FMRFamide-like immunocytochemistry in the brain and subesophageal ganglion of <Emphasis Type="Italic">Triatoma infestans</Emphasis> (Insecta: Heteroptera). Coexpression with β-pigment-dispersing hormone and small cardioactive peptide B

The distribution of FMRFamide (FMRFa)-like immunoreactivity (LI) was studied in the brain and subesophageal ganglion of Triatoma infestans, the insect vector of Chagas disease. The neuropeptide displayed a widespread distribution with immunostained somata in the optic lobe, in the anterior, lateral, and posterior soma rinds of the protocerebrum, and around the antennal sensory and mechanosensory and motor neuropils of the deutocerebrum. FMRFa-immunoreactive profiles of the subesophageal ganglion were seen in the mandibular, maxillary, and labial neuromeres. Immunostained neurites were detected in the medulla and lobula of the optic lobe, the lateral protocerebral neuropil, the median bundle, the calyces and the stalk of the mushroom bodies, and the central body. In the deutocerebrum, the sensory glomeruli showed a higher density of immunoreactive processes than the mechanosensory and motor neuropil, whereas the neuropils of each neuromere of the subesophageal ganglion displayed a moderate density of immunoreactive neurites. Colocalization of FMRFa-LI and crustacean pigment-dispersing hormone-LI was found in perikarya of the proximal optic lobe, the lobula, the sensory deutocerebrum, and the labial neuromere of the subesophageal ganglion. The distribution pattern of small cardioactive peptide B (SCP_B)-LI was also widespread, with immunolabeled somata surrounding every neuropil region of the brain and subesophageal ganglion, except for the optic lobe. FMRFa- and SCP_B-LIs showed extensive colocalization in the brain of this triatomine species. The presence of immunolabeled perikarya displaying either FMRFa- or SCP_B-LI confirmed that each antisera identified different peptide molecules. The distribution of FMRFa immunostaining in T. infestans raises the possibility that FMRFa plays a role in the regulation of circadian rhythmicity. The finding of immunolabeling in neurosecretory somata of the protocerebrum suggests that this neuropeptide may also act as a neurohormone.This work was sponsored by the Facultad de Ciencias Biomédicas, Universidad Austral. Part of this work was performed at the Division of Neurobiology, Arizona Research Laboratories (Tucson, Arizona) with the support of a Fulbright Research Award to B.P.S.     

Distribution and characterization of Corazonin in the central nervous system of Triatoma infestans (Insecta: Heteroptera)

The distribution of corazonin in the central nervous system of the heteropteran insect Triatoma infestans was studied by immunohistochemistry. The presence of corazonin isoforms was investigated using MALDI-TOF mass spectrometry in samples containing the brain, the subesophageal ganglion, the corpora cardiaca-corpus allatum complex and the anterior part of the aorta. Several groups of immunopositive perikarya were detected in the brain, the subesophageal ganglion and the thoracic ganglia. Regarding the brain, three clusters were observed in the protocerebrum. One of these clusters was formed by somata located near the entrance of the ocellar nerves whose fibers supplied the aorta and the corpora cardiaca. The remaining groups of the protocerebrum were located in the lateral soma cortex and at the boundary of the protocerebrum with the optic lobe. The optic lobe housed immunoreactive somata in the medial soma layer of the lobula and at the level of the first optic chiasma. The neuropils of the deutocerebrum and the tritocerebrum were immunostained, but no immunoreactive perikarya were detected. In the subesophageal ganglion, immunostained somata were found in the soma layers of the mandibular and labial neuromeres, whereas in the mesothoracic ganglionic mass, they were observed in the mesothoracic, metathoracic and abdominal neuromeres. Immunostained neurites were also found in the esophageal wall. The distribution pattern of corazonin like immunoreactivity in the central nervous system of this species suggests that corazonin may act as a neurohormone. Mass spectrometric analysis revealed that [Arg⁷]-corazonin was the only isoform of the neuropeptide present in T. infestans tissue samples.     

