Effect of temperature on synaptic transmission between identified neurones of the mollusc Lymnaea stagnalis.

The mollusc, Lymnaea stagnalis, has been used as a model to study the mechanisms of temperature-dependent processes in the central nervous system. Effects of temperature changes on transmission in monosynaptic connections, made by the FMRFamide-containing neurone VD4 and the giant dopaminergic neurone RPeD1 with follower neurones, were recorded with intracellular microelectrodes. In the temperature range of 4-6 degrees C, inhibitory postsynaptic potentials (IPSP) in response to VD4 stimulation were not observed in postsynaptic cells while the IPSPs persisted in the RPeD1 followers. A temperature rise resulted in a sharp increase in the IPSP amplitude in followers of both VD4 and RPeD1. In isolated nervous systems taken from molluscs which have been kept at 4-6 degrees C for 2 weeks and more, no coupling between VD4, RPeD1 and synaptically connected cells was seen in the full experimental temperature range. The synaptic coupling recovered only after maintaining the molluscs at a water temperature of 14-16 degrees C for at least 2 days. The changes observed in synaptic responses to temperature alterations correspond to the behaviour of the molluscs.