PHARMACOLOGIC DEFINITION OF NEURONAL COMPONENTS GENERATING SPONTANEOUS AND EVOKED POTENTIALS IN THE TECTUM OF THE CHICK: EFFECT OF -HYDROXYBUTYRATE

¹ Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis, California

The effect of -hydroxybutyrate (GOHBA) on bioelectric potentials recorded from the avian tectum is a marked depression of spontaneous potential oscillations. The photically evoked response in the tectum is altered so that the rise-time of the first negative spike is increased while the overall response amplitude is enhanced. The action of GOHBA on spontaneous activity is similar to that seen with high doses of pentobarbital but is more specific in that the latter also severely depresses the evoked response. -Aminobutynic acid (GABA) and GOHBA exert diametrically opposite actions on both types of bioelectric potentials. It is concluded that despite certain similarities between GOHBA and barbiturates, the former drug is sufficiently unique in its action on central nervous system activity to warrant separate pharmacodynamic classification. In addition, a variety of evidence is presented suggesting that GOHBA action is at the synaptic level. An attempt is made to explain its mode of action on the basis of specific drug reactivity on different anatomical sites of the synapse in question, with these affected sites playing different physiologic roles in the genesis of spontaneous and evoked electrical activity.