Localization of cholecystokinin-like immunoreactivity in the central nervous system of Triatoma infestans (Insecta: Heteroptera)

The distribution of cholecystokinin-like immunoreactivity was studied in the central nervous system of the heteropteran insect Triatoma infestans using high-sensitivity immunocytochemistry. In the protocerebrum, CCK-IR somata were observed in the anteromedial, anterolateral and posterior cell-body layers. The neuropils displayed different densities of immunoreactive neurites. Few immunoreactive somata were found in the optic lobe in both the medial and lateral soma rinds, as well as in the proximal optic lobe. Immunoreactive fibers were present in the medulla and lobula neuropils. The sensory deutocerebrum contained a higher number of immunopositive perikarya than the antennal mechanosensory and motor center. The antennal lobe glomeruli displayed a moderate density of immunoreactive fibers. With regard to the subesophageal ganglion, numerous CCK-IR somata were found close to the root of the mandibular nerve; others were present in the soma rind of the remaining neuromeres. CCK-IR perikarya were present in both thoracic ganglia, with the abdominal neuromeres containing the highest number of positive somata. The neuropils of both ganglia showed moderate densities of immunopositive processes. The distribution of CCK-LI in somata and neuropils of central nervous system of T. infestans is widespread suggesting that a CCK-like peptide may act mainly as a neuromodulator in the integration of information from distinct sensory receptors.     

Proctolin in the brain and ganglia of Triatoma infestans (Hemiptera: Reduviidae)

The distribution of proctolin in the central nervous system of the hemipteran bug, Triatoma infestans, was studied by immunohistochemistry using the sensitive avidin‐biotin technique combined with nickel salt intensification of the reaction product. Proctolin was present in cells and fibers of the brain and ganglia. In the brain, protocerebral proctolin‐immunoreactive cell bodies were found in the pars intercerebralis, the optic lobes, and the lateral soma rind. The deutocerebrum showed positive somata in relation to the antennal motor center and the tritocerebrum had intense immunoreactive fibers but few positive cells. Proctolin‐immunoreactive cell bodies of different sizes were observed in the subesophageal ganglion. Large cell bodies were found mainly rostrally and beaded positive processes were present around the ventral border of the esophageal foramen and in the rostrolateral neuropil of this ganglion. Small‐ to medium‐sized positive somata were found in the posterior part of the prothoracic ganglion; some of these cells were sending immunoreactive processes to the central neuropil. The meso‐metathoracic‐abdominal ganglionic mass showed positive cells in all the neuromeres, where some of them were large and had thick immunoreactive granules. The results show that the labeling pattern of proctolin‐like immunoreactivity in Triatoma i. appears to be widespread and unique for its central nervous system. It is suggested that proctolin may serve neuroendocrine, integrative, and motor functions in the brain of T. infestans. J. Morphol. 240:39–47, 1999. © 1999 Wiley‐Liss, Inc.     

CNS microstructure in the wandering wolf spider Arctosa kwangreungensis (Araneae: Lycosidae)

The supraesophageal ganglion of the wolf spider Arctosa kwangreungensis is made up of a protocerebral and tritocerebral ganglion, whereas the subesophageal ganglionic mass is composed of a single pair of pedipalpal ganglia, four pairs of appendage ganglia, and a fused mass of abdominal neuromeres. In the supraesophageal ganglion, complex neuropile masses are located in the protocerebrum which include optic ganglia, the mushroom bodies, and the central body. Characteristically, the only nerves arising from the protocerebrum are the optic nerves, and the neuropiles of the principal eyes are the most thick and abundant in this wandering spider. The central body which is recognized as an important association center is isolated at the posterior of the protocerebrum and appears as a complex of highly condensed neurons. These cells give off fine parallel bundles of axons arranged in the mushroom bodies. The subesophageal nerve mass can be divided into two main tracts on the basis of direction of the neuropiles. The dorsal tracts are contributed to from the motor or interneurons of each ganglion, whereas the ventral tracts are from incoming sensory axons.     

Aminergic neurons in the brain of blowflies and Drosophila: dopamine- and tyrosine hydroxylase-immunoreactive neurons and their relationship with putative histaminergic neurons

Summary The distribution and morphology of neurons reacting with antisera against dopamine (DA), tyrosine hydroxylase (TH) and histamine (HA) were analyzed in the blowflies Calliphora erythrocephala and Phormia terraenovae. TH-immunoreactive (THIR) and HA-immunoreactive (HAIR) neurons were also mapped in the fruitfly Drosophila melanogaster. The antisera against DA and TH specifically labeled the same neurons in the blowflies. About 300 neurons displayed DA immunoreactivity (DAIR) and THIR in the brain and subesophageal ganglion of the blowflies. Most of these neurons were located in bilateral clusters; some were distributed as bilateral pairs, and two ventral unpaired median (VUM) neurons were seen in the subesophageal ganglion. Immunoreactive processes were found in all compartments of the mushroom bodies except the calyces, in all divisions of the central body complex, in the medulla, lobula and lobula plate of the optic lobe, and in non-glomerular neuropil of protocerebrum, tritocerebrum and the subesophageal ganglion. No DA or TH immunoreactivity was seen in the antennal lobes. In Drosophila, neurons homologous to the blowfly neurons were detected with the TH antiserum. In Phormia and Drosophila, 18 HA-immunoreactive neurons were located in the protocerebrum and 2 in the subesophageal ganglion. The HAIR neurons arborized extensively, but except for processes in the lobula, all HAIR processes were seen in non-glomerular neuropil. The deuto- and tritocerebrum was devoid of HAIR processes. Double labeling experiments demonstrated that TH and HA immunoreactivity was not colocalized in any neuron. In some regions there wasm however, substantial superposition between the two systems. The morphology of the extensively arborizing aminergic neurons described suggests that they have modulatory functions in the brain and subesophageal ganglion.     

Expression of serotonin (5-HT) during CNS development of the cephalopod mollusk, Idiosepius notoides

Cephalopods are unique among mollusks in exhibiting an elaborate central nervous system (CNS) and remarkable cognitive abilities. Despite a profound knowledge of the neuroanatomy and neurotransmitter distribution in their adult CNS, little is known about the expression of neurotransmitters during cephalopod development. Here, we identify the first serotonin-immunoreactive (5-HT-ir) neurons during ontogeny and describe the establishment of the 5-HT system in the pygmy squid, Idiosepius notoides. Neurons that are located dorsally to each optic lobe are the first to express 5-HT, albeit only when the lobular neuropils are already quite elaborated. Later, 5-HT is expressed in almost all lobes, with most 5-HT-ir cell somata appearing in the subesophageal mass. Further lobes with numerous 5-HT-ir cell somata are the subvertical and posterior basal lobes and the optic and superior buccal lobes. Hatching squids possess more 5-HT-ir neurons, although the proportions between the individual brain lobes remain the same. The majority of 5-HT-ir cell somata appears to be retained in the adult CNS. The overall distribution of 5-HT-ir elements within the CNS of adult I. notoides resembles that of adult Octopus vulgaris and Sepia officinalis. The superior frontal lobe of all three species possesses few or no 5-HT-ir cell somata, whereas the superior buccal lobe comprises many cell somata. The absence of 5-HT-ir cell somata in the inferior buccal lobes of cephalopods and the buccal ganglia of gastropods may constitute immunochemical evidence of their homology. This integrative work forms the basis for future studies comparing molluscan, lophotrochozoan, ecdysozoan, and vertebrate brains.     

Crustacean cardioactive peptide-immunoreactive neurons innervating brain neuropils,retrocerebral complex and stomatogastric nervous system of the locust,Locusta migratoria

The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.     

Patterns of serotonin-immunoreactive neurons in the central nervous system of the earthworm Lumbricus terrestris L.

Summary The distribution patterns of serotonin-immunoreactive somata in the cerebral and subpharyngeal ganglion, and in the head and tail ganglia of the nerve cord of Lumbricus terrestris are described from whole-mount preparations. A small number of serotonin-immunoreactive neurons occurs in the cerebral ganglion, in contrast to the large population of serotonin-immunoreactive neurons that exists in all parts of the ventral nerve cord. From the arrangement of serotonin-immunoreactive somata in the subpharyngeal ganglion, we suggest that this ganglion arises from the fusion of two primordial ganglia. In head and tail ganglia, the distribution of serotonin-immunoreactive somata resembles that in midbody segments. Segmental variations in the pattern and number of serotonin-immunoreactive somata in the different body regions are discussed on the background of known developmental mechanisms that result in metameric neuronal populations in annelids and arthropods.Abbreviations CG1, CG2 cerebral soma group 1, 2 - CNS central nervous system - GINs giant interneurons - 5-HT 5-hydroxytryptamine, serotonin - 5-HTi 5-HT-immunoreactive - N side nerve - SG19 subpharyngeal soma group 1–9 - SN segmental nerve     

