caa a22 4500 463254848 CHVBK 20180405153351.0 cr unu---uuuuu 170326e20070201xx s 000 0 eng 10.1007/s10571-006-9091-3 doi (NATIONALLICENCE)springer-10.1007/s10571-006-9091-3 Characterization of NO/cGMP-Mediated Responses in Identified Motoneurons [Elektronische Daten] [Ricardo Zayas, Barry Trimmer] 1. Nitric oxide (NO) is thought to play a neuromodulatory role in the nervous system of vertebrate and invertebrate species. In the hornworm Manduca sexta, NO-mediated signaling has been implicated in behavioral and developmental processes, but its exact function in neurons is unknown. In this study, we identify specific neurons in the CNS of Manduca larvae that accumulate cGMP in response to treatment with NO donors in the presence of cGMP-phosphodiesterase inhibitors. Subsets of these neurons were identified as motoneuron-12 (MN12) and intersegmental motoneurons (ISMs), which innervate dorsal oblique muscles of the larvae. 2. To investigate the physiological role of NO-evoked increases in cGMP in these motoneurons we performed intracellular recordings; we found that application of NO donors caused an increase in neuronal excitability that was characterized by an increase in the spontaneous firing frequency. When action potentials and EPSPs were blocked, NO treatment evoked a depolarization of the resting membrane potential and a decrease in the measured input resistance in both MN12 and the ISMs. 3. Additional experiments with MN12 showed that treatment with the cGMP analogue, 8-Br-cGMP mimicked the NO effect on the resting potential and the input resistance. Furthermore, MN12 incubation with the NOS inhibitor, L-NNA, resulted in a small hyperpolarization of the resting potential and an increase in the input resistance, and incubation with the sGC inhibitor, ODQ blocked the NO-evoked depolarization of MN12. Finally, NO treatment during voltage clamping of MN12 evoked an inward positive current. 4. Taken together, these results suggest that NO can act as a "gain control” of neuronal excitability, which might have an important role in insect behavior. Springer Science+Business Media, Inc., 2006 nitric oxide nationallicence phosphodiesterase inhibitors nationallicence soluble guanylyl cyclase nationallicence insect nationallicence manduca nationallicence Zayas Ricardo Department of Biology, Dana Laboratory, Tufts University, 02155, Medford, MA, USA aut Trimmer Barry Department of Biology, Dana Laboratory, Tufts University, 02155, Medford, MA, USA aut Cellular and Molecular Neurobiology Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 27/2(2007-02-01), 191-209 0272-4340 27:2<191 2007 27 10571 https://doi.org/10.1007/s10571-006-9091-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10571-006-9091-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zayas Ricardo Department of Biology, Dana Laboratory, Tufts University, 02155, Medford, MA, USA aut NATIONALLICENCE 700 1- Trimmer Barry Department of Biology, Dana Laboratory, Tufts University, 02155, Medford, MA, USA aut NATIONALLICENCE 773 0- Cellular and Molecular Neurobiology Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 27/2(2007-02-01), 191-209 0272-4340 27:2<191 2007 27 10571 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer