CYTOARCHITECTONIC AND NEUROCHEMICAL PROPERTIES OF SPINAL CORD IN TELEOST FISHES
E. V. Puschina,1 A. A. Varaksin,1 G. G. Kalinina 2
1 Institute of Marine Biology, Far East Branch of RAS, and 2 Far Eastern State Technical
Fisheries University, Department of Aquaculture, Vladivostok;
e-mail: puschina@mail.ru
Traditional neuromorphological and NADPH-diaphorase methods were used to study the topography, morphology
and neurochemical organization properties of spinal cord in teleosts fishes. The heterogeneous population
of NO-producing motoneurons was revealed in the motor column of spinal cords from studied species. Dendrites
of primary motoneurons formed rich plexus at the spinal segment periphery. This morphological pattern is
determined by translational motion of the fishes in the water (trunk-tail movement), and has no connection with
the origin of upper and lower extremities. The NO-producing capacity of spinal motoneurons shows their connection
with premotor NO-ergic brain system, including over situated motor centers of reticular formation and
descending projections of giant steam neurons (Mauthner and Muller cells). The NO-producing Rohon-Berd neurons
were found in the dorso-medial part of spinal cord from studied fishes. These cells with the ascending propriospinal
targets form spinal nociceptive system. Thus, the sense Rohon-Berd cells and most motor neurons of
studied bony fishes are nitric oxide synthesizing ones. Spinal cord NO-synthesizing territories are situated in
concordance with dorso-ventral histochemical gradient. Spinal cord interneurons of these fishes produce nitric
oxide selectively. The quantity of NO-synthesizing reticular cells is determined by two main factors: the connection
with the specialized neurochemical complexes, where NO is a specific neuromodulator, and individual
properties of spinal cord structure directed by conditions of morphoadaptation.
Key words: teleosts fishes, NADPH-diaphorase, spinal cord, motoneuron, Rohon-Berd neurons,
nociception, propriospinal targets
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