Localization of pigment-dispersing hormone (PDH) immunoreactivity in the central nervous system of Carcinus maenas and Orconectes limosus (Crustacea), with reference to FMRFamide immunoreactivity in O. limosus

Summary By use of antisera raised against synthetic pigment-dispersing hormone (PDH) of Uca pugilator and FMRFamide, the distribution of immunoreactive structures in the central nervous system (CNS) of Carcinus maenas and Orconectes limosus was studied by light microscopy. In both species, a total of 10–12 PDH-positive perikarya occur amongst the anterior medial, dorsal lateral and angular somata of the cerebral ganglion (CG). In C. maenas, one PDH-perikaryon was found in each commissural ganglion (COG) and several more in the thoracic ganglion. In O. limosus, only four immunopositive perikarya could be demonstrated in the ventral nerve cord, i.e., two somata in the anterior and two in the posterior region of the suboesophageal ganglion (SOG). PDH-immunoreactive tracts and fiber plexuses were present in all central ganglia of both species, and individual axons were observed in the connectives. FMRFamide-immunoreactivity was studied in O. limosus only. Neurons of different morphological types were found throughout the entire CNS, including numerous perikarya in the anterior medial, anterior olfactory, dorsal lateral and posterior cell groups of the CG. Four perikarya were found in the COG, six large and numerous smaller ones in the SOG, and up to eight cells in each of the thoracic and abdominal ganglia. In each ganglion, the perikarya form fiber plexuses. Axons from neurons belonging to the CG could be traced into the ventral nerve cord; nerve fibers arising from perikarya in the SOG appeared to project to the posterior ganglia. In none of the structures examined colocalization of PDH- and FMRF-amide-immunoreactivity was observed.Dedicated to Prof. K.-E. Wohlfarth-Bottermann on the occasion of his 65th birthday     

Tyrosine hydroxylase in the cerebral ganglia of the American cockroach (Periplaneta americana L.): an immunohistochemical study

We have investigated the distribution of tyrosine-hydroxylase-like immunoreactivity in the cerebral ganglia of the American cockroach, Periplaneta americana. Groups of tyrosine-hydroxylase-immunoreactive cell bodies occur in various parts of the three regions of the cerebral ganglia. In the protocerebrum, single large neurons or small groups of neurons are located in the lateral neuropil, adjacent to the calyces, and in the dorsal portion of the pars intercerebralis. Small scattered cell bodies are found in the outer layers of the optic lobe, and clusters of larger cell bodies can be found in the deutocerebrum, medial and lateral to the antennal glomeruli. Thick bundles of tyrosine-hydroxylase-positive nerve fibers traverse the neuropil in the proto- and deutocerebrum and innervate the glomerular and the nonglomerular neuropil with fine varicose terminals. Dense terminal patterns are present in the medulla and lobula of the optic lobe, the pars intercerebralis, the medial tritocerebrum, and the area surrounding the antennal glomeruli, the central body and the mushroom bodies. The pattern of tyrosine-hydroxylase-like immunoreactivity is similar to that previously described for catecholaminergic neurons, but it is distinctly different from the distribution of histaminergic and serotonergic neurons.     

Central projections of first-order ocellar interneurons in the bug Triatoma infestans (Heteroptera: Reduviidae)

The projections of first-order ocellar interneurons were analyzed in the hematophagous bug Triatoma infestans by cobalt filling. The axons run between the calyces of the mushroom bodies and dorsal of the central body to different regions of the brain and the subesophageal and thoracic ganglia. The interneurons can be grouped into large L cells and small S cells. The L cells have cell bodies ranging from 11.5 to 25 μm and axons ranging from 8 to 25 μm diameter (measured in the ocellar nerve); the S cells have smaller cell bodies of 9 μm or less and axon diameters less than 5 μm. The projections of ten L cells are described in detail; they project to the protocerebral posterior slope (PS), the other ocellus (O), the optic neuropile, and the subesophageal, pro-, meso-, and metathoracic ganglia, either to ipsi- (PS I, II), or contra- (PS IV, V), or bilateral areas. In this case projections occur to the same areas (PSO, PS III) or different areas at each side (PSOE; E = eye). Large-descending (LD) first-order interneurons project to the contralateral posterior slope of the protocerebrum, the deutocerebrum, and subesophageal, pro-, mesa-, and metathoracic areas (LD I-III). Cell bodies are located in the dorsal protocerebral lobes and pars intercerebralis, except the PS II neuron and three LD cells, which are located in the ipsilateral posterior protocerebrum. This is the first report about ocellar pathways in Hemiptera. Their adaptive function is discussed with reference to the bugs' behavior as Chagas disease vectors. © 1996 Wiley-Liss, Inc.     

