Phagocytosis of the protozoon Tetrahymena pyriformis as an endpoint in the estimation of cocaine salt and cocaine freebase toxicity

Abstract

Cells of the ciliated protozoon Tetrahymena pyriformis strain W, grown in a peptone-yeast medium, usually contain many phagocytic vacuoles. The phagocytic activity of this protozoon was studied in vivo using heat-inactivated yeast stained with carmine after exposing the cultures for 1 hour to different doses of cocaine hydrochloride or cocaine freebase (crack) (0.5, 1 or 2 mg/100 ml of protozoan culture).The number of vacuoles formed indicated the phagocytic activity. Cocaine hydrochloride and crack caused a decrease of the phagocytic activity of the protozoon (p < 0.05) when compared to the control cultures. Furthermore, the two chemical forms of cocaine, salt and free-base respectively, caused quantitatively different effects on the phagocytic activity. Crack produced an extensive decrease in phagocytosis, compared to equal concentrations of cocaine hydrochloride. These results suggest a possible relationship between cocaine abuse and the suppression of phagocytosis that may contribute to the impairment of immunity in drug misusers.

DNA Toxicity of Cocaine Hydrochloride and Cocaine Freebase by Means of DNA Image Analysis on Tetrahymena pyriformis.

“…This effect might be related to the faster onset of action due to the higher lipophilicity of the freebase, speculation that is in agreement with the literature. 7,8,12) Furthermore, the reduction of DNA content observed during the second hour of the experiment, might represent a direct cytotoxic effect after a prolonged exposure of the cultures to the drug. 7,23,24) According to previous experiments of ours with the protozoan phagocytosis, 12) cocaine salt and freebase present a quantitatively different behavior on Tetrahymena cultures.…”

“…18,19) This protozoan was grown axenically in a proteose-peptone broth at 25°C, without stirring the cultures, until reaching late log phase, generally 4-5 d after inoculation. 12) Cocaine hydrochloride or crack was added to the 100-ml cultures as aqueous solution in doses 1 and 2 mg of substance per 100 ml of culture respectively. These doses were selected based on previous studies carried out in our laboratory with doses ranging from 0.15 to 0.60 mg of both cocaine and crack per ml of protozoan culture, which did not produce any effects.…”

“…21) We did not extend our experiments to higher doses, since we focused on concentrations similar to those found in human blood. 20) For each drug and dose selected 12,20) one protozoan culture was tested and another culture served as control. The cultures were allowed to stand for either 1 or 2 h after administration of the substances.…”

“…For each drug and dose selected 12,20) one protozoan culture was tested and another culture served as control. The cultures were allowed to stand for either 1 or 2 h after administration of the substances.…”

“…7,8) The protozoan Tetrahymena pyriformis, a monocellular organism, is a suitable experimental model for functional, pharmacological, toxicological or immunotoxic studies. [9][10][11][12] Our experience with this protozoan has led us to consider its DNA content as a parameter that we could examine for the detection of toxic responses to cocaine. This protozoan contains a macronucleus which participates in the conjugation and division of the cell and contains deoxyribonucleic acid.…”