The macro- and microdistribution and polymorphic electroencephalographic effects of 9 -tetrahydrocannabinol in the rat.

Abstract

The electroencephalographic (EEG) changes in a number of cortical and subcortical structures in the rat following intraperitoneal injection of 4 mg/kg THC was found to be characterized, in most animals, by a biphasic alternation between slow and fast frequencies. Using this shift in frequency as a criterion for altering physiological processes, rats were sacrificed following injections of tritiated THC. Autoradiographic techniques and scintillation counts were used to determine the distribution of THC in the nervous system and several non-neural tissues. In addition to the localization of the drug, the degree of bonding between the drug and tissue was determined by varying chasing procedures which displaced the labelled THC differentially as a function of tissue incorporation. The results indicated that approximately 0.80% of the total THC injected produced the EEG changes observed, and only 0.19% became lipophilically bound. In the nervous system, the drug appeared to be localized primarily in grey matter and deposited extensively in the extra-pyramidal motor system and some limbic structures. Non-neural organs which had extensive deposits included the liver, spleen, and kidney.