Serotonin-immunoreactive neurons in the antennal sensory system of the brain in the carpenter ant, Camponotus japonicus

Social Hymenoptera such as ants or honeybees are known for their extensive behavioral repertories and plasticity. Neurons containing biogenic amines appear to play a major role in controlling behavioral plasticity in these insects. Here we describe the morphology of prominent serotonin-immunoreactive neurons of the antennal sensory system in the brain of an ant, Camponotus japonicus. Immunoreactive fibers were distributed throughout the brain and the subesophageal ganglion (SOG). The complete profile of a calycal input neuron was identified. The soma and dendritic elements are contralaterally located in the lateral protocerebrum. The neuron supplies varicose axon terminals in the lip regions of the calyces of the mushroom body, axon collaterals in the basal ring but not in the collar region, and other axon terminals ipsilaterally in the lateral protocerebrum. A giant neuron innervating the antennal lobe has varicose axon terminals in most of 300 glomeruli in the ventral region of the antennal lobe (AL) and a thick neurite that spans the entire SOG and continues towards the thoracic ganglia. However, neither a soma nor a dendritic element of this neuron was found in the brain or the SOG. A deutocerebral projection neuron has a soma in the lateral cell-body group of the AL, neuronal branches at most of the 12 glomeruli in the dorsocentral region of the ipsilateral AL, and varicose terminal arborizations in both hemispheres of the protocerebrum. Based on the present results, tentative subdivisions in neuropils related to the antennal sensory system of the ant brain are discussed.     

Organization of local interneurons in optic glomeruli of the dipterous visual system and comparisons with the antennal lobes

The lateral protocerebrum of the fly's brain is composed of a system of optic glomeruli, the organization of which compares to that of antennal lobe glomeruli. Each optic glomerulus receives converging axon terminals from a unique ensemble of optic lobe output neurons. Glomeruli are interconnected by systems of spiking and nonspiking local interneurons that are morphologically similar to diffuse and polarized local interneurons in the antennal lobes. GABA-like immunoreactive processes richly supply optic glomeruli, which are also invaded by processes originating from the midbrain and subesophageal ganglia. These arrangements support the suggestion that circuits amongst optic glomeruli refine and elaborate visual information carried by optic lobe outputs, relaying data to long-axoned neurons that extend to other parts of the central nervous system including thoracic ganglia. The representation in optic glomeruli of other modalities suggests that gating of visual information by other sensory inputs, a phenomenon documented from the recordings of descending neurons, could occur before the descending neuron dendrites. The present results demonstrate that future studies must consider the roles of other senses in visual processing.     

Fine structure and primary sensory projections of sensilla located in the labial-palp pit organ of Helicoverpa armigera (Insecta)

The fine structure and primary sensory projections of sensilla located in the labial-palp pit organ of the cotton bollworm Helicoverpa armigera (Insecta, Lepidoptera) are investigated by scanning electron and transmission electron microscopy combined with confocal laser scanning microscopy. The pit organ located on the third segment of the labial palp is about 300 μm deep with a 60-μm-wide opening, each structure containing about 1200 sensilla. Two sensillum types have been found, namely hair-shaped and club-shaped sensilla, located on the upper and lower half of the pit, respectively. Most sensilla possess a single dendrite. The dendrite housed by the club-shaped sensilla is often split into several branches or becomes lamellated in the outer segment. As reported previously, the sensory axons of the sensilla in the labial pit organ form a bundle entering the ipsilateral side of the subesophageal ganglion via the labial palp nerve and project to three distinct areas: the labial pit organ glomerulus in each antennal lobe, the subesophageal ganglion and the ventral nerve cord. In the antennal lobe, the labial pit organ glomerulus is innervated by sensory axons from the labial pit organ only; no antennal afferents target this unit. One neuron has been found extending fine processes into the subesophageal ganglion and innervating the labial palp via one branch passing at the base of the labial palp nerve. The soma of this assumed motor neuron is located in the ipsilateral cell body layer of the subesophageal ganglion. Our results provide valuable knowledge concerning the neural circuit encoding information about carbon dioxide and should stimulate further investigations directed at controlling pest species such as H. armigera.     

