Formation of novel central and peripheral connections between molluscan central neurons in organ cultured ganglia

Abstract

An in vitro organ culture system for buccal ganglia of the adult snail, Helisoma, is described. The system supports: (1) maintenance of characteristic electrophysiological parameters of identified neurons over seven days of culture; (2) choline metabolism including uptake and synthesis over the same duration; (3) sprouting and growth of neurons in response to axotomy; (4) the formation of novel central electrotonic connections between identified neurons as a result of sprouting and growth. These observations on neuronal growth and the formation of connections are similar to those made with in vivo culture. The use of in vitro culture allows precise manipulations not previously possible. When buccal ganglia are cultured in vitro with the cut distal ends of peripheral nerve trunks held closely apposed, axons of neurons 5R and 5L in the nerve trunks are capable of forming electrotonic connections similar to central connections. The capability of these neurons to form electrotonic connections via their peripheral axons implies that special structures (i.e., central neurites) are not required for the formation of connections; and neither are special environments (i.e., the central neuropile) required for these connections.

Regeneration of central and peripheral synaptic connections in the locomotor system of the pteropod molluscClione limacina

“…No unusual electrical connections were found in this study, although they have previously been reported in molluscan ganglia (Cohan et al, 1987;Hadley et al, 1982). These 'incorrect' electrical connections are rather common in culture of the isolated cells (Bodmer et al, 1984;Carrow and Levitan, 1989;Hadley et al, 1983;.…”

“…In some cases new processes of neurons follow the routes of their original axons (motoneuron B15 in Aplysia (Ross et al, 1994), giant serotoninergic cerebral cell in Achatina (Chiasson et al, 1994) and in Helisoma (Murphy et al, 1985)). In other cases the neurons can produce aberrant branches (RPeD1 cell in Lymnaea , buccal neurons in Helisoma (Murphy and Kater, 1980a,b;Bulloch and Kater, 1982;Hadley et al, 1982), motoneurons in cockroach (Denburg, 1982)), although some predominant growth directions were observed. The neurons mentioned above originally grow into peripheral nerves and their behavior is similar to that of motoneurons in Clione.…”

“…Our experiments in Clione with pedal ganglia co-cultured in close contact were similar to those made previously in Helisoma. In Helisoma the cut peripheral nerve trunks from the buccal ganglia were attached by their distal ends (Hadley et al, 1982). The B4 motoneurons formed electrical connections in the region of attached stumps.…”

Transient Electrical Coupling Delays the Onset of Chemical Neurotransmission at Developing Synapses

“…2 A, arrow) can result in the formation of novel interneuronal connections during regeneration (Hadley et al, 1982). The commissure connecting the right and left buccal ganglia contains the axonal processes of many neurons, including those of 19 and 110.…”

“…Neurons from Aplysia (Bodmer et al, 1988;Carrow and Levitan, 1989), Lymnaea (Janse et al, 1986;Hamakawa et al, 1999a,b;Woodin et al, 1999), the leech (Ready and Nicholls, 1979;Nicholls et al, 1990;Fernandez-de-Miguel and Drapeau, 1995;De-Miguel, 2000;Kristan et al, 2001), and our system, Helisoma trivolvis (Hadley et al, 1982(Hadley et al, , 1985Kater, 1985;Zoran et al, 1996;Magoski and Bulloch, 1998) have been used extensively for the study of both electrical and chemical synapse formation between identified neurons in vivo and in cell culture.…”