JOHNSTONE, A.; BRAILOIU, E.; COOPER, R.L.; Dept. of Biology, Univ. KY.; Dept Pharmacol., E. TN State Univ.; Dept. of Biology, Univ. KY.: Alteration in synaptic transmission at the neuromuscular junction in crayfish, Drosophila and frog by exogenous application of the second messenger, IP6.

The inositol IP3 is well established as a modulator of synaptic transmission, however other inositol metabolites, such as IP6, are also becoming known to have a role. Since IP6 has been shown to have a plasmalemmal binding site on neurons, our goal was to comparatively examine IP6’s role at the crayfish, Drosophila and frog neuromuscular junction (NMJ) for possible effects on synaptic function. Preliminary results reveal that IP6 (10 microM) applied exogenously at the crayfish NMJ results in an enhancement of the excitatory postsynaptic potentials, possible by enhancing transmitter release. However no significant change was observed in facilitation. At frog NMJ IP6 increases in concentration-dependent manner (10, 50, 100 microM) the spontaneous transmitter release also implying a presynaptic action. Studies are currently underway at the Drosophila NMJ and the results will be reported on the poster at the meeting. Funded by NSF grants IBN-9808631, ILI-DUE9850907, and IBN- 0131459 (RLC).