Influence of the target on distribution and functioning of the varicosities of Helix pomatia metacerebral cell C1 in dissociated cell culture

doi:10.1016/S0306-4522(00)00015-4

Neuroscience

Volume 96, Issue 4, March 2000, Pages 843-853

https://doi.org/10.1016/S0306-4522(00)00015-4 Get rights and content

Abstract

The serotonergic metacerebral giant cell (C1) of Helix pomatia was isolated with its bifurcate axon and plated in culture under five conditions: (i) with no target; (ii) with the appropriate target B2 near the stump of the bigger branch (CBC); (iii) with B2 near the stump of the smaller branch (CC); (iv) with a wrong target (C3) near the stump of the CBC branch and (v) with B2 and C3 positioned near the CBC and CC stump, respectively. The counting of anti-serotonin antibody-labelled varicosities of the C1 neuron showed that the presence of the appropriate target in either axonal domain both down-regulated the number of varicosities of the contralateral neuritic field, and increased their average size, whereas the wrong target induced an overall reduction of the number of C1 neuron varicosities, and inhibited the evoked transmitter release. The action potential-evoked calcium concentration increase in the neuritic terminals of the C1 neuron cultured alone, or in presence of the appropriate target, reached a value significantly higher than that reached in presence of the wrong target.

These results provide evidence that the postsynaptic neuron regulates both morphological and functional development of presynaptic terminals.

Section snippets

Cell culture procedures

Helix neuronal cells were isolated, maintained in culture and tested for chemical connection as previously described.²¹ Briefly, buccal and cerebral ganglia were taken from 2–5-g snails bred at a farm of Helix Breeders National Association, Lanzo (Turin), Italy, and transferred to a proteolytic enzyme solution. After several rinsings, the ganglia were pinned out on a Sylgard-coated dish and desheathed. The C1 and the C3 neurons from the cerebral ganglion and the B2 (middle cell) from the buccal

The two neuritic domains of C1 showed a different number of varicosities

When the command neuron C1 was plated alone, its two separated branches developed an extensive network of neurites within four to five days (Fig. 1A). The processes originate almost exclusively from the two stumps. As in Aplysia MGC,⁴³ the two Helix C1 stumps differed in their diameter, CBC being larger (9.8±0.2 μm) than the CC branch (5.0±0.5 μm, n=10, P<0.001, Student's t-test). The difference in axon size was reflected in the differential distribution of the putative varicosities between the

Discussion

There are two important problems to be discussed. First, we must ask why the number of varicosities of one branch is selectively reduced when the target is contacting the other branch. Second, we must ask why the inappropriate target down-regulates the total number of varicosities of the presynaptic neuron C1 as well as inhibiting the transmitter release.

In absence of the target, the number of varicosities of CBC neurites is greater than that of the CC domain (ratio 1.77). This difference is

Conclusion

The presented findings indicate that two branches of a single neuron modulate the number of their varicosities as a result of the target interaction at one branch. The newly formed neurite domain which is not in contact with the postsynaptic cell decreases the number of releasing sites. The presence of the target increases the average size of the presynaptic varicosities. In the absence of the target, the presynaptic domain is endowed of a great amount of small size varicosities, however

Acknowledgements

The authors are very grateful to L. Milano, C. Franchino and A. Naretto for technical assistance, to Drs A. Casson and J. Hoskins for language revision and to Drs F. Cavallo, and G. Migliaretti for statistic analysis. Helix pomatia at juvenile stage were kindly provided by Mr N. Griglione (A.N.E). This work was supported by grants from MURST and CNR to P.G.M. The financial support of Telethon-Italy (grant 1101) to P.G.M. is also acknowledged.

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Influence of the target on distribution and functioning of the varicosities of Helix pomatia metacerebral cell C1 in dissociated cell culture

Abstract

Section snippets

Cell culture procedures

The two neuritic domains of C1 showed a different number of varicosities

Discussion

Conclusion

Acknowledgements

J. Physiol., Paris

Neuron

Curr. Opin. Neurobiol.

Neuron

Neuron

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Devl Biol.

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Neuron

Brain Res.

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Science

Routing of transmitter and other changes in fast axonal transport after transection of one branch of the bifurcate axon of an identified neuron

J. Neurosci.

Axonal transport of synapsin I-like proteins in rabbit retinal ganglion cells

J. Neurosci.

Optical analysis of synaptic vesicle recycling at frog neuromuscular junction

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Axonal transport of synapsin I and cholinergic synaptic vesicle-like material: further immunohistochemical evidence for transport of axonal cholinergic transmitter vesicle in motor neurons

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Pre-synaptic elements formed on poly-lysine-coated beads contain synaptic vesicle antigens

J. Neurocytol.

Nociceptive inputs to C3, a motoneurone of the tentacle withdrawal reflex in Helix aspersa

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Nature

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