Abstract
The differential action of neuromodulators on synapses of various efficacy provides additional fine tuning of synaptic regulation beyond frequency induced plasticity. We used the well-characterized high- and low-output motor nerve terminals, of the tonic and phasic neuromuscular junctions (NMJs) in the walking leg extensor muscle of the crayfish, to investigate differential actions of serotonin (5-HT) since both terminals innervate the same target. The excitatory postsynaptic potentials of the tonic NMJ are enhanced to a greater extent than for the phasic NMJs during exposure to 5-HT (100 nM). Macropatch current recordings at identified sites along the motor nerve terminals and quantal analysis indicate that mean quantal content is substantially increased by 5-HT. The overall probability of vesicular release increases to a greater extent at tonic terminals than at phasic terminals when exposed to 100 nM 5-HT. Measures in the area (i.e. charge) of spontaneous quantal currents indicate no difference in postsynaptic receptivity to the glutamatergic synaptic transmission upon exposure to 5-HT. The results provide new details concerning differential modulation of low- and high-output synapses present on the same target tissue.
Original language | English |
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Pages (from-to) | 163-172 |
Number of pages | 10 |
Journal | Neuroscience Research |
Volume | 45 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1 2003 |
Bibliographical note
Funding Information:Appreciation is given to Hye Won Cooper for illustrative work. Support was provided by a Ribble Fellowship and an Interdepartamental Neuroscience Program training fellowship, University of Kentucky, Department of Biology (J.S.) and NSF grants IBN-9808631, ILI DUE-9850907 and IBN-0131459 (R.L.C.).
Keywords
- Crayfish
- Neuromuscular junction
- Neurotransmission
- Serotonin
- Synapse
ASJC Scopus subject areas
- Neuroscience (all)