An in vitro model to evaluate the effect of an organophosphoric agropesticide on cell proliferation in mouse seminiferous tubules.

Recently, there has been public concern about the toxic effects of organophosphoric pesticides (OP) upon human and animal populations. Since the seminiferous epithelium is an actively proliferating tissue, it was of interest to study germ cell proliferation in the isolated seminiferous tubules of mice that were cultured in the presence of Parathion or paraoxon, its metabolite. Eighteen 3-month-old CF-1 male mice were used. Paraoxon (PO) and Parathion (PT) were added to cultures of seminiferous tubules in the following groups: (1) Ham F-10 medium pH 7.4 (M) (control); groups 2 to 5, M + decreasing doses of either PO or PT (0.8; 0.4; 0.04; 0.004; 0.0004 mM). Each group consisted of six mice. Incubation of the tubules was carried out for 5 h at 35 degrees C, 5% CO2, 95% air. One hour before the end of incubation 5 microCi of 3H-thymidine was added to the cultures. DNA uptake was measured by scintillation counting. PO and PT at concentrations of 0.8 mM elicited a sharp decrease in testicular DNA synthesis. Recuperation at concentrations under 0.4 mM was different. With PO it was rapid, possibly due to the high detoxificative ability of the testis, which contains high quantities of the enzyme 'type A esterases' that hydrolyses PO. At concentrations lower than PO, PT has an inhibitory effect upon germ cell proliferation, which deserves further research.