Selection of transmitter responses at sites of neurite contact during synapse formation between identified leech neurons.
AUTOR(ES)
Ching, S
RESUMO
1. Pressure sensitive (P) neurons of the leech Hirudo medicinalis show both an inhibitory, Cl(-)-dependent response and a depolarizing, cationic response to pipette application of serotonin (5-HT). Serotonergic Retzius (R) neurons in culture reform inhibitory, Cl(-)-dependent synapses with P neurons but fail to elicit the extrasynaptic, depolarizing response to 5-HT. We have examined the localization of the selection of 5-HT responses by testing the sensitivity of P cell growth cones and neurites to 5-HT application. 2. As measured by intracellular recording at the P cell soma, synaptic release of 5-HT from R cell processes activated only the Cl(-)-dependent response in P cell neurites. Focal application of 5-HT from a micropipette depolarized uncontacted P cell growth cones and neurites. In contrast, processes from the same P cells that were contacted by R cells were rarely depolarized by 5-HT application unless the application pipette was moved along the neurites away from the sites of contact. 3. The channels underlying the depolarizing response to 5-HT were identified in patch clamp recordings from P cell growth cones. These cation channels showed rare, brief openings in the absence of 5-HT. Application of 5-HT in the bath (outside the patch pipette) increased channel activity in uncontacted P cell growth cones but not in growth cones of the same P cells contacted by R cells. 4. We conclude that the selection of transmitter responses during synapse formation was localized to discrete sites of contact between the synaptic partners.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1143835Documentos Relacionados
- Tyrosine phosphorylation during synapse formation between identified leech neurons.
- Voltage dependence of 5-hydroxytryptamine release at a synapse between identified leech neurones in culture.
- The role of 5-hydroxytryptamine as a transmitter between identified leech neurones in culture.
- Lithium Increases Synapse Formation between Hippocampal Neurons by Depleting PhosphoinositidesS⃞
- Inhibition of Ca2+ conductance in identified leech neurons by benzodiazepines.