Action of delta 9-tetrahydrocannabinol on cell division and macromolecular synthesis in division-synchronized protozoa.

Delta 9-Tetrahydrocannabinol (THC) elicited a dose-dependent (3.2-24 muM) response for form/movement, cellular growth and division in log growth phase and division-synchronized Tetrahymena pyriformis GL. Progressive dose-dependent action of THC on division delays in division-synchronized cell cultures was correlated with a concomitant reduction of division maxima and the percent of cells that completed division I. THC depressed the incorporation of 5-3H-uridine, 2-14C-thymidine and L-3-14C-phenylalanine into RNA, DNA and protein macromolecules respectively of division-synchronized Tetrahymena during division I. The depression of incorporation of 5-3H-uridine into nucleic acid macromolecules was correlated with a reduction of exogenous precursor in the cellular pool. The specific activity of radiolabeled mRNA and nascent polypeptides of polyribosomal fractions from synchronized cells was reduced by THC treatment. THC caused an inhibition of the incorporation of 5-3H-uridine into ribosomal RNA (17S and 25S RNA) and ribosomal precursor RNA (35S RNA) of synchronized cells.