THE CEREBRAL NEURONS OF HELIX-ASPERSA DURING HIBERNATION - CHANGES INTHE CYTOCHEMICAL DETECTION OF CALMODULIN, CYTOSKELETAL COMPONENTS ANDPHOSPHATASES

Citation
C. Vignola et al., THE CEREBRAL NEURONS OF HELIX-ASPERSA DURING HIBERNATION - CHANGES INTHE CYTOCHEMICAL DETECTION OF CALMODULIN, CYTOSKELETAL COMPONENTS ANDPHOSPHATASES, Tissue & cell, 27(2), 1995, pp. 185-196
Citations number
91
Categorie Soggetti
Cell Biology
Journal title
ISSN journal
00408166
Volume
27
Issue
2
Year of publication
1995
Pages
185 - 196
Database
ISI
SICI code
0040-8166(1995)27:2<185:TCNOHD>2.0.ZU;2-W
Abstract
Some markers of the intracellular systems that regulate neuronal activ ity and morphology were analyzed in the cerebral ganglion of hibernati ng snails (Helix aspersa), in comparison with active animals. The immu nocytochemical expression of a calcium-binding protein, i.e. calmoduli n, and some cytoskeletal components, i.e. 200 kDa phosphorylated neuro filament protein (pNFH), microtubule associated protein 2 (MAP2) and a lpha-tubulin were analyzed by the use of a panel of antibodies raised against mammal antigens. Moreover, by enzymatic reactions the Ca2+-ATP ase and alkaline phosphatase (AlPase) activities were demonstrated. In comparison with the active phase, the hibernation induced an increase in the immunopositivity for calmodulin in all the neurons. The increa se may be linked to unmasking of immunoreactive epitopes due to confor mational changes of the protein, which in turn may be a consequence of a reduction or absence of binding with calcium ions or of a veal incr ease in the amount of calmodulin in the somata of neurons. In any even t, both the hypotheses indicate that neurons have decreased or suppres sed the Ca2+-dependent mechanisms as also shown by the lower Ca2+-ATPa se activity. Nevertheless, the AlPase activity, which was localized in the epineural sheat, was not significantly changed during hibernation and this supports that some metabolic activities are preserved in the hibernated animals. Changes in the immunopositivity for cytoskeletal components weve found. There was an increase in the epitopes recognize d by the mammalian pNF antibody, that concerned both the positivity of the entire cytoplasm of some clusters of metacerebral neurons and the intensity of the reaction. This would be aimed to improve the stabili ty of the somata and primary neurites. Moreover, the decrease of alpha -tubulin and MAP2 immunopositivity, suggests that a disassembly of mic rotubules have occurred. The findings indicate that the transport of v esicles in the axons is slowed down during hibernation. In fact, resea rch in progress show that the patterns of neurotransmission and neurom odulation are also deeply modified.