| Abstract No.: | C-B3042 |
| Country: | Canada |
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| Title: | DOPAMINE DEPRESSES SYNAPTIC TRANSMISSION BETWEEN THE LYMNAEA STAGNALIS NEURONES VD4 AND LPED1 |
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| Authors/Affiliations: | 1 Louis-Pierre Asselin Jarry*; 1 Naweed Syed;
1 University of Calgary, AB, Canada
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| Content: | This study was designed to examine metaplasticity that occur at a tripartite synapse between cholinergic, serotonergic and dopaminergic neurons from the mollusc Lymanea. Specifically, we sought to determine how dopamine either applied exogenously or via its endogenous synaptic release (from right pedal dorsal 1, RPeD1) may affect the efficacy of synaptic transmission between a cholinergic neuron (visceral dorsal 4, VD4) and its postsynaptic serotonergic partner (left pedal dorsal 1 , LPeD1) paired as triplet in a soma-soma-soma configuration. Individual neurones were selected from the ganglia of animals between 10 and 15 mm in length and cultured in conditioned medium (CM) for a period of 18 to 20 hours. Sharp electrode intracellular recordings were made to measure the changes in potential. To show dopamine’s effects, focal puffs of dopamine (10-5 M) were pressure applied on single VD4 and LPeD1 somata and also at the synapse, as well as the direct release of dopamine through RPeD1 stimulation in a tripartite configuration. Our data show that when paired in a soma-soma configuration, single action potentials in VD4 produce 1:1 excitatory postsynaptic potentials (EPSPs). Moreover, this synapse also exhibited short-term potentiation where bursts of spikes in VD4 resulted in the subsequent enhancement of synaptic transmission between the pairs. Concomitant stimulation of RPeD1 or exogenously applied dopamine depressed the efficacy of synaptic transmission between the VD4-LPeD1 pair. These data will help show the direct effects of one synapse on another acutely or during synaptogenesis; a simple and measurable form of plasticity. This study will further examine the cellular and synaptic mechanisms that underlie dopamine-induced modulatory changes at a tripartite synapse and will propose a potential pathway through which the output of a network may be regulated by neurons embedded within the circuit. |
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