Effects of Δ⁹-thc on the synaptosomal uptake of 3h-tryptophan and³h-choline

The in vitro addition of (-)-Δ⁹-tetrahydrocannabinol (Δ⁹-THC) resulted in a dose- responsive inhibition of the high-affinity specific synaptosomal uptake of both³H-tryptophan and³H-choline in mouse forebrain crude synaptosomal preparations. The approximate concentrations of Δ⁹-THC required to cause a 50% inhibition of the uptake of³H-tryptophan and³H-choline were 33 and 16 µM, respectively. Kinetic analysis showed that inhibition of both compounds were consistent with a noncompetitive mechanism. The pretreatment of mice with doses of 10, 30 or 100 mg/kg Δ⁹-THC had no effect on the subsequent in vitro synaptosomal uptake of either 3H-tryptophan or³H-choline into forebrain synaptosomes.