University of Kentucky
Differentially Regulated Pools of Synaptic Vesicles within Motor Nerve Terminals
Institution
University of Kentucky
Faculty Advisor/ Mentor
Robin Cooper
Abstract
When the glutamate-ergic neuromuscular junctions of the crayfish are treated with DL-TBOA (10 µM), a glutamate uptake blocker, excitatory postsynaptic responses (EPSPs) are attenuated in amplitude over time with repeated stimulation. Thus, one would assume the pool of vesicles for release are becoming used up and depleted of glutamate. Recycling of empty vesicles may occur. However, when the EPSPs were very small and the bath is exchanged to TBOA (10 µM) and 5-HT (1 µM), within 1 minute the EPSPs start to appear at random and upon stimulation the evoked EPSPs are very large as compared with the baseline control prior to exposure to TBOA. Thus, when 5-HT is added in the presence of TBOA, a new pool, also referred to as a reserve pool, of vesicles are recruited which have glutamate already packaged in them. This result demonstrates that the electrically excitable pool of vesicles and the 5-HT modulated vesicle pool are divisible within the presynaptic nerve terminal. Currently various stimulation paradigms are being used to measure the kinetics of the electrically excited pool of vesicles.
Differentially Regulated Pools of Synaptic Vesicles within Motor Nerve Terminals
When the glutamate-ergic neuromuscular junctions of the crayfish are treated with DL-TBOA (10 µM), a glutamate uptake blocker, excitatory postsynaptic responses (EPSPs) are attenuated in amplitude over time with repeated stimulation. Thus, one would assume the pool of vesicles for release are becoming used up and depleted of glutamate. Recycling of empty vesicles may occur. However, when the EPSPs were very small and the bath is exchanged to TBOA (10 µM) and 5-HT (1 µM), within 1 minute the EPSPs start to appear at random and upon stimulation the evoked EPSPs are very large as compared with the baseline control prior to exposure to TBOA. Thus, when 5-HT is added in the presence of TBOA, a new pool, also referred to as a reserve pool, of vesicles are recruited which have glutamate already packaged in them. This result demonstrates that the electrically excitable pool of vesicles and the 5-HT modulated vesicle pool are divisible within the presynaptic nerve terminal. Currently various stimulation paradigms are being used to measure the kinetics of the electrically excited pool of vesicles.