Neuropeptide signaling near and far: how localized and timed is the action of neuropeptides in brain circuits?

Neuropeptide signaling is functionally very diverse and one and the same neuropeptide may act as a circulating neurohormone, as a locally released neuromodulator or even as a cotransmitter of classical fast-acting neurotransmitters. Thus, neuropeptides are produced by a huge variety of neuron types in different parts of the nervous system. Within the central nervous system (CNS) there are numerous types of peptidergic interneurons, some with strictly localized and patterned branching morphologies, others with widespread and diffuse arborizations. From morphology alone it is often difficult to predict the sphere of influence of a peptidergic interneuron, especially since it has been shown that neuropeptides can diffuse over tens of micrometers within neuropils, and that peptides probably are released exclusively in perisynaptic (or non-synaptic) regions. This review addresses some questions related to peptidergic signaling in the insect CNS. How diverse are the spatial relations between peptidergic neurons and their target neurons and what determines the sphere of functional influence? At one extreme there is volume transmission and at the other targeted cotransmission at synapses. Also temporal aspects of peptidergic signaling are of interest: how transient are peptidergic messages? Factors important for these spatial and temporal aspects of peptidergic signaling are proximity between release sites and cognate receptors, distribution of peptidase activity that can terminate peptide action and colocalization of other neuroactive compounds in the presynaptic peptidergic neuron (and corresponding receptors in target neurons). Other factors such as expression of different channel types, receptor inactivation mechanisms and second messenger systems probably also contribute to the diversity in temporal properties of peptide signaling.     

Cholinergic, serotoninergic and peptidergic components of the nervous system of Discocotyle sagittata (Monogenea: Polyopisthocotylea)

Cholinergic, serotoninergic (5-HT) and peptidergic neuronal pathways have been demonstrated in both central and peripheral nervous systems of adult Discocotyle sagittata, using enzyme histochemistry and indirect immunocytochemistry in conjunction with confocal scanning laser microscopy. Antisera to 2 native flatworm neuropeptides, neuropeptide F and the FMRFamide-related peptide (FaRP), GNFFRFamide, were employed to detect peptide immunoreactivity. The CNS is composed of paired cerebral ganglia and connecting dorsal commissure, together with several paired longitudinal nerve cords. The main longitudinal nerve cords (Iateral, ventral and dorsal) are interconnected at intervals by a series of annular cross-connectives, producing a ladder-like arrangement typical of the platyhelminth nervous system. At the level of the haptor, the ventral cords provide nerve roots which innervate each of the 8 clamps. Cholinergic and peptidergic neuronal organisation was similar, but distinct from that of the serotoninergic components. The PNS and reproductive system are predominantly innervated by peptidergic neurones.     

Peptidergic innervation of leg muscles of the cockroach,Periplaneta americana (L.), and a possible role in modulation of muscle contraction

FMRFamide-related peptides of insects are particularly important because of their possible function as neurohormones and neuromodulators on a wide variety of tissues. Part of this study was an investigation of the immunofluorescent staining of motor nerves which arise in the metathoracic ganglion, examined in wholemount using an antiserum that recognizes extended -RFamide peptides (generally recognized to be of the FMRFamide family). This antiserum revealed immunochemical staining of numerous cell bodies in the metathoracic ganglion and of axons in peripheral nerve 5, a large nerve which contains both motor and sensory fibres. Axons staining positive for FMRFamide-related peptides were traced in nerve 5 as far as the femur-tibia joint, and into the first (sensory-motor) and third (motor only) ramus of nerve 5. Reverse-phase HPLC with radioimmunoassay revealed a peak of FMRFamide-related peptide activity in nerve 5 that was coincident with a peak found when thoracic ganglia were processed in the same fashion. A physiological assay was devised to test the ability of various non-native peptides to alter the characteristics of contraction of skeletal muscles of the legs. Using neurally evoked contractions of coxal depressor muscles of the metathoracic leg it was determined that several non-native peptides could potentiate muscle contractions.The results of this study suggest that muscles of the legs receive innervation by identifiable, FMRFamide-related peptide-containing neurons and that the release of peptide(s) at the muscle may be yet another method of modulating the mechanics of muscle contraction.Abbreviations D _f fast depressor motor neuron - D _s slow depressor motor neuron - DU M dorsal unpaired median - FaRPs FMRFamide related peptides - FEFe fast extensor of the femur - FFFe fast flexor of the femur - FITC fluorescein isothiocyanate - FPC fast promotor of the coxa - FPT fast flexor of the pretarsus - I _1–3 inhibitory motor neurons - LMS leucomyosuppressin, N5 nerve 5 - N5r1 first ramus of nerve 5 - PBS phosphate buffered saline - PLCl posterior lateral cluster - RIA radioimmunoassay - SETi slow extensor of the tibia - SFTi slow flexor of the tibia - TFA trifluoroacetic acid - VMCl ventral median cluster     

