide-like peptide'; 'morphine-modulating peptide') has been isolated from the bovine brain. In this study, the ultrastructural localization of neuropeptide FF-like immunoreactivity was examined with pre-embedding immuno-electron microscopy in the nucleus of the solitary tract and in the posterior lobe of the pituitary gland of an adult rat. Neuropeptide FF-like immunoreactivity was detected only in neuronal structures of the medial and commissural nuclei of the solitary tract and in the neurohypophysis. In the medulla, the peroxidase-antiperoxidase reaction product was localized in large (100 nm) dense-cored vesicles and in the cytoplasm of the neuronal perikarya, dendrites and axon terminals. In the labeled terminals, small (50 nm) clear vesicles rimmed with the peroxidase-antiperoxidase reaction product were seen. Synaptic contacts of labeled perikarya and dendrites with unlabeled axon terminals were observed. Labeled axon terminals formed contacts with unlabeled dendrites and perikarya. In the posterior lobe of the pituitary gland, neuropeptide FF-like immunoreactivity was localized in nerve terminals frequently associated with blood vessels. The results suggest that neuropeptide FF-like peptides are localized exclusively in neuronal structures and that they are synthesized in cell somata and released from axon terminals. In the brain, neuropeptide FF-like peptides may act as neuromodulators involved in the regulation of autonomic functions. The localization of neuropeptide FF-like immunoreactivity in the neurohypophysis suggests endocrine regulatory functions of these peptides.

Amino Acid Sequence↗
PubMed1996

Characterization of the RFamide-like neuropeptides in the nervus terminalis of the goldfish (Carassius auratus).

FMRFamide-immunoreactivity has been demonstrated in the CNS of many vertebrate species. We sought to further characterize this immunoreactivity in nervus terminalis retinal efferents of the goldfish using an antiserum raised against a bovine morphine modulating peptide (A18Famide). This antiserum robustly labels nervus terminalis efferents to the retina, as well as a sub-population of retinal amacrine cells. Under immunocytochemical conditions the antiserum cross-reacted with neuropeptide Y-like as well as A18Famide-like peptides, but under conditions of radioimmunoassay it was highly specific for A18Famide-like peptides. High pressure liquid chromatography, gel permeation chromatography and radioimmunoassay showed that at least two different RFamide-like peptides, approximately the same size as the bovine RFamide-like peptides, are present in the goldfish nervus terminalis.

Animals↗
PubMedDate not supplied

AF2, an Ascaris neuropeptide: isolation, sequence, and bioactivity.

A FMRFamide-like neuropeptide, KHEYLRFamide (Lys-His-Glu-Tyr-Leu-Arg-Phe-amide; AF2) was isolated from a head extract of the nematode Ascaris suum by using a three-step HPLC separation. In a dorsal muscle strip preparation, synthetic AF2 produced multiple effects on muscle tension: a slow relaxation was followed by contraction and rhythmic activity. Sulfated AF2 was no more potent than AF2. The effects on muscle tension were correlated with electrical activity recorded intracellularly from muscle cells. AF2 markedly increased the tension change associated with change in muscle membrane potential.

Action Potentials↗
PubMedDate not supplied

The effect of proctolin analogues and other peptides on locust oviduct muscle contractions.

The locust oviduct bioassay system was used to assess the ability of a variety of peptides to induce oviductal contractions. Proctolin analogues were three orders of magnitude less potent than proctolin. Proctolin supra-analogue and Arg-Tyr-Leu-Ala-Thr demonstrated high activity. Perhaps the most significant finding was the discrepancy between the high binding capacity of the proctolin analogue Arg-Tyr-Ser-Pro-Thr and its relatively low myotropic activity. This observation argues for a crucial role for the leucine residue in activating the proctolin receptor. Several other myotropic peptides were tested for their effect on oviduct contractions. FMRFamide caused contractions at doses several orders of magnitude higher than proctolin. The FLRFamide leucomyosuppression inhibited proctolin-induced contractions. In addition, myomodulin and catch relaxing peptide caused oviductal contractions at low concentrations. The enkephalins had no effect when applied alone but potentiated proctolin-induced oviduct contractions. The mechanism of the potentiation is not known. The data argue for the presence of several binding sites on the oviduct membrane.

Amino Acid Sequence↗