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Different putative neuromodulators are present in the nerves which
distribute to the teleost skeletal muscle
G. Radaelli1, C. Domeneghini,2 S. Arrighi2, F. Mascarello1,
A. Veggetti3
1Department of Animal Sciences, Faculty of Veterinary Medicine,
University of Padova, 2Institute of Domestic Animal Anatomy, Faculty of
Veterinary Medicine, University of Milano, 3Department of Veterinary Morphophysiology
and Animal Production, Faculty of Veterinary Medicine, University of Bologna,
Italy
Offprint requests to: Prof.
Cinzia Domeneghini, Istituto di Anatomia degli Animali Domestici, Via Celoria,
10, I-20133 Milano, Italy. Fax: 02.2367788
Summary. The presence of putative
neuromodulators in the nerve fibres was investigated in white skeletal muscle
of two teleost fish not taxonomically correlated and showing different patterns
of innervation (multiple versus focal innervation). Cryostat sections of
epaxial, hypaxial and adductor mandibulae (AM) muscles of Sparus aurata
and Anguilla anguilla were stained histochemically for reduced nicotinamide
adenine dinucleotide phosphate (NADPH)-diaphorase. Other sections were used
for indirect immunohistochemistry (streptavidin-biotin and rhodamine immunofluorescence
methods), employing antibodies specific for putative excitatory or inhibitory
peptides, including CGRP, substance P, met-enkephalin, bombesin, and VIP.
In addition, ultrastructural observations were performed in order to describe
the morphology of the motor endplates. A strong immunoreactivity for CGRP
and substance P was found in many nerve terminals. Met-enkephalin, bombesin
and VIP immunoreactivities were less frequently observed. No immunoreactivity
was observed to CCK, NPY or 5-HT. NADPH-diaphorase was identified in nerve
fibres of the AM complex only of A. anguilla. Electron microscopy observations
evidenced more than one type of synaptic vesicle in motor endplates. Some
differences in putative neuromodulator distributions were observed in the
two species and muscle complexes, which may be related to the different
taxonomical position as well as the different pattern of innervation of
white muscle fibres. Histol. Histopathol. 13, 939-947 (1998)
Key words: Teleosts, skeletal
muscle, neuropeptides, NOS.
DOI: 10.14670/HH-13.939
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