Influence of serotonin on the kinetics of vesicular release.
The mechanisms by which synaptic vesicles are transported and primed to fuse with the presynaptic membrane are important to all chemical synapses. Processes of signal transduction that affect vesicular dynamics, such as the second-messenger cascades induced by neuromodulators, are more readily addressed in assessable synaptic preparations of neuromuscular junctions in the crayfish. We assessed the effects of serotonin (5-HT) through the analysis of the latency jitter and the quantal parameters: n and p in the opener muscle of the walking leg in crayfish. There is an increase in the size of the postsynaptic currents due to more vesicles being released. Quantal analysis reveals a presynaptic mechanism by an increase in the number of vesicles being released. Latency measures show more events occur with a short latency in the presence of 5-HT. No effect on the frequency or size of spontaneous release was detected. Thus, the influence of 5-HT is presynaptic, leading to a release of more vesicles at a faster rate.
Southard
R C
RC
Department of Biology, 101 Morgan Building, University of Kentucky, 40506-0225, Lexington, KY, USA.
Haggard
J
J
Crider
M E
ME
Whiteheart
S W
SW
Cooper
R L
RL
D000818:Animals; D003400:Astacoidea; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D018485:Muscle Fibers, Skeletal; D018482:Muscle, Skeletal / Q000294:innervation*; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology*; D011789:Quantum Theory; D011930:Reaction Time; D015290:Second Messenger Systems; D012701:Serotonin / Q000494:pharmacology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000502:physiology
D012701:Serotonin