Development of nitrergic neurons in the nervous system of the locust embryo.
We followed the development of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) system during locust embryogenesis in whole mount nervous systems and brain sections by using various cytochemical techniques. We visualized NO-sensitive neurons by cGMP immunofluorescence after incubation with an NO donor in the presence of the soluble guanylyl cyclase (sGC) activator YC-1 and the phosphodiesterase-inhibitor isobutyl-methyl-xanthine (IBMX). Central nervous system (CNS) cells respond to NO as early as 38% embryogenesis. By using the NADPH-diaphorase technique, we identified somata and neurites of possible NO-synthesizing cells in the CNS. The first NADPH-diaphorase-positive cell bodies appear around 40% embryogenesis in the brain and at 47% in the ventral nerve cord. The number of positive cells reaches the full complement of adult cells at 80%. In the brain, some structures, e.g., the mushroom bodies acquire NADPH-diaphorase staining only postembryonically. Immunolocalization of L-citrulline confirmed the presence of NOS in NADPH-diaphorase-stained neurons and, in addition, indicated enzymatic activity in vivo. In whole mount ventral nerve cords, citrulline immunolabeling was present in varying subsets of NADPH-diaphorase-positive cells, but staining was very variable and often weak. However, in a regeneration paradigm in which one of the two connectives between ganglia had been crushed, strong, reliable staining was observed as early as 60% embryogenesis. Thus, citrulline immunolabeling appears to reflect specific activity of NOS. However, in younger embryos, NOS may not always be constitutively active or may be so at a very low level, below the citrulline antibody detection threshold. For the CNS, histochemical markers for NOS do not provide conclusive evidence for a developmental role of this enzyme.
Cell Biology, Institute of Physiology, University of Veterinary Medicine Hannover, D-30173 Hannover, Germany. Michael.stern@tiho-hannover.de
Michael
M
Stern
Nicole
N
Böger
René
R
Eickhoff
Christina
C
Lorbeer
Ulrike
U
Kerssen
Maren
M
Ziegler
Giorgio P
GP
Martinelli
Gay R
GR
Holstein
Gerd
G
Bicker
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000196:embryology; D002956:Citrulline / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D020536:Enzyme Activators / Q000494:pharmacology; D017952:Ganglia, Invertebrate / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D007191:Indazoles / Q000494:pharmacology; D048188:Locusta migratoria / Q000187:drug effects / Q000196:embryology*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009416:Nerve Regeneration; D009420:Nervous System / Q000196:embryology; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D019581:Neuropil / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction
D020536:Enzyme Activators; D007191:Indazoles; D010726:Phosphodiesterase Inhibitors; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D002956:Citrulline; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine