Impact of pollution in neurosecretory cells of ganglia nerves of Molluscan Mytilidae: Approach of the neuroendocrine control
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1
University Mohammed V- Agdal, Laboratory of Biological Rhythms and Environment, Faculty of Science, Morocco
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2
Ibn Zohr University, Laboratory of Aquatic Ecosystems: Marine and Continental Field, Department of Biology, Faculty of Science, Morocco
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3
Faculty of Sciences Semlalia, Department of Biology, Pharmacology, Neurobiology and Behaviour laboratory, Morocco
Histological and immunocytochemical investigations on the gonads and nerve ganglia of the African mussel: Perna perna, were carried out i) to follow the seasonal variations of the storage tissue during the sexual cycle of the mollusc and ii) to determine to determine the quantitative variations of neurosecretory cells (NSCs) in the nerve ganglia during the different phases of the sexual cycle. Studies were performed in two mussel populations, the first living in an unpolluted site (Cap Ghir) and the other in an area contaminated with domestic and industrial wastewater (Anza).
The number of NSCs, determinate by topographic staining (paraldehyde thionine, or Azan by Roméï’s method) was significantly correlated with the sexual cycle and the reserve cycle. Two phases in increasing number of NSCs were observed in the two types of ganglia studied (cerebroid, and pedal ganglia) as well as in both mussel populations. The first (from December to June) preceded gonial mitoses and spawning, while the storage tissue decreased in volume. The second period (from July to November) was characterized by a greater increase in NSC numbers: it preceded a new gametogenetic wave and coincided with reconstitution of the storage tissue. However, at Anza, this second period was preceded by the development of the storage tissue which remained large up to the numerical decrease of NSCs.
In Cap Ghir mussels, the (Gonadotropin-releasing hormone) GnRH-positive NSCs in the cerebroid and pedal ganglia showed the same development in relation to the different phases of the sexual cycle and the storage tissue. However, they were more numerous in the cerebroid than in the pedal ganglia. The number of GnRH-immunoreactive NSCs peaked in December in the cerebroid ganglia and this process preceded sexual maturation and spawning, whereas the lowest numbers were observed during sexual rest. However, during acinar development and the beginning of vitellogenesis, the positive CNS increased in numbers. In the same sampling site, the insuline-positive NSCs present in both types of ganglia did not have the same development from December to July: in the cerebroid ganglia, the number of these cells decreased, while the pedal ganglia contained twice more NSCs during reserve reconstitution. In contrast, during the second period, the increase of insuline-like NSCs was greater in the cerebroid ganglia, whereas the storage tissue decreased to its minimum.
Compared to Cap Ghir, the numbers of immunoreactive NSCs noted at Anza inversely evolved. If high numbers of GnRH-positive NSCs in the cerebroid ganglia were noted during the sexual cycle, such values were only found in the pedal ganglia during spawning, while the numbers of these cells were low in the latter ganglia during gamete lysis. The number of insuline-positive NSCs in the cerebroid ganglia steadily increased during the sexual cycle in spite of variations in this last cycle and the storage tissue. In contrast, in the pedal ganglia, the number of these positive cells did not change during storage tissue regression and increased when the tissue was reconstitute. The quantitative evolution of the NSCs showed a significant correlation with the sexual cycle and that of the reserves. It is likely that the products of secretion of the NSCs act on the target cells, of the gonad, the GnRH-like act on sexual cells, while Insuline-like would act on storage cells of Bivalve Mollusks.
Conference:
2nd NEUROMED Workshop, Fez, Morocco, 10 Jun - 12 Jun, 2010.
Presentation Type:
Poster Presentation
Topic:
Poster session 1: Neurodegenerative diseases
Citation:
Benomar
S,
Aarab
L,
Klouche
M,
Moukrim
A,
Lakhdar-Ghazal
NY and
Mathieu
M
(2010). Impact of pollution in neurosecretory cells of ganglia nerves of Molluscan Mytilidae: Approach of the neuroendocrine control.
Front. Neurosci.
Conference Abstract:
2nd NEUROMED Workshop.
doi: 10.3389/conf.fnins.2010.12.00014
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Received:
03 Jun 2010;
Published Online:
03 Jun 2010.
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Correspondence:
S. Benomar, University Mohammed V- Agdal, Laboratory of Biological Rhythms and Environment, Faculty of Science, Rabat, Morocco, sbenomar@fsr.ac.ma