A novel wide-field neuron with branches in the lamina of the <Emphasis Type="Italic">Drosophila</Emphasis> visual system expresses myoinhibitory peptide and may be associated with the clock

Although neuropeptides are widespread throughout the central nervous system of the fruifly Drosophila, no records exist of peptidergic neurons in the first synaptic region of the visual system, the lamina. Here, we describe a novel type of neuron that has wide-field tangential arborizations just distal to the lamina neuropil and that expresses myoinhibitory peptide (MIP). The cell bodies of these neurons, designated lateral MIP-immunoreactive optic lobe (LMIo) neurons, lie anteriorly at the base of the medulla of the optic lobe. The LMIo neurons also arborize in several layers of the medulla and in the dorso-lateral and lateral protocerebrum. Since the LMIo resemble LN_v clock neurons, we have investigated the relationships between these two sets of neurons by combining MIP-immunolabeling with markers for two of the clock genes, viz., Cryptochrome and Timeless, or with antisera to two peptides expressed in clock neurons, viz., pigment-dispersing factor and ion transport peptide. LMIo neurons do not co-express any of these clock neuron markers. However, branches of LMIo and clock neurons overlap in several regions. Furthermore, the varicose lamina branches of LMIo neurons superimpose those of two large bilateral serotonergic neurons. The close apposition of the terminations of MIP- and serotonin-producing neurons distal to the lamina suggests that they have the same peripheral targets. Our data indicate that the LMIo neurons are not bona fide clock neurons, but they may be associated with the clock system and regulate signaling peripherally in the visual system.     

The nervous system of Microstomum lineare (Turbellaria,Macrostomida)

Summary The nervous system (NS) of Microstomum lineare (Turbellaria, Macrostomida) was studied by electron and light microscopy, combined with fluorescence histochemistry (Falck-Hillarp method for biogenic monoamines). The NS is primitively organized, with a bilobed brain, two lateral nerve cords lacking commissures, and peripheral nerve cells scattered along the nerve cords. The stomatogastric NS, with a pharyngeal nerve ring, is joined to the central NS by a pair of connective ganglia. A green fluorescence in all parts of the NS indicates catecholaminergic neurons as the dominant neuron type.Ultrastructurally, two types of neurons were identified on the basis of their vesicle content: 1. Aminergic (catecholaminergic) neurons containing densecore vesicles of varying electron-density and size, i.e., small dense-core vesicles (diameter 50–100 nm), vesicles with a highly electron-dense core (60–140 nm), and vesicles with an eccentric dense-core. 2. Presumed peptidergic neuro-secretory neurons containing large granular vesicles (diameter about 200 nm) in the stomatogastric NS and peripheral parts of the central NS. In light microscopy, paraldehyde-thionin stained neurons were observed in the same areas.     

Mass spectrometric analysis of single identified neurons of an insect

The combination of retrograde labelling with dextran-tetramethylrhodamine and MALDI-TOF mass spectrometry was used to analyse for the first time the peptidome of a series of morphologically identified single neurosecretory cells of an insect. Eight postero-lateral cells of the metathoracic ganglion of the American cockroach, Periplaneta americana, were used to demonstrate that: (1) the complete dissection procedure can be documented and (2) the mass spectrometric analysis of the dissected somata results in highly reproducible mass spectra. In total, 21 FMRFamide-related peptides were detected in each of the postero-lateral cells which release their neurosecretions via thoracic perisympathetic organs. Direct analysis of these neurohemal organs confirmed the co-storage of FMRFamide-related peptides. Two additional abundant peptides from thoracic perisympathetic organs which were not detectable in the postero-lateral cells were characterized using ESI-Q-TOF MS/MS. De novo sequencing yielded two related peptides (FERL/IEamides) without any similarity with known peptide families of insects.     

Mass spectrometric analysis of FMRFamide-like immunoreactive neurons in the prothoracic and subesophageal ganglion of Periplaneta americana

MALDI-TOF mass spectrometry combined with immunocytochemistry and retrograde labeling, was used to study the expression pattern and morphology of Pea-FMRFamide-related peptides in single neurons of the prothoracic ganglion and the subesophageal ganglion (SEG) of the American cockroach Periplaneta americana. In contrast to the postero-lateral cells (PLCs) of the meta- and mesothoracic ganglion, the prothoracic FMRFamide-related peptides expressing neurons not only extend in the posterior median nerve but also in an anterior median nerve, which is described herein. The peptidome of the prothoracic PLCs is identical with that of the meso- and metathoracic neurons, respectively. In this study, we identified a truncated form of Pea-FMRFa-24 which was found to be more abundant than the peptide originally designated as Pea-FMRF-24. FMRFamide-related peptides expressing postero-lateral cells were also detected in the labial neuromere of the SEG. Although their projection could not be solved, mass spectrometric analyses revealed the same peptide complement in these neurons as found in the thoracic postero-lateral cells. In all neurons which we studied no co-localized peptides of other peptide families were observed.     

Distribution of neuropeptides in the primary olfactory center of the heliothine moth <Emphasis Type="Italic">Heliothis virescens</Emphasis>

Neuropeptides are a diverse widespread class of signaling substances in the nervous system. As a basis for the analysis of peptidergic neurotransmission in the insect olfactory system, we have studied the distribution of neuropeptides in the antennal lobe of the moth Heliothis virescens. Immunocytochemical experiments with antisera recognizing A-type allatostatins (AST-As), Manduca sexta allatotropin (Mas-AT), FMRFamide-related peptides (FaRPs), and tachykinin-related peptides (TKRPs) have shown that members of all four peptide families are present in local interneurons of the antennal lobe. Whereas antisera against AST-As, Mas-AT, and FaRPs give similar staining patterns characterized by dense meshworks of processes confined to the core of all antennal-lobe glomeruli, TKRPs are present only in neurons with blebby processes distributed throughout each glomerulus. In addition to local neurons, a pair of centrifugal neurons with cell bodies in the lateral subesophageal ganglion, arborizations in the antennal lobe, and projections in the inner antenno-cerebral tracts exhibits tachykinin immunostaining. Double-label immunofluorescence has detected the co-localization of AST-As, Mas-AT, and FaRPs in certain local interneurons, whereas TKRPs occurs in a distinct population. MALDI-TOF mass spectrometry has revealed nearly 50 mass peaks in the antennal lobe. Seven of these masses (four AST-As, two N-terminally extended FLRFamides, and Mas-AT) match known moth neuropeptides. The data thus show that local interneurons of the moth antennal lobe are highly differentiated with respect to their neuropeptide content. The antennal lobe therefore represents an ideal preparation for the future analysis of peptide signaling in insect brain.     

Peptidylglycine alpha-amidating monooxygenase (PAM) in Schwann cells and glia as well as neurons

We raised an antiserum against the synthetic peptide FKETTRSFSNECLGTTR corresponding to the amino terminus of the enzyme peptidylglycine alpha-amidating monooxygenase (PAM). Control experiments were performed to determine the specificity of the antiserum and its suitability for the immunohistochemical identification of PAM-containing cells. An immunoaffinity column made with the antibody coupled to Sepharose permitted the isolation of the active enzyme. Peptide-agarose immunoadsorbant removed the antibodies responsible for the characteristic staining patterns in immunohistochemical experiments. As expected from the widespread distribution of amidated peptides in the nervous system, PAM immunoreactivity was detected in perikarya in a variety of locations, including the pituitary, the hypothalamic periventricular and supraoptic nuclei, neocortex, and sensory ganglia. Punctate immunostained fibers, especially around neuronal perikarya, were observed in regions known to receive amidated peptidergic afferents. In addition, PAM immunoreactivity was observed in some neurons not known to produce amidated peptides (e.g., pyramidal cells of the hippocampus). This result suggests that these neurons also produce an amidated peptide. PAM immunoreactivity was also detected in several unexpected cell types, including ependyma, choroid plexus, oligodendroglia, and Schwann cells. The presence of enzymatically active PAM in Schwann cells was confirmed by measurements of amidating activity in ligated and control sciatic nerve. These results suggest that these non-neuronal cells may produce amidated peptides.     

Structure-activity relationships of 18 endogenous neuropeptides on the motor nervous system of the nematode Ascaris suum

Neuropeptides play an important role in all nervous systems and structure-activity studies of related peptides is one approach to understanding this role. This study of the motor nervous system of the parasitic nematode Ascaris suum describes the physiological effects of a family of 18 endogenous Ascaris FMRFamide-like peptides (AF peptides) on the membrane potential and input resistance of the dorsal excitatory type 2 (DE2) and dorsal inhibitory (DI) motor neurons. These motor neurons are part of the final common output pathway from the motor nervous system to the somatic muscle cells responsible for locomotion. AF peptide effects on the frequency of excitatory postsynaptic potentials (EPSPs) in DE2 motor neurons were also measured to infer peptide effects on central presynaptic spiking neurons. AF peptide injections into intact worms were made to assess their qualitative effects on behavior, providing a context for interpreting motor neuron data. One category of AF peptides, N-terminally extended -FIRFa peptides (AF5, AF7 and AF1), has pronounced behavioral effects and qualitatively similar, but quantitatively different effects on DE2 and DI motor neurons. A second category of AF peptides (AF2, AF9, and AF8) also produces dramatic behavioral effects and strong electrophysiological effects on DE2 and/or DI motor neurons. A third category of AF peptides, consisting of six members of the -PGVLRFa group (which are encoded by the same gene and have closely related sequences) and peptide AF11, have pronounced behavioral effects, but relatively weak or negligible effects on DE2 and DI motor neurons. A fourth category of AF peptides, also consisting of structurally unrelated members, has pronounced behavioral effects and, as individual peptides, similar effects on both DE2 and DI motor neurons; AF15 is excitatory, while AF17 and AF19 are inhibitory, on both motor neuron types. Finally, two AF peptides (AF6, AF16) are relatively weak or inactive in producing behavioral or motor neuronal effects. Based on comparisons of the effects of AF peptides on DE2 and DI motor neurons, a tentative list of 5 major response-types is proposed as a working hypothesis to guide the search for AF peptide receptors. The findings attest to the potential complexity of neurosignaling in this comparatively simple nervous system.     

Interaction of opioid peptides and the dopaminergic system in the myenteric plexus of the guniea pig ileum

The effects of treatment with dopamine agonists and 6-hydroxydopamine on the release of opioid peptides from the myenteric plexus of guinea-pig ileum were examined. Apomorphine or bromocriptine treatment at doses that act on dopamine autoreceptors to inhibit dopamine release resulted in a significant elevation of the release of opioid peptides. 6-hydroxydopamine treatment, which produces a lesion of catecholaminergic nerve terminals also resulted in an increase in opioid peptide release. These findings indicate that interruption of dopaminergic transmission in the myenteric plexus produces an increase in the release of opioid peptides and suggest an inhibitory modulation of opioid peptidergic neurons by dopamine systems in the myenteric plexus of the guinea-pig ileum.     

The median eminence as a model to study presynaptic regulation of neural peptide release

Presynaptic receptors in peptidergic neurons within the brain should be considered as an important target upon which different neurotransmitters or neuromodulators can act to affect peptide release. Evidence reviewed in this paper indicates that the median eminence (ME) of the hypothalamus is an area where many such interactions at the presynaptic level take place. Release of LHRH, somatostatin and vasopressin is affected by a variety of neurotransmitters or neuromodulators, such as norepinephrine, dopamine, epinephrine, histamine, cholinergic and opioid agonists, and peptides such as angiotensin II. The actions of these agents were prevented by the use of specific receptor blockers, indicating the specificity of the response evoked. Furthermore, with the use of classical pharmacological approaches, the type and affinity of the receptor involved is well defined. Other agents, such as prostaglandins (PGE2) or steroids (estradiol) were found to affect the activity of the peptidergic neuron at the synaptic terminal by stimulating directly peptide release (as seems to be the case for the PGE2/LHRH interaction) or by changing the sensitivity of the terminal to other transmitters, as shown for estradiol. In conclusion, the evidence presented indicates that the ME is an excellent model to study presynaptic regulation of neural peptide release. A set of criteria was defined within the text to establish the physiological significance of the in vitro studies. Several of the substances tested, and particularly norepinephrine and dopamine, seem to meet all the requirements to be considered physiological presynaptic regulators of neural peptide release at the level of the ME.     

Effects and consequences of nerve injury on the electrical properties of sensory neurons

Nociceptive pain alerts the body to potential or actual tissue damage. By contrast, neuropathic or "noninflammatory" pain, which results from injury to the nervous system, serves no useful purpose. It typically continues for years after the original injury has healed. Sciatic nerve lesions can invoke chronic neuropathic pain that is accompanied by persistent, spontaneous activity in primary afferent fibers. This activity, which reflects changes in the properties and functional expression of Na+, K+, and Ca2+ channels, initiates a further increase in the excitability of second-order sensory neurons in the dorsal horn. This change persists for many weeks. The source of origin of the pain thus moves from the peripheral to the central nervous system. We hypothesize that this centralization of pain involves the inappropriate release of peptidergic neuromodulators from primary afferent fibers. Peptides such as substance P, neuropeptide Y (NPY), calcitonin-gene-related peptide (CGRP), and brain-derived neurotrophic factor (BDNF) may promote enduring changes in excitability as a consequence of neurotrophic actions on ion channel expression in the dorsal horn. Findings that form the basis of this hypothesis are reviewed. Study of the neurotrophic control of ion channel expression by spinal peptides may thus provide new insights into the etiology of neuropathic pain.     

Isolation, Localization, and Bioactivity of the FMRFamide-Related Neuropeptides GYIRFamide and YIRFamide from the Marine Turbellarian Bdelloura candida

Abstract: Two FMRFamide-related neuropeptides, GYIRFamide and YIRFamide, were isolated from the marine turbellarian Bdelloura candida . The peptides elicited a dose-dependent contraction of isolated turbellarian muscle fibers, and both were more potent than FMRFamide. Structure-activity studies, using a range of analogues of the tetrapeptide amide, indicated that the structure of the endogenous peptides was optimal for peak activity. Immunocytochemistry, using an autologous antiserum, revealed a widespread distribution of peptide immunoreactivity within central and peripheral neurons and their processes. This study indicates an important role for GYIRFamide and YIRFamide in the control of neuromuscular function in turbellarians.     

Peptidergic regulation of gastrointestinal motility in rodents

Peptides involved in the endocrine and enteric nervous systems as well as in the central nervous system exert concerted action on gastrointestinal motility. Mechanical and chemical stimuli which induce peptide release from the epithelial endocrine cells are the earliest step in the initiation of peristaltic activities. Gut peptides exert hormonal effects, but peptide-containing stimulatory (Ach/substance P/tachykinin) and inhibitory (VIP/PACAP/NO) neurons are also involved in the induction of ascending contraction and descending relaxation, respectively. The dorsal vagal complex (DVC), located in the medulla of the brainstem, constitutes the basic neural circuitry of vago-vagal reflex control of gastrointestinal motility. Several gut peptides act on the DVC to modify vagal cholinergic reflexes directly (PYY and PP) or indirectly via afferent fibers in the periphery (CCK and GLP-1). The DVC is also a primary site of action of many neuropeptides (such as TRH and NPY) in mediating gastrointestinal motor activities. The identification over the last few years of a number of neuropeptide systems has greatly changed the field of feeding and body weight regulation. By exploring the brain and gut systems that employ recently identified peptidergic molecules, it will be possible to elaborate on the central and peripheral pathways involved in the regulation of gastrointestinal motility.     

The regulation of food intake by selective stimulation of the type 3 melanocortin receptor (MC3R)

High levels of binding sites for melanocortin peptides exist within the arcuate nucleus, and a functional response to melanocortin peptides has been demonstrated in arcuate POMC neurons. Because the MC3R is thought to function as an inhibitory autoreceptor on POMC neurons, we reasoned that peripheral injections of MC3R-specific agonists would act within the arcuate nucleus to inhibit POMC neurons and thereby stimulate feeding. We demonstrate that the peptidergic MC3R agonist, d-Trp(8)-gamma-MSH, stimulates feeding via the MC3R when injected peripherally. These data provide the first evidence that feeding can be stimulated by peripheral injection of MC3R-specific agonists.     

Arthropod FMRFamide-related peptides modulate muscle activity in helminths

FMRFamide-related peptides are common to a wide variety of invertebrate species, including helminths and arthropods. In arthropods, five distinct FMRFamide-related peptide subfamilies are recognised: the myosuppressins, extended-FLRFamides, -FMRFamides, -RFamides, and sulfakinins, members of which induce potent and diverse myotropic effects. Whilst >80 FMRFamide-related peptides have been identified in nematodes, only four FMRFamide-related peptides have been characterised from flatworms. The Ascaris suum ovijector/body wall bioassay and the Procerodes littoralis muscle fibre bioassay have proved both reliable and sensitive systems for assessing the functional activities of FMRFamide-related peptides in vitro, and data describing the effects of native FMRFamide-related peptides in these systems are rapidly accumulating. This is the first study to determine the cross-phyla activities of non-native FMRFamide-related peptides in both nematode and flatworm species. In the present study, the effects of 10 arthropod FMRFamide-related peptides (leucomyosuppressin [pQDVDHVFLRFamide], schistoFLRFamide [PDVDHVFLRFamide] and truncated analogues [HVFLRFamide and VFLRFamide], lobster peptide I [TNRNFLRFamide], lobster peptide II [SDRNFLRFamide], manducaFLRFamide II [GNSFLRFamide], manducaFLRFamide III [DPSFLRFamide], calliFMRFamide 4 [KPNQDFMRFamide] and perisulfakinin [EQFDDY(SO(3)H)GHMRFamide]), representing the five subfamilies, were examined on the body wall and ovijector of the parasitic porcine nematode, A. suum and dispersed muscle fibres from the free-living turbellarian, P. littoralis. The muscle activity of the ovijector was found to be modulated significantly by each of the arthropod FMRFamide-related peptides tested; the effects were concentration-dependent, reversible and repeatable. All but one (perisulfakinin) of the 10 arthropod FMRFamide-related peptides examined modulated significantly the activity of A. suum body wall muscle. In addition, all of the arthropod FMRFamide-related peptides examined induced potent concentration-dependent contractions of P. littoralis muscle fibres. These results reveal similarities in the ligand requirement(s) between FMRFamide-related peptide receptors within the Phyla Arthropoda, Nematoda and Platyhelminthes, and indicate significant receptor promiscuity, which highlights the potential of FMRFamide-related peptide receptors as legitimate targets for novel endectocidal agents.     

Peptidomics of the Agriculturally Damaging Larval Stage of the Cabbage Root Fly Delia radicum (Diptera: Anthomyiidae)

The larvae of the cabbage root fly induce serious damage to cultivated crops of the family Brassicaceae. We here report the biochemical characterisation of neuropeptides from the central nervous system and neurohemal organs, as well as regulatory peptides from enteroendocrine midgut cells of the cabbage maggot. By LC-MALDI-TOF/TOF and chemical labelling with 4-sulfophenyl isothiocyanate, 38 peptides could be identified, representing major insect peptide families: allatostatin A, allatostatin C, FMRFamide-like peptides, kinin, CAPA peptides, pyrokinins, sNPF, myosuppressin, corazonin, SIFamide, sulfakinins, tachykinins, NPLP1-peptides, adipokinetic hormone and CCHamide 1. We also report a new peptide (Yamide) which appears to be homolog to an amidated eclosion hormone-associated peptide in several Drosophila species. Immunocytochemical characterisation of the distribution of several classes of peptide-immunoreactive neurons and enteroendocrine cells shows a very similar but not identical peptide distribution to Drosophila. Since peptides regulate many vital physiological and behavioural processes such as moulting or feeding, our data may initiate the pharmacological testing and development of new specific peptide-based protection methods against the cabbage root fly and its larva.     

FaRP cell distribution in the developing CNS suggests the involvement of FaRPs in all parts of the chromatophore control pathway in Sepia officinalis (Cephalopoda)

The FMRFamide-related peptide (FaRP) family includes a wide range of neuropeptides that have a role in many biological functions. In cephalopods, these peptides intervene in the peculiar body patterning system used for communication and camouflage. This system is particularly well developed in the cuttlefish and is functional immediately after hatching (stage 30). In this study, we investigate when and how the neural structures involved in the control of body patterning emerge and combine during Sepia embryogenesis, by studying the expression or the production of FaRPs. We detected FaRP expression and production in the nervous system of embryos from the beginning of organogenesis (stage 16). The wider FaRP expression was observed concomitantly with brain differentiation (around stage 22). Until hatching, FaRP-positive cells were located in specific areas of the central and peripheral nervous system (CNS and PNS). Most of these areas were implicated in the control of body patterns, suggesting that FaRPs are involved in all parts of the neural body pattern control system, from the ‘receptive areas’ via the CNS to the chromatophore effectors.