Meeting Abstract
P3.110 Saturday, Jan. 5 The Regulation of Synaptic Vesicle Pools Within Motor Nerve Terminals LEE, J.Y.*; CHUNG, W.Y.; LOGSDON, S.; JOHNSTONE, A. F. M. ; COOPER, R.L.; Dept of Biology, Univ of KY & Army, Daejun, Republic of Korea; Dept. of Chem., Korea Military Academy, Seoul, Republic of Korea; Dept of Biol., Univ of KY; Dept of Biol., Univ of KY; Dept of Biol., Univ of KY, Lexington, KY, USA 40506 RLCOOP1@email.uky.edu
There are populations of vesicles within nerve terminals that behave differently in their fusion and recycling kinetics. We make use of the known simplicity of the synaptic structure at the crayfish opener neuromuscular junction (NMJ) and its quantal nature of transmitter release to assess discrete synapses within the motor nerve terminals. With physiological and pharmacological means we set out to address if the uptake of synaptically released glutamate is important in the refilling of the readily releasable pool of vesicles that rapidly recycles during maintained stimulation. Reserve pools of vesicles can be recruited, by the use of serotonin (5-HT), while the RRP remains reduced functionally. In the presence of TBOA, the presynaptic glutamate uptake blocker, with repeated stimulation the synaptic responses (EPSPs) attenuate in amplitude. Thus, the pool of evoked vesicles for release might not be depleted, but they are recycling with little or no glutamate present. However, 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. We are now investigating the reserve pool and rapid recycling pool with blocking vesicle uptake of glutamate to compare with effects of TBOA alone or in addition to blocking vesicle uptake. In this study, we have demonstrated that within a presynaptic motor nerve terminal of the crayfish NMJ the RP and the RRP of vesicles are distinguishable in their recycling paths during electrical activity of the terminals. Funding:NSF-IBN-0131459 (RLC), Univ. KY (JYL), Korean Army & Korea Military Academy (JYL & WYC).
