적출 백서 연수후각 신경세포에 미치는 아미노산 신경전달물질과 GABA성 약물의 영향

Effects of amino acids and some drugs related to gaba receptors on the neuronal activity in isolated medullary dorsal horn of rat

This study was performed to elucidate the effects of glutamate, aspartate, substance P and GABAergics on the intracellular membrane potential and membrane input resistance of isolated medullary dorsal horn, and the interrelations between EAA, substance P and GABA in medullary dorsal horn. Transectional slices of caudal part of trigeminal sensory nucleus were prepared from rats about 5 weeks old, then transferred and fixed in the recording chamber where it was preincubated and continuously perfused with airated modified Krebs-Ringer solution. Intracellular recordings were carried out with glass microelectrode to record the changes of membrane potential and membrane resistance induced by perfusion of glutamate, aspartate, substance P, GABA, baclofen and/or bicuculline. Results obtained as follows : 1. Glutamate and aspartate respectively depolarized medullary dorsal horn neurons and decreased membrane input resistance in a dose-dependent manner. Effect of glutamate and aspartate applied simultaneously on medullary dorsal horn neuron was not different from that of glutamate or aspartate, respectively. Substance P also depolarized medullary dorsal horn neurons. 2. Medullary dorsal horn neurons responding to glutamate also responded to aspartate and substance P. 3. GABA and baclofen showed little effects on menbrane potential and input resistance. 4. Bicuculline evoked a depolarization of neurons of medullary dorsal horn.