THE EFFECTS OF SOME DRUGS ON AN EVOKED RESPONSE SENSITIVE TO TETRAHYDROCANNABINOLS

¹ Department of Pharmacology and Toxicology, University of Rochester, School of Medicine and Dentistry, Rochester, New York

The effects of several drugs were compared with those of ⁹-tetrahydrocannabinol (⁹-THC) on responses evoked in frontal lobe polysensory areas, ipsi- and contralateral to the stimulus site in primary somatosensory cortex, in squirrel monkeys with postmesencephalic or high spinal sections. ⁹-THC augmented both the earlyd evoked response and the late evoked response, which occurs 150 to 200 msec after the stimulus. It also frequently augmented or induced repetitive synchronous activity after the late response. In contrast, pentobarbital, ethanol and diethyl ether depressed both early and late responses, while chlorpromazine and chloralose depressed late responses without consistently affecting early responses; none of these drugs induced late repetitive activity. Mescaline had effects similar to those of ⁹-THC on late responses, but its effect on early responses was much less. Lysergic acid diethylamide had little effect on early responses but depressed late responses at high doses. Phencyclidine also had little effect on early responses. It facilitated late responses at low doses and depressed them at high doses. Picrotoxin and pentylenetetrazol had effects similar to, but greater than, those of ⁹-THC. Strychnine had variable, and mostly small, effects on evoked responses. Gallamine, atropine, amphetamine, levarterenol and methoxamine were essentially without effect on the responses studied. It is concluded that the effects of ⁹-THC and mescaline on these responses in polysensory cortex are similar to those of certain convulsants but are unlike those of depressants or of amphetamine, levarterenol, lysergic acid diethylamide, phencyclidine or strychnine.