Effect of the urease-derived peptide Jaburetox on the central nervous system of Triatoma infestans (Insecta: Heteroptera)

Background

Triatoma infestans is the main vector of Chagas'disease in Southern Cone countries. In triatomines, symptoms suggesting neurotoxicity were observed after treatment with Jaburetox (Jbtx), the entomotoxic peptide obtained from jackbean urease. Here, we study its effect in the central nervous system (CNS) of this species.

Methods

Immunohistochemistry, Western blots, immunoprecipitation, two-dimensional electrophoresis, tandem mass spectrometry and enzymatic assays were performed.

Results

Anti-Jbtx antibody labeled somata of the antennal lobe only in Jbtx-treated insects. Western blot assays of nervous tissue using the same antibody reacted with a 61 kDa protein band only in peptide-injected insects. Combination of immunoprecipitation, two-dimensional electrophoresis and tandem mass spectrometry identified UDP-N-acetylglucosamine pyrophosphorylase (UDP-GlcNAcP) as a molecular target for Jbtx. The activity of UDP-GlcNAcP increased significantly in the CNS of Jbtx-treated insects. The effect of Jbtx on the activity of nitric oxide synthase (NOS) and NO production was investigated as NO is a recognized messenger molecule in the CNS of T. infestans. NOS activity and NO levels decreased significantly in CNS homogenates of Jbtx-treated insects.

Conclusions

UDP-GlcNAcP is a molecular target of Jbtx. Jbtx impaired the activity of T. infestans nitrergic system, which may be related with early behavioral effects.

General Significance

We report that the CNS of Triatoma infestans is a target for the entomotoxic peptide and propose that a specific area of the brain is involved. Besides potentially providing tools for control strategies of Chagas' disease vectors our data may be relevant in various fields of research as insect physiology, neurobiology and protein function.     

Analysis of neurotransmitter distribution in brain development of benthic and pelagic octopod cephalopods

The database on neurotransmitter distribution during central nervous system development of cephalopod mollusks is still scarce. We describe the ontogeny of serotonergic (5‐HT‐ir) and FMRFamide‐like immunoreactive (Fa‐lir) neurons in the central nervous system of the benthic Octopus vulgaris and Fa‐lir distribution in the pelagic Argonauta hians. Comparing our data to previous studies, we aim at revealing shared immunochemical domains among coleoid cephalopods, i.e., all cephalopods except nautiluses. During development of O. vulgaris, 5‐HT‐ir and Fa‐lir elements occur relatively late, namely during stage XII, when the brain neuropils are already highly differentiated. In stage XII‐XX individuals, Fa‐lir cell somata are located in the middle and posterior subesophageal mass and in the optic, posterior basal, and superior buccal lobes. 5‐HT is predominately expressed in cell somata of the superior buccal, anterior basal, and optic lobes, as well as in the subesophageal mass. The overall population of Fa‐lir neurons is larger than the one expressing 5‐HT. Fa‐lir elements are distributed throughout homologous brain areas of A. hians and O. vulgaris. We identified neuronal subsets with similar cell number and immunochemical phenotype in coleoids. These are located in corresponding brain regions of developmental stages and adults of O. vulgaris, A. hians, and the decapod squid Idiosepius notoides. O. vulgaris and I. notoides exhibit numerous 5‐HT‐ir cell somata in the superior buccal lobes but none or very few in the inferior buccal lobes. The latter have previously been homologized to the gastropod buccal ganglia, which also lack 5‐HT‐ir cell somata in euthyneuran gastropods. Among coleoids, 5‐HT‐ir neuronal subsets, which are located ventrally to the lateral anterior basal lobes and in the anterior middle subesophageal mass, are candidates for homologous subsets. Contrary to I. notoides, octopods exhibit Fa‐lir cell somata ventrally to the brachial lobes and 5‐HT‐ir cell somata close to the stellate ganglia. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Localization of corticotropin-releasing factor-immunoreactive nervous tissue and colocalization with neuropeptide Y-like substance in the optic lobe and peduncle complex of the octopus (<Emphasis Type="Italic">Octopus vulgaris</Emphasis>)

