NEUROPHYSIOLOGICAL APPROACH AS A TOOL TO STUDY EFFECTS OF DRUGS ON CENTRAL NERVOUS-SYSTEM - DOSE EFFECT OF PENTOBARBITAL

Average sensory evoked responses were recorded simultaneously from the inferior colliculus, mesencephalic reticular formation, nucleus ventralis lateralis thalami, ventromedial hypothalamus, caudate nucleus, and somatosensory cortex of freely behaving rats. Permanent semimicroelectrodes were implanted in target sites several days before experiments were begun. Several doses of pentobarbital were used; the responses observed were related to the dosage of the barbiturate and the time after injection. Effective doses of pentobarbital caused changes in the evoked responses in all animals and in all six structures. Dependable biphasic changes were observed; low doses increased and high doses attenuated the evoked potentials. The degree of attentuation was different between structures. Use of the same techniques and preparation with different drugs demonstrates different patterns of drug-induced alterations, indicating that this technique detects specific effects of drugs on the central nervous system. The role of the reticular formation as the primary site of barbiturate action is discussed. © 1978.