@article {2452, title = {Neural network partitioning by NO and cGMP.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {21}, year = {2001}, month = {2001 Mar 1}, pages = {1610-8}, abstract = {

The stomatogastric ganglion (STG) of the crab Cancer productus contains approximately 30 neurons arrayed into two different networks (gastric mill and pyloric), each of which produces a distinct motor pattern in vitro. Here we show that the functional division of the STG into these two networks requires intact NO-cGMP signaling. Multiple nitric oxide synthase (NOS)-like proteins are expressed in the stomatogastric nervous system, and NO appears to be released as an orthograde transmitter from descending inputs to the STG. The receptor of NO, a soluble guanylate cyclase (sGC), is expressed in a subset of neurons in both motor networks. When NO diffusion or sGC activation are blocked within the ganglion, the two networks combine into a single conjoint circuit. The gastric mill motor rhythm breaks down, and several gastric neurons pattern switch and begin firing in pyloric time. The functional reorganization of the STG is both rapid and reversible, and the gastric mill motor rhythm is restored when the ganglion is returned to normal saline. Finally, pharmacological manipulations of the NO-cGMP pathway are ineffective when descending modulatory inputs to the STG are blocked. This suggests that the NO-cGMP pathway may interact with other biochemical cascades to partition rhythmic motor output from the ganglion.

}, keywords = {Animals, Arginine, Brachyura, Citrulline, Cyclic GMP, Digestive System, Enzyme Inhibitors, Fluorescent Dyes, Ganglia, Guanylate Cyclase, Immunohistochemistry, Invertebrate, Isoquinolines, Male, Nerve Net, Neurons, Neurotransmitter Agents, Nitric Oxide, Nitric Oxide Donors, Periodicity, Signal Transduction}, issn = {1529-2401}, author = {Scholz, N L and de Vente, J and Truman, J W and Graubard, K} } @article {2460, title = {Nitric oxide-sensitive guanylate cyclase activity is associated with the maturational phase of neuronal development in insects.}, journal = {Development}, volume = {122}, year = {1996}, month = {1996 Dec}, pages = {3949-58}, abstract = {

Many developing insect neurones pass through a phase when they respond to nitric oxide (NO) by producing cyclic GMP. Studies on identified grasshopper motoneurones show that this NO sensitivity appears after the growth cone has arrived at its target but before it has started to send out branches. NO sensitivity typically ends as synaptogenesis is nearing completion. Data from interneurones and sensory neurones are also consistent with the hypothesis that NO sensitivity appears as a developing neurone changes from axonal outgrowth to maturation and synaptogenesis. Cyclic GMP likely constitutes part of a retrograde signalling pathway between a neurone and its synaptic partner. NO sensitivity also appears in some mature neurones at times when they may be undergoing synaptic rearrangement. Comparative studies on other insects indicate that the association between an NO-sensitive guanylate cyclase and synaptogenesis is an ancient one, as evidenced by its presence in both ancient and more recently evolved insect groups.

}, keywords = {Afferent, Animals, Cyclic GMP, Dihydrolipoamide Dehydrogenase, Drosophila melanogaster, Grasshoppers, Guanylate Cyclase, Insects, Interneurons, Motor Neurons, Nervous System, Neurons, Nitric Oxide, Nitroprusside, Phylogeny}, issn = {0950-1991}, author = {Truman, J W and de Vente, J and Ball, E E} } @article {2461, title = {Neuropeptide induction of cyclic GMP increases in the insect CNS: resolution at the level of single identifiable neurons.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {14}, year = {1994}, month = {1994 Dec}, pages = {7704-12}, abstract = {

In insects, the neuropeptide eclosion hormone (EH) acts on the CNS to evoke the stereotyped behaviors that cause ecdysis, the shedding of the cuticle at the end of each molt. Concomitantly, EH induces an increase in cyclic GMP (cGMP). Using antibodies against this second messenger, we show that this increase is confined to a network of 50 peptidergic neurons distributed throughout the CNS. Increases appeared 30 min after EH treatment, spread rapidly throughout these neurons, and were extremely long lived. We show that this response is synaptically driven, and does not involve the soluble, nitric oxide (NO)-activated, guanylate cyclase. Stereotyped variations in the duration of the cGMP response among neurons suggest a role in coordinating responses having different latencies and durations.

}, keywords = {Animals, Central Nervous System, Cyclic GMP, Enzyme Activation, Guanylate Cyclase, Immunohistochemistry, Insect Hormones, Manduca, Neurons, Synapses, Time Factors}, issn = {0270-6474}, author = {Ewer, J and de Vente, J and Truman, J W} }