Concanavalin A alters synaptic specificity between cultured Aplysia neurons.

Factors that regulate synaptic specificity were investigated with Aplysia buccal and bag cell neurons in primary cell culture. In the presence of fetal calf serum electrical synapses are formed between buccal-buccal or bag-bag cell pairs, but not between buccal-bag cell pairs. Instead, buccal neurons make inhibitory chemical synapses on bag cells. However, in the presence of nanomolar concentrations of the lectin concanavalin A this pattern changes, such that more than 75 percent of buccal-bag pairs exhibit electrical synapses and the frequency of occurrence of buccal-bag chemical synapses is reduced. Such changes in synaptic specificity may be important in determining the types of synapses formed during neuronal development and neurite regeneration.