The distribution of corticotropin-releasing factor (CRF)-like immunoreactivity and its colocalization with neuropeptide Y (NPY)-like substances were investigated in the optic lobe and peduncle complex of the octopus (Octopus vulgaris) using immunohistochemical techniques. In the optic lobe cortex, CRF-immunoreactive (CRF-IR) and NPY-immunonegative varicose fibers were observed in the plexiform layer. In the medulla, CRF-IR somata were seen in the cell islands, and CRF-IR varicose fibers were observed in the neuropil. About half of the CRF-IR structures in the medulla showed NPY-like immunoreactivity. In the peduncle lobe, no CRF-IR somata but abundant CRF-IR varicose fibers were observed, and about half of them showed NPY-like immunoreactivity. In the olfactory lobe, CRF-IR somata and abundant CRF-IR varicose fibers were observed. Almost all the CRF-IR somata located in the posterior olfactory lobule showed NPY-like immunoreactivity, whereas those seen in the median olfactory lobule were immunonegative for NPY. About half of the CRF-IR fibers in the anterior lobule neuropil were immunopositive for NPY, but those in the median and posterior lobule neuropils were immunonegative for NPY. In the optic gland, almost all the CRF-IR varicose fibers were immunoreactive for NPY. Western blot analysis of the optic lobe and peduncle complex indicated that anti-CRF antiserum labeled approximate 16.4- and 14.6-kDa bands and that anti-NPY antiserum labeled an approximate 16.2-kDa band. CRF-IR and NPY-immunoreactive neurons in the optic lobe may participate in the modulation of visual information and those in the optic gland may be involved in the regulation of endocrine function.     

γ-Aminobutyric acid immunostaining in the antennal lobe of the moth <Emphasis Type="Italic">Heliothis virescens</Emphasis> and its colocalization with neuropeptides

The antennal lobe is the primary processing center for olfactory information in insects. To understand further the neural circuitry of this brain area, we have investigated the distribution of γ-aminobutyric acid (GABA) and its colocalization with neuropeptides in the antennal lobe of the noctuid moth Heliothis virescens. Immunocytochemical experiments with an antiserum against GABA showed a large number of labeled somata in the antennal lobe; these somata were located exclusively in the lateral cell cluster. Stained neurites innervating all antennal-lobe glomeruli, including the male-specific macroglomerular complex, suggested a prominent role of GABA in processing olfactory information, including signals from pheromones, interspecifically acting odors, and plant odors. Fibers in two antennocerebral tracts (the middle and dorsal antennocerebral tract) exhibited prominent GABA immunoreactivity. Double-labeling experiments revealed that immunostaining for three neuropeptides, viz., A-type allatostatin, Manduca sexta allatotropin, and FMRFamide-related peptides, was largely colocalized with GABA in cell bodies of the lateral cell cluster. The general absence of peptide immunostaining in the antennocerebral tracts strongly indicated that these peptides were colocalized with GABA in local interneurons of the antennal lobe. In contrast, tachykinin-related peptides occurred in a distinct population of local antennal-lobe neurons that did not exhibit GABA immunostaining. Thus, local interneurons that were not GABAergic were present in the moth antennal lobe. This work was supported by the Norwegian University of Science and Technology (project no. 80902101).     

Fine Structural Analysis of the Central Nervous System in the Spider, Achaearanea tepidariorum (Theridiidae: Araneae)

ABSTRACT Central nervous system (CNS) of arachnids is still mysterious and has a rich unexplored field compare to what is known in insects or crustaceans. The CNS of the spider, Achaearanea tepidariorum, consists of a dorsal brain or supraesophageal ganglion and circumesophageal connectives joining it to the subesophageal mass. As the segmentation of the arachnid brain is still under discussion, we classify the brain as a protocerebral and tritocerebral ganglion depending on the evidences which generally accepted. The subesophageal nerve mass underneath the brain is the foremost part of the ventral nerve cord. All of this nerve mass is totally fused together, and forming subesophageal ganglia in this spider. In the brain, the nerve cells are packed in the frontal, dorsal and lateral areas, but are not absent from the posterior and ventral regions. In addition, the nerve cells of the subesophageal and abdominal ganglia are only restricted to the ventral and ventolateral regions. The CNS of the spider, Achaearanea tepidariorum is similar in feature to the Family Araneidae.