Studies are underway to ascertain information on: (a) acute and chronic effects of cannabidiol (CBD), a nontoxic constituent of marijuana, given alone and in combination with antiepileptic drugs, on experimentally induced seizure models; (b) electroencephalographic (EEG) and behavioral effects of cannabinol (CBN); and (c) effects of acute and chronic administration of delta 9 THC, CBN and CBD, and their interactions, in marijuana cannabinoid-seizure susceptible rabbits. The acute anticonvulsant effects of CBD and antiepileptic drugs (phenytoin; phenobarbital; etc.) will be studied in minimal and maximal audiogenic seizure models: similar effects will be ascertained following chronic (e.g., 14 day) administration of these drugs, given singly and in combination. It is anticipated that these studies will provide important predictive information on the potential therapeutic spectrum of CBD and basic information on mechanisms and interactive effects of this major marijuana constituent. Quantitative EEG and behavioral effects of CBD, a naturally occurring marijuana cannabinoid that has some psychoactive effects in man, will be studied in normal rabbits. Additionally the acute and chronic effects of delta 9 THC, CBN, and CBD, and their interactions, will be studied in our novel strain of marijuana cannabinoid seizure-susceptible rabbits. It is anticipated that these studies will help to define structure-activity and mechanistic information of marijuana cannabinoids and further characterize the development of potentially novel paradigms of psychoactive cannabinoid action.