An autosomal recessive condition (rhcjthc) in our closed colony of New Zealand White rabbits (Uaz:NZW-the) results in nonfatal, behavioral convulsions following intravenous (Lv.) injections of delta-9-tetrahydrocannabinol (THC) and other psychoactive cannabinoids of marijuana. The ontogeny of the convulsive response was evaluated in potential THC-seizure-susceptible ( S S ) rabbits from postnatal Days (PN) 15-548. Ages of nonsusceptibility (PN 15-23), partial susceptibility (PN 24-38), and complete susceptibility (PN 39-548) were found. Also, open-field activity was determined in PN 14-25 THC-SS and THC-seizure-resistant (SR) rabbits. Administration of THC during the seizure-insensitive period resulted in genotype-dependent alternations in photocell activity and sprawling.
Our closed breeding colony at the University of Arizona (Uaz:NZW-thc) contains 2 populations of rabbits that are differentiated by their behavioral responses after administration of delta-9-tetrahydrocannabinol (THC). The major psychoactive ingredient of marijuana, THC, is primarily responsible for the production of the constellation of subjective mental alterations in humans which is usually described as a "high." The intravenous (i.v.) administration of THC to rabbits of 1 group produces locomotor stimulation, ataxia and/or behavioral sedation, depending on dose and environmental adaptation . The other rabbit population exhibits nonfatal, behavioral convulsions when given even low doses of THC. Behavioral components of the convulsion consistently include clonus, thrashing, forelimb and hindlimb extensions, and may include ventral flexion of the head (headtuck), and extreme mydriasis and nystagmus (Consroe & Fish, 1980a). In THC-seizure-susceptible (SS) rabbits, the convulsive behaviors are due to genetic factors, in that the phenotype is inherited as the homozygous expression of a single autosomal, recessive gene (thc) with full penetrance and without sex-hkage or -limitation .
Other cannabinoids of marijuana that are reported to be psychoactive in humans also result in behavioral convulsions in the THC-SS rabbits (Consroe & Fish, 1981). Numerous other correlates of THC-SS rabbit convulsions and human psychoactivity have been established. These include dose-response effects of THC, dose-comparability of THC effects,