Effects of delta 9-tetrahydrocannabinol on sensory-evoked discharges of granule cells in the dentate gyrus of behaving rats.
Extracellular action potentials were recorded from identified cells in the dentate gyrus of the awake freely moving rat during performance of a two-tone discrimination task. The effects of low doses of delta 9-tetrahydrocannabinol (delta 9-THC) were assessed on the firing patterns of granule cells to the tone stimuli. Intraperitoneal injections of delta 9-THC at 1.0 and 2.0 mg/kg, but not 0.5 mg/kg, produced a significant suppression of granule cell activity lasting up to 4 hr. This suppression was present in both the spontaneous (pretone) activity and tone-evoked responses of granule cells. The tone responses of cells recorded from the inferior colliculus were unaffected by THC injection at 1.0 and 2.0 mg/kg, implicating further the hippocampus as a site of specific action of delta 9-THC. In the preceding paper it was demonstrated that such doses produced both impairment of discrimination behavior and modifications of sensory-evoked potentials recorded from the dentate gyrus. However, the influence of delta 9-THC on cell firing in the dentate gyrus was more severe both in magnitude and duration of suppression than were the effects on behavior and on sensory-evoked potentials.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D013759:Dronabinol / Q000494:pharmacology*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D013759:Dronabinol