CYPERMETHRIