Ganglia Of Ventral Nerve Cord Research Articles

E2F1 Expression and Apoptosis Initiation in Crayfish and Rat Peripheral Neurons and Glial Cells after Axonal Injury.

Neurotrauma is among the main causes of human disability and mortality. The transcription factor E2F1 is one of the key proteins that determine the fate of cells. The involvement of E2F1 in the regulation of survival and death of peripheral nerve cells after axotomy has not been previously studied. We, for the first time, studied axotomy-induced changes in the expression and localization of E2F1 following axonal injury in rats and crayfish. Immunoblotting and immunofluorescence microscopy were used for the analysis of the expression and intracellular localization of E2F1 and its changes after axotomy. To evaluate whether this transcription factor promotes cell apoptosis, we examined the effect of pharmacological inhibition of E2F activity in axotomized rat models. In this work, axotomy caused increased expression of E2F1 as early as 4 h and even 1 h after axotomy of mechanoreceptor neurons and ganglia of crayfish ventral nerve cord (VNC), as well as rat dorsal root ganglia (DRG). The level of E2F1 expression increased both in the cytoplasm and the nuclei of neurons. Pharmacological inhibition of E2F demonstrated a pronounced neuroprotective activity against axotomized DRGs. E2F1 and downstream targets could be considered promising molecular targets for the development of potential neuroprotective agents.

Axotomy-Induced Changes of the Protein Profile in the Crayfish Ventral Cord Ganglia.

We suggest novel experimental model of nerve injury-bilaterally axotomized ganglia of the crayfish ventral nerve cord (VNC). Using proteomic antibody microarrays, we showed upregulation of apoptosis execution proteins (Bcl-10, caspases 3, 6, and 7, SMAC/DIABLO, AIF), proapoptotic signaling proteins and transcription factors (c-Myc, p38, E2F1, p53, GADD153), and multifunctional proteins capable of initiating apoptosis in specific situations (p75, NMDAR2a) in the axotomized VNC ganglia. Simultaneously, anti-apoptotic proteins (p21WAF-1, MDM2, Bcl-x, Mcl-1, MKP1, MAKAPK2, ERK5, APP, calmodulin, estrogen receptor) were overexpressed. Some proteins associated with actin cytoskeleton (α-catenin, catenin p120CTN, cofilin, p35, myosin Vα) were upregulated, whereas other actin-associated proteins (ezrin, distrophin, tropomyosin, spectrin (α + β), phosphorylated Pyk2) were downregulated. Various cytokeratins and βIV-tubulin, components of intermediate filament and microtubule cytoskeletons, were also downregulated that could be the result of tissue destruction. Downregulation of proteins involved in clathrin vesicle formation (AP2α and AP2γ, adaptin (β1 + β2), and syntaxin) indicated impairment of vesicular transport and synaptic processes. The levels of L-DOPA decarboxylase, tyrosine, and tryptophan hydroxylases that mediate synthesis of serotonin, dopamine, norepinephrine, and epinephrine decreased. Overexpression of histone deacetylases HDAC1, HDAC2, and HDAC4 contributed to suppression of transcription and protein synthesis. So, the balance of multidirectional processes aimed either at cell death, or to repair and recovery, determines the cell fate. Present data provide integral, albeit incomplete, view on the nervous tissue response to axotomy. Some of these proteins can be probably potential markers of nerve injury and targets for neuroprotective therapy.

A population of descending tyraminergic/octopaminergic projection neurons of the insect deutocerebrum.

In this study, we describe a cluster of tyraminergic/octopaminergic neurons in the lateral dorsal deutocerebrum of desert locusts (Schistocerca gregaria) with descending axons to the abdominal ganglia. In the locust, these neurons synthesize octopamine from tyramine stress-dependently. Electrophysiological recordings in locusts reveal that they respond to mechanosensory touch stimuli delivered to various parts of the body including the antennae. A similar cluster of tyraminergic/octopaminergic neurons was also identified in the American cockroach (Periplaneta americana) and the pink winged stick insect (Sipyloidea sipylus). It is suggested that these neurons release octopamine in the ventral nerve cord ganglia and, most likely, convey information on arousal and/or stressful stimuli to neuronal circuits thus contributing to the many actions of octopamine in the central nervous system.

Phylogenetic analysis reveals high local endemism and clear biogeographic breaks in southern African stoneflies (Notonemouridae, Plecoptera).

The low vagility of the southern African Notonemouridae (stoneflies, Plecoptera), and their restriction to temperate montane refugia, make them a useful model for examining the evolution and biogeography of the rich palaeogenic fauna of the region. Here we use maximum parsimony tree reconstruction based on morphological characters and a partial COI mtDNA sequence to explore the evolutionary history and biogeography of the family in southern Africa. Morphological and molecular parsimony cladograms were largely in agreement, and supported monophyly of all six genera in the region. Previously undocumented morphological features in Plecoptera are identified: the first record of paraproct glands, and the presence of paired spermathecae in Aphanicercopsis Barnard females (all other Plecoptera have a single or a divided spermatheca). Some phylogenetically useful characters were the degree of fusion of the ventral abdominal nerve cord ganglia, male paraproct glands (presence and shape), and accessory glands of the male seminal vesicle. Two main biogeographic zones were defined: Eastern Highlands and the Cape Fold Mountains, with an additional outlying zone, the Namaqualand Highlands. Almost 41% of species were endemic to a single mountain range group. The most species-rich region was the intersection of the Southern and Western Cape Fold Mountains. It is hypothesized that, after the separation of Gondwanaland, the common ancestor of the region's six genera dispersed from a Cape Fold Mountain origin to the Amatola and Drakensberg montane areas of the southern tip of the African continent. The high number of species within the Cape Fold Mountains compared to other mountain ranges in the region is likely a reflection of the topographic complexity of this mountain system and its influence on vicariant events.

NADPH-diaphorase histochemistry selectively stains peripheral and central sensory structures of lumbricid earhworms.

By means of whole mount NADPH-diaphorase histochemistry the distribution pattern of primary sensory cells (PSC) and the pathway of their central processes in the ventral nerve cord (VNC) ganglia were investigated in the lumbricid earthworms, Eisenia fetida and Lumbricus terrestris. The distribution pattern of the stained structures seemed to be the same in both species investigated. Strong labelling occurred in sensory fibre branches of segmental nerves and in each of the sensory longitudinal axon bundles of VNC ganglia. Based on their anatomical location some NADPH-d positive central sensory cells were identified from among which the putative tactile receptors were characterized by constant, strong staining.

Neuroendocrine control of posterior regeneration in tropical earthworm, Eudrilus eugeniae (Kinberg)

Eudrilus eugeniae (Kinberg), well known vermicomposting earthworms, are often subjected to predator attacks leading to loss of body parts due to their surface living habit. Thus nature has gifted them the power of regeneration of lost body parts. As neurosecretion is the sole source of hormone in oligochaetes, we hypothesize that neurohormone secreted from the neurosecretory cells of the central nervous system (CNS) will control the phenomenon of regeneration in earthworms. In Eudrilus eugeniae, appearance of regeneration blastema was noticed within 72 h of posterior amputation. In fact, posterior amputation brought about multiple cytoplasmic alteration in the neurosecretory cells (NSCs) viz. deep stained A cells and moderately stained B cells in cerebral ganglia, deep stained 'U' cells and moderately stained B cells in the sub-esophageal and ventral nerve cord ganglia. Massive depletion followed by marginal accumulation of NSM in the NSCs following 24 h and 48 h of amputation were recorded. Thereafter (72 h and 96 h of amputation) moderate to massive engorgement of NSM in the B cells, coupled with spectacular increase in number of A cells were noticed. Sequential changes involved in the secretory dynamics of NSCs, as well as, NSM accumulation both within and periphery of the ganglia (perineurium) provides evidence for the utilization of materials through repaired vascular systems during posterior regeneration in E. eugeniae.

Fine taxonomic sampling of nervous systems within Naididae (Annelida: Clitellata) reveals evolutionary lability and revised homologies of annelid neural components.

IntroductionAn important goal for understanding how animals have evolved is to reconstruct the ancestral features and evolution of the nervous system. Many inferences about nervous system evolution are weak because of sparse taxonomic sampling and deep phylogenetic distances among species compared. Increasing sampling within clades can strengthen inferences by revealing which features are conserved and which are variable within them. Among the Annelida, the segmented worms, the Clitellata are typically considered as having a largely conserved neural architecture, though this view is based on limited sampling.ResultsTo gain better understanding of nervous system evolution within Clitellata, we used immunohistochemistry and confocal laser scanning microscopy to describe the nervous system architecture of 12 species of the basally branching family Naididae. Although we found considerable similarity in the nervous system architecture of naidids and that of other clitellate groups, our study identified a number of features that are variable within this family, including some that are variable even among relatively closely related species. Variable features include the position of the brain, the number of ciliary sense organs, the presence of septate ventral nerve cord ganglia, the distribution of serotonergic cells in the brain and ventral ganglia, and the number of peripheral segmental nerves.ConclusionsOur analysis of patterns of serotonin immunoreactive perikarya in the central nervous system indicates that segmental units are not structurally homogeneous, and preliminary homology assessments suggest that whole sets of serotonin immunoreactive cells have been gained and lost across the Clitellata. We also found that the relative position of neuroectodermal and mesodermal segmental components is surprisingly evolutionarily labile; in turn, this revealed that scoring segmental nerves by their position relative to segmental ganglia rather than to segmental septa clarifies their homologies across Annelida. We conclude that fine taxonomic sampling in comparative studies aimed at elucidating the evolution of morphological diversity is fundamental for proper assessment of trait variability.Electronic supplementary materialThe online version of this article (doi:10.1186/s12983-015-0100-6) contains supplementary material, which is available to authorized users.

The method of isolation of the crayfish abdominal stretch receptor maintaining a connection of the sensory neuron to the ventral nerve cord ganglion.

The crayfish stretch receptor consisting of the single mechanoreceptor neurons enveloped by satellite glial cells is the simplest functioning neuroglial preparation. However, during isolation, its axons are usually transected that eliminates afferent regulation and induces complex axotomy-related signaling responses in neurons and satellite glia. We developed new microsurgical method of crayfish stretch receptor isolation, which preserves connections of sensory neurons to the ventral nerve cord ganglion. The stretch receptor may either remain on the abdominal carapace, or be completely isolated. In both cases, it may be either intact, or axotomized. The integrity of axons was confirmed by firing recording from proximal and distal axon points. Normal, necrotic and apoptotic cells were visualized using double fluorochroming with Hoechst 33342 and propidium iodide. The isolated mechanoreceptor neurons maintain regular firing during 8-10 or more hours. Glial cells surrounding non-axotomized neurons demonstrate lower necrosis and apoptosis levels than the axotomized ones. Unlike the existing method, in which the sensory neurons were axotomized, the present method preserves links between the sensory neurons and the ganglion and makes possible to avoid consequences of axotomy in neurons and satellite glia. The present neuroglial preparation may be used as a simple but informative model object in studies of axotomy-induced degeneration and survival of peripheral neurons, the role of glia in neuron injury, the signaling mechanisms of neuroglial interactions, and the effects of diverse physical and chemical factors on neuronal and glial cells.

Organization of the sensory system of the earthworm Lumbricus terrestris (Annelida, Clitellata) visualized by DiI

The anatomical organization of the peripheral and central sensory structures of the earthworm Lumbricus terrestris was investigated applying a fluorescent carbocyanine dye (DiI) as a neuronal tracer. Using whole-mount preparations and confocal laser scanning microscopy, the pattern of primary sensory cells and pathways of their processes were traced and reconstructed in three-dimensions. Our study shows that a ventral nerve cord ganglion receives sensory fibers from at least two adjacent segments suggesting that the peripheral nervous system is not segmental in its arrangement and the receptive-fields of the body wall overlap in earthworms. Furthermore, our result suggests an integrative function of the basiepidermal plexus consists of sensory and motor fibers.

Ultrastructure and molecular characterization of a microsporidium, Tubulinosema hippodamiae, from the convergent lady beetle, Hippodamia convergens Guérin-Méneville

Hippodamia convergens, the convergent lady beetle, is available for aphid control in home gardens and in commercial food production systems throughout the United States and Canada. Beetles received from commercial insectaries for biological control are occasionally infected with a microsporidium. The objective of this study was to describe the pathogen by means of ultrastructure, molecular characterization and tissue pathology. All stages of the microsporidium were in direct contact with the host cell cytoplasm. Early developmental stages were proximal to mature spores and both were observed throughout the tissue sections that were examined. Merogony resulted from binary fission. Early-stage sporoblasts were surrounded by a highly convoluted plasma membrane and contained an electron-dense cytoplasm and diplokaryon. Ovoid to elongated late-stage sporoblasts were surrounded by a relatively complete spore wall. The polar filament, polaroplast, and anchoring disk were readily observed within the cell cytoplasm. Mature spores were typical of terrestrial microsporidia, with a thickened endospore surrounded by a thin exospore. Spores contained well-defined internal structures, including a diplokaryon, lamellar polaroplast and a slightly anisofilar polar filament with 10–14 coils arranged in a single or double row. A prominent indentation was evident at the apical end of the spore wall proximal to the anchoring disk. Aberrant spores were also observed. These had a fully developed endospore and exospore but lacked any discernable internal spore structures, and were, instead, filled with lamellar or vesicular structures. Typical and aberrant spores measured 3.58 ± 0.2 × 2.06 ± 0.2 μm ( n = 10) and 3.38 ± 0.8 × 2.13 ± 0.2 μm ( n = 10), respectively. Spores were observed in longitudinal muscle surrounding the midgut and within the fat body, Malpighian tubules, pyloric valve epithelium, ventral nerve cord ganglia, muscles and ovaries. The hindgut epithelium was often infected but the connective tissues were rarely invaded. The life cycle and pathology of the microsporidium bears some resemblance to Nosema hippodamiae, the only microsporidium reported from H. convergens by Lipa and Steinhaus in 1959. Molecular characterization of the pathogen genomic DNA revealed that it is 99% similar to Tubulinosema acridophagus and T. ratisbonensis, two pathogens that infect Drosophila melanogaster and 98% similar to T. kingi from D. willistoni. Based on similarities in pathogen ultrastructure and the molecular information gained during this study, we propose that the microsporidium in H. convergens be given the name Tubulinosema hippodamiae.

Pituitary adenylate cyclase-activating polypeptide type 1 (PAC1) receptor is expressed during embryonic development of the earthworm

Pituitary adenylate cyclase activating polypeptide (PACAP)-like molecules have been shown to be present in cocoon albumin and in Eisenia fetida embryos at an early developmental stage (E1) by immunocytochemistry and radioimmunoassay. Here, we focus on detecting the stage at which PAC1 receptor (PAC1R)-like immunoreactivity first appears in germinal layers and structures, e.g., various parts of the central nervous system (CNS), in developing earthworm embryos. PAC1R-like immunoreactivity was revealed by Western blot and Far Western blot as early as the E2 developmental stage, occurring in the ectoderm and later in specific neurons of the developing CNS. Labeled CNS neurons were first seen in the supraesophageal ganglion (brain) and subsequently in the subesophageal and ventral nerve cord ganglia. Ultrastructurally, PAC1Rs were located mainly on plasma membranes and intracellular membranes, especially on cisternae of the endoplasmic reticulum. Therefore, PACAP-like compounds probably influence the differentiation of germinal layers (at least the ectoderm) and of some neurons and might act as signaling molecules during earthworm embryonic development.

Characterization of neuronal apoptosis in the ventral ganglia of postembryonic silkworms Bombyx mori (Lepidoptera: Bombycidae)

A fluorescent triple staining method was developed to stain the cytoplasm of neurons red, the nuclei of all kinds of cells, including neurons, blue and the nuclei of apoptotic neurons in cyan in the twelve ventral ganglia (VG) of the Bombyx mori ventral nerve cord. This differential staining method was used to distinguish between apoptotic and normal neurons in the suboesophageal ganglion (SOG), thoracic ganglia (TG)1 to TG3 and abdominal ganglia (AG)1 to AG8 and also determine the changes in the num- bers of apoptotic neurons that occur during postembryonic development. In most of the VG tested, neuronal apoptosis was most marked during the period from the end of larval life to the mid pupal stage. The greatest number of apoptotic neurons was found in SOG of day-5 pupae, TG1 to TG3 and AG1 to AG4 of day-1 pupae, and AG5 to AG8 of day-4 pupae. In vivo injection of 20- hydroxyecdysone (20E) into day-8 5th instar larvae resulted in both a considerable increase in the number of apoptotic neurons and cleavage of procaspase-3 into caspase-3, which induced neuronal apoptosis in SOG and AG6 to AG8 in day-1 pupae, and a slight increase in the number of apoptotic neurons in TG1. In TG3 and AG4, however, it had little effect on the number of apoptotic neu- rons or cleavage of procaspase-3. Treatment of the VG of both day-8 5th instar larvae and day-2 pupae with protein synthesis inhibi- tors by in vivo injection triggered a significant inhibition of neuronal apoptosis and procaspase-3 cleavage in most of these ganglia in day-1 pupae and day-4 pupae, but not TG3 and AG4, in which there was little procaspase-3 and caspase-3. In vivo injection of caspase-8 and -3 inhibitors into day-8 5th instar larvae and day-2 pupae led to a substantial inhibition of neuronal apoptosis and of procaspase-3 cleavage in SOG, AG6 and TAG, but not in TG3 or AG4 of day-1 pupae and day-4 pupae. These findings suggest that neurons that die in SOG, TG1 and AG6 to AG8 in day-1 and -4 pupae may undergo apoptosis induced by the synthesis of a new pro- tein and caspase-8- and -3-implicated signal transduction by the increase in titre of 20E in the haemolymph but not the neuronal aopotosis in TG3 and AG4. This study provides neurobiologists with valuable information and a means of studying neuronal apop- tosis in the nervous system of insects.

Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetida

AbstractPeriviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR( L/I)amide, SPLPR( L/I)amide, SFVR( L/I)amide, AFVR( L/I)amide, and SPAFVR( L/I)amide, were identified in the central nervous system with the common‐XR( L/I)amide C‐terminal sequence. The exact anatomical position of 13 labeled XR( I/L)amide expressing neuron groups and numerous peptide‐containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole‐mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine‐fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister‐groups of animals such as annelids, mollusks, and insects. J. Comp. Neurol. 514:415–432, 2009. © 2009 Wiley‐Liss, Inc.

Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetida

AbstractPeriviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR(L/I)amide, SPLPR(L/I)amide, SFVR(L/I)amide, AFVR(L/I)amide, and SPAFVR(L/I)amide, were identified in the central nervous system with the common −XR(L/I)amide C‐terminal sequence. The exact anatomical position of 13 labeled XR(I/L)amide expressing neuron groups and numerous peptide‐containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole‐mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine‐fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister‐groups of animals such as annelids, mollusks, and insects. J. Comp. Neurol. 514:415–432, 2009. © 2009 Wiley‐Liss, Inc.

Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetida

Periviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR(L/I)amide, SPLPR(L/I)amide, SFVR(L/I)amide, AFVR(L/I)amide, and SPAFVR(L/I)amide, were identified in the central nervous system with the common -XR(L/I)amide C-terminal sequence. The exact anatomical position of 13 labeled XR(I/L)amide expressing neuron groups and numerous peptide-containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole-mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine-fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister-groups of animals such as annelids, mollusks, and insects.

Expression of PACAP-Like Compounds During the Caudal Regeneration of the Earthworm Eisenia fetida

The regeneration of the ventral nerve cord ganglion and peripheral tissues was investigated by radioimmunoassay and immunohistochemistry in the model animal, Eisenia fetida (Annelida, Oligochaeta). It is now well-established that pituitary adenylate cyclase-activating polypeptide (PACAP) is a neurotrophic factor, playing important roles in the development of the nervous system in vertebrate animals. Based on the apparent evolutionary conservation of PACAP and on the several common mechanisms of vertebrate and invertebrate nervous regeneration, the question was raised whether PACAP has any role in the regeneration of the earthworm nervous system. As a first step, we studied the distribution, concentration, and time-course of PACAP-like immunoreactivity during caudal regeneration of both lost segments and the ventral nerve cord ganglia in E. fetida. A strong upregulation of PACAP-like immunoreactivity was observed in most tissues following injury as determined by radioimmunoassay and immunohistochemistry. Significant increases in the concentration of PACAP-like compounds were found in the body wall, alimentary canal, and in coelomocytes. The most characteristic morphological feature was the accumulation of immunolabeled neoblasts in the injured tissues, especially in the ventral nerve cord ganglion that initiates and mediates regeneration processes. Our present results show that PACAP/PACAP-like peptides accumulate in the regenerating tissues of the earthworm, suggesting trophic functions of these compounds in earthworm tissues similarly to vertebrate species.

Neurosecretory System of Millipede Gonoplectus malayus (CARL.) (Myriapoda, Diplopoda)

The neurosecretory system of millipede G. malayus has been described using PF and CHP techniques in whole mounts and sections. Three types of neurosecretory cells namely A, B and C have been observed distributed in definite regions of the brain and ganglia of ventral nerve cord. Neurosecretory products released from these cells, travel through definite pathways and ultimately are stored in the neurohaemal organs i.e. in the cerebral glands and connective bodies. Some cells directly release their neurosecretory materials in the adjacent neuropile masses.

PAC1 receptor localization in a model nervous system: Light and electron microscopic immunocytochemistry on the earthworm ventral nerve cord ganglia

The presence and pattern of pituitary adenylate cyclase activating polypeptide (PACAP) type I (PAC1) receptors were identified by means of pre- and post-embedding immunocytochemical methods in the ventral nerve cord ganglia (VNC) of the earthworm Eisenia fetida. Light and electron microscopic observations revealed the exact anatomical positions of labeled structures suggesting that PACAP mediates the activity of some interneurons, a few small motoneurons and certain sensory fibers that are located in ventrolateral, ventromedial and intermediomedial sensory longitudinal axon bundles of the VNC ganglia. No labeling was located on large interneuronal systems such as dorsal medial and lateral giant axon systems and ventral giant axons. At the ultrastructural level labeling was mainly restricted to endo- and plasma membranes showing characteristic unequal distribution in various neuron parts. An increasing abundance of PAC1 receptors located on both rough endoplasmic reticulum and plasma membranes was seen from perikarya to neural processes, indicating that intracellular membrane traffic might play a crucial role in the transportation of PAC1 receptors. High number of PAC1 receptors was found in both pre- and postsynaptic membranes in addition to extrasynaptic sites suggesting that PACAP acts as neurotransmitter and neuromodulator in the earthworm nervous system.

Comparative Anatomy of PACAP‐Immunoreactive Structures in the Ventral Nerve Cord Ganglia of Lumbricid Oligochaetes

By means of a whole mount immunocytochemical approach, the distribution patterns of pituitary adenylate cyclase-activating polypeptide (PACAP)-27 and PACAP-38 were identified in the ventral nerve cord (VNC) ganglia of the earthworms Eisenia fetida and Lumbricus terrestris. Each PACAP form appears to occur in a distinct neuron population. Positions of these populations, as well as numbers and sizes of the constituting neurons do not essentially differ between the two species. The data suggest that in Lumbricid Oligochaetes, PACAP-27 and PACAP-38 neuron populations may mediate distinct physiological processes.

Identification of PBAN-like immunoreactivity in the neuroendocrine system and midgut of Dysdercus cingulatus (Heteroptera: Pyrrhocoridae)

Polyclonal antibodies against PBAN were used to map the distribution of PBAN-like antigenic sites in the brain-suboesophageal ganglion (Br-SOG) complex, associated neurohaemal structures, ventral nerve cord ganglia and in the alimentary canal. A pair of lateral neurosecretory cells immunopositive to the antiserum were found in each half of the deutocerebrum. PBAN-like immunoreactivity (PLI) was also noticed in the tritocerebral region of the brain and in the aorta. Two groups of immunopositive cells of four and two cells respectively, were found in the SOG. Small and weakly immunoreactive neurons were identified in the prothoracic ganglion, whereas in the pterothoracic ganglion a pair of cells reacted positively to the antibody. Immunoreactive cells were also identified in the corpora cardiaca. Some of the epithelial endocrine cells of the midgut also showed immunoreactivity to PBAN antiserum.