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Abdominal Ganglion (abdominal + ganglion)
Selected AbstractsNitric oxide regulates axonal regeneration in an insect embryonic CNSDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2008Michael Stern Abstract In higher vertebrates, the central nervous system (CNS) is unable to regenerate after injury, at least partially because of growth-inhibiting factors. Invertebrates lack many of these negative regulators, allowing us to study the positive factors in isolation. One possible molecular player in neuronal regeneration is the nitric oxide (NO),cyclic guanosine-monophosphate (cGMP) transduction pathway which is known to regulate axonal growth and neural migration. Here, we present an experimental model in which we study the effect of NO on CNS regeneration in flat-fillet locust embryo preparations in culture after crushing the connectives between abdominal ganglia. Using whole-mount immunofluorescence, we examine the morphology of identified serotonergic neurons, which send a total of four axons through these connectives. After injury, these axons grow out again and reach the neighboring ganglion within 4 days in culture. We quantify the number of regenerating axons within this period and test the effect of drugs that interfere with NO action. Application of exogenous NO or cGMP promotes axonal regeneration, whereas scavenging NO or inhibition of soluble guanylyl cyclase delays regeneration, an effect that can be rescued by application of external cGMP. NO-induced cGMP immunostaining confirms the serotonergic neurons as direct targets for NO. Putative sources of NO are resolved using the NADPH-diaphorase technique. We conclude that NO/cGMP promotes outgrowth of regenerating axons in an insect embryo, and that such embryo-culture systems are useful tools for studying CNS regeneration. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Pigment-dispersing factor in the locust abdominal ganglia may have roles as circulating neurohormone and central neuromodulatorDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2001Magnus G. S. Persson Abstract Pigment-dispersing factor (PDF) is a neuropeptide that has been indicated as a likely output signal from the circadian clock neurons in the brain of Drosophila. In addition to these brain neurons, there are PDF-immunoreactive (PDFI) neurons in the abdominal ganglia of Drosophila and other insects; the function of these neurons is not known. We have analyzed PDFI neurons in the abdominal ganglia of the locust Locusta migratoria. These PDFI neurons can first be detected at about 45% embryonic development and have an adult appearance at about 80%. In each of the abdominal ganglia (A3,A7) there is one pair of lateral PDFI neurons and in each of the A5,A7 ganglia there is additionally a pair of median neurons. The lateral neurons supply varicose branches to neurohemal areas of the lateral heart nerves and perisympathetic organs, whereas the median cells form processes in the terminal abdominal ganglion and supply terminals on the hindgut. Because PDF does not influence hindgut contractility, it is possible that also these median neurons release PDF into the circulation. Release from one or both the PDFI neuron types was confirmed by measurements of PDF-immunoreactivity in hemolymph by enzyme immunoassay. PDF applied to the terminal abdominal ganglion triggers firing of action potentials in motoneurons with axons in the genital nerves of males and the 8th ventral nerve of females. Because this action is blocked in calcium-free saline, it is likely that PDF acts via interneurons. Thus, PDF seems to have a modulatory role in central neuronal circuits of the terminal abdominal ganglion that control muscles of genital organs. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 19,41, 2001 [source] Blockade of the central generator of locomotor rhythm by noncompetitive NMDA receptor antagonists in Drosophila larvaeDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2001Daniel Cattaert Abstract The noncompetitive antagonists of the vertebrate N -methyl- D -aspartate (NMDA) receptor dizocilpine (MK 801) and phencyclidine (PCP), delivered in food, were found to induce a marked and reversible inhibition of locomotor activity in Drosophilamelanogaster larvae. To determine the site of action of these antagonists, we used an in vitro preparation of the Drosophila third-instar larva, preserving the central nervous system and segmental nerves with their connections to muscle fibers of the body wall. Intracellular recordings were made from ventral muscle fibers 6 and 7 in the abdominal segments. In most larvae, long-lasting (>1 h) spontaneous rhythmic motor activities were recorded in the absence of pharmacological activation. After sectioning of the connections between the brain and abdominal ganglia, the rhythm disappeared, but it could be partially restored by perfusing the muscarinic agonist oxotremorine, indicating that the activity was generated in the ventral nerve cord. MK 801 and PCP rapidly and efficiently inhibited the locomotor rhythm in a dose-dependent manner, the rhythm being totally blocked in 2 min with doses over 0.1 mg/mL. In contrast, more hydrophilic competitive NMDA antagonists had no effect on the motor rhythm in this preparation. MK 801 did not affect neuromuscular glutamatergic transmission at similar doses, as demonstrated by monitoring the responses elicited by electrical stimulation of the motor nerve or pressure applied glutamate. The presence of oxotremorine did not prevent the blocking effect of MK 801. These results show that MK 801 and PCP specifically inhibit centrally generated rhythmic activity in Drosophila, and suggest a possible role for NMDA-like receptors in locomotor rhythm control in the insect CNS. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 58,73, 2001 [source] Pigment-dispersing factor in the locust abdominal ganglia may have roles as circulating neurohormone and central neuromodulatorDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2001Magnus G. S. Persson Abstract Pigment-dispersing factor (PDF) is a neuropeptide that has been indicated as a likely output signal from the circadian clock neurons in the brain of Drosophila. In addition to these brain neurons, there are PDF-immunoreactive (PDFI) neurons in the abdominal ganglia of Drosophila and other insects; the function of these neurons is not known. We have analyzed PDFI neurons in the abdominal ganglia of the locust Locusta migratoria. These PDFI neurons can first be detected at about 45% embryonic development and have an adult appearance at about 80%. In each of the abdominal ganglia (A3,A7) there is one pair of lateral PDFI neurons and in each of the A5,A7 ganglia there is additionally a pair of median neurons. The lateral neurons supply varicose branches to neurohemal areas of the lateral heart nerves and perisympathetic organs, whereas the median cells form processes in the terminal abdominal ganglion and supply terminals on the hindgut. Because PDF does not influence hindgut contractility, it is possible that also these median neurons release PDF into the circulation. Release from one or both the PDFI neuron types was confirmed by measurements of PDF-immunoreactivity in hemolymph by enzyme immunoassay. PDF applied to the terminal abdominal ganglion triggers firing of action potentials in motoneurons with axons in the genital nerves of males and the 8th ventral nerve of females. Because this action is blocked in calcium-free saline, it is likely that PDF acts via interneurons. Thus, PDF seems to have a modulatory role in central neuronal circuits of the terminal abdominal ganglion that control muscles of genital organs. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 19,41, 2001 [source] New reproductive anomalies in fruitless -mutant Drosophila males: Extreme lengthening of mating durations and infertility correlated with defective serotonergic innervation of reproductive organsDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2001Gyunghee Lee Abstract Several features of male reproductive behavior are under the neural control of fruitless (fru) in Drosophila melanogaster. This gene is known to influence courtship steps prior to mating, due to the absence of attempted copulation in the behavioral repertoire of most types of fru -mutant males. However, certain combinations of fru mutations allow for fertility. By analyzing such matings and their consequences, we uncovered two striking defects: mating times up to four times the normal average duration of copulation; and frequent infertility, regardless of the time of mating by a given transheterozygous fru -mutant male. The lengthened copulation times may be connected with fru -induced defects in the formation of a male-specific abdominal muscle. Production of sperm and certain seminal fluid proteins are normal in these fru mutants. However, analysis of postmating qualities of females that copulated with transheterozygous mutants strongly implied defects in the ability of these males to transfer sperm and seminal fluids. Such abnormalities may be associated with certain serotonergic neurons in the abdominal ganglion in which production of 5HT is regulated by fru. These cells send processes to contractile muscles of the male's internal sex organs; such projection patterns are aberrant in the semifertile fru mutants. Therefore, the reproductive functions regulated by fruitless are expanded in their scope, encompassing not only the earliest stages of courtship behavior along with almost all subsequent steps in the behavioral sequence, but also more than one component of the culminating events. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 121,149, 2001 [source] Localization of putative nitrergic neurons in peripheral chemosensory areas and the central nervous system of Aplysia californicaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2006Leonid L. Moroz Abstract The distribution of putative nitric oxide synthase (NOS)-containing cells in the opisthobranch mollusc Aplysia californica was studied by using NADPH-diaphorase (NADPH-d) histochemistry in the CNS and peripheral organs. Chemosensory areas (the mouth area, rhinophores, and tentacles) express the most intense staining, primarily in the form of peripheral highly packed neuropil regions with a glomerular appearance as well as in epithelial sensory-like cells. These epithelial NADPH-d-reactive cells were small and had multiple apical ciliated processes exposed to the environment. NADPH-d processes were also found in the salivary glands, but there was no or very little staining in the buccal mass and foot musculature. In the CNS, most NADPH-d reactivity was associated with the neuropil of the cerebral ganglia, with the highest density of glomeruli-like NADPH-d-reactive neurites in the areas of the termini and around F and C clusters. A few NADPH-d-reactive neurons were also found in other central ganglia, including paired neurons in the buccal, pedal, and pleural ganglia and a few asymmetrical neurons in the abdominal ganglion. The distribution patterns of NADPH-d-reactive neurons did not overlap with other known neurotransmitter systems. The highly selective NADPH-d labeling revealed here suggests the presence of NOS in sensory areas both in the CNS and the peripheral organs of Aplysia and implies a role for NO as a modulator of chemosensory processing. J. Comp. Neurol. 495:10,20, 2006. © 2006 Wiley-Liss, Inc. [source] Differential dye coupling reveals lateral giant escape circuit in crayfishTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2003Brian L. Antonsen Abstract The lateral giant (LG) escape circuit of crayfish mediates a coordinated escape triggered by strong attack to the abdomen. The LG circuit is one of the best understood of small systems, but models of the circuit have mostly been limited to simple ball-and-stick representations, which ignore anatomical details of contacts between circuit elements. Many of the these contacts are electrical; here we use differential dye coupling, a technique which could help reveal connection patterns in many neural circuits, to reveal in detail the circuit within the terminal abdominal ganglion. Sensory input from the tailfan forms a somatotopic map on the projecting LG dendrites, which together with interafferent coupling mediates a lateral excitatory network that selectively amplifies strong, phasic, converging input to LG. Mechanosensory interneurons contact LG at sites distinct from the primary afferents and so maximize their summated effect on LG. Motor neurons and premotor interneurons are excited near the initial segments of the LGs and innervate muscles for generating uropod flaring and telson flexion. Previous research has shown that spatial patterns of input are important for signal integration in LG; this map of electrical contact points will help us to understand synaptic processing in this system. J. Comp. Neurol. 466:1,13, 2003. © 2003 Wiley-Liss, Inc. [source] Quantitative analyses of anatomical and electrotonic structures of local spiking interneurons by three-dimensional morphometry in crayfishTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2001Ryou Hikosaka Abstract We quantitatively investigated the three-dimensional structure of the dendrites of local spiking interneurons using a confocal laser scanning microscope in the terminal abdominal ganglion of crayfish. We also studied their passive membrane properties electrophysiologically using the single-electrode current clamp techniques to analyze their electrotonic structure. All of the local spiking interneurons examined in this study lacked distinctive axonal structure and had a monopolar cell body that was connected with a fine primary process to a thick main segment. Numerous fine secondary processes projected from the main segment in the ganglionic neuropile. The average anatomical length of a secondary process from the main segment to its terminal was 261.9 ± 15.2 ,m. The average input resistance and membrane time constant of local spiking interneurons, obtained from their voltage responses to intracellular injection of step current pulses in the main segment, were 15.2 ± 1.6 M, and 13.9 ± 1.9 msec, respectively. Calculation of the electrotonic length of dendritic processes based on morphological and physiological data obtained in this study revealed that the average electrotonic length of secondary processes in local spiking interneurons was significantly longer than in local nonspiking interneurons, although both types of local interneurons showed apparently similar anaxonic structure. The steady-state voltage attenuation factors for the secondary processes of local spiking interneurons were significantly greater than those of local nonspiking interneurons in both centrifugal and centripetal directions. The larger electrotonic structure of local spiking interneurons compared to that of nonspiking interneurons appears to be compensated for by their excitable dendritic membrane. J. Comp. Neurol. 432:269,284, 2001. © 2001 Wiley-Liss, Inc. [source] | ||||||||||