(184f) Rapid Drug Microadministration toward Neuron Using Electrochemical Micropump for Brain Therapy

A brain and sensory organs has very complicated system where each neuron plays its individual role. Therefore rapid microinjection toward identified neuron would produce innovation of therapy of brain or sense organs We are interested in micro-administering toward identified neuron. Although micropumps for delivering chemical stimulant are already on practical use, these experiment tools need complicated mechanics and wiring. We then developed a simple micropump which is able to jet out inner solution rapidly by bubbling resulted from electrolysis of water. The micropump consists of a glass capillary (O.D. 1.5mm) with a tip of 10µm in diameter in which platinum wires were inserted as electrodes. It was filled with neurotransmitter solution and sealed by hotglue. We then designed the micropump as an artificial sensory neuron. We used Aplysia's L7 (motor neuron in Abdominal ganglion) as a model cell which is sensitive to glutamate released from sensory neuron. The micropump, which was filled with 10mM glutamate, was placed close (< 10µm) to L7 axonal branches. A potential difference of 3.0V was applied to the electrodes when administering glutamate. Neuronal potential change of L7 was recorded by conventional electrophysiological measurement. Each glutamate administration generated an Excitatory Post Synaptic Potential (EPSP). EPSP decreased gradually with successive administration. This reduction of EPSP is thought to be due to glutamate receptor's desensitization. Then, this pump worked as a substitution of sensory neuron. This micropump could mimic activities and behavior of sensory neuron. We will be able to develop more downsized and integrated micropump because its structure is very simple. The micropump is feasible for potential tool of therapy of brain or sensory organs.