ODOR, DRUG AND TOXIN ANALYSIS WITH NEURONAL NETWORKS IN-VITRO - EXTRACELLULAR ARRAY RECORDING OF NETWORK RESPONSES

Neurons, by virtue of intrinsic electrophysiological mechanisms, repre sent transducers that report the dynamics of cell death, receptor-liga nd interactions, alterations in metabolism and generic membrane perfor ation processes. In cell culture, mammalian neurons form fault-toleran t, spontaneously active systems with great sensitivity to their chemic al environment and generate response profiles that are often concentra tion- and substance-specific. Changes in action potential patterns are usually detected before morphological changes and cell damage occur, which provides sensitivity and reversibility. Such biological systems can be used to screen rapidly for novel pharmacological substances, to xic agents, and for the detection of certain odorants. Existing simple culture preparations can already be employed effectively for the dete ction of chemical compounds. So far, three strategies have been invest igated in pilot experiments: (1) Substance-dependent major changes in spontaneous native activity patterns. All synaptically active agents ( e.g. glutamate, strychnine, N-methyl D-aspartic acid) as well as metab olic poisons generate such changes. (2) Substance-dependent changes in network oscillations via disinhibition. The regularized, oscillatory activity is altered by synaptically and metabolically active substance s, ion channel blockers, and toxins. (3) Detection of paroxysmal respo nses indicating major, pathological membrane currents in large subpopu lation of cells. We have explored these three strategies via 64 channe l array recordings using spontaneously active murine spinal cord cultu res. The glycine receptor blocker strychnine reliably generated increa sed multichannel bursting at 5-20 nM and regular, coordinated bursting above 5 mu M. During biculline-induced network oscillations many comp ounds alter oscillation frequencies or terminate activity in a substan ce-specific manner. Finally, the gp120 protein of the AIDS virus (at 1 mu g/ml) produces massive, unique paroxysmal discharges that may last as long as 2 min. These results indicate that cultured neuronal netwo rks are practical systems that can be used for the detection and ident ification of a great variety of chemical substances. The concept of dy namic fingerprinting to identify specific compounds is discussed. (C) 1997 Published by Elsevier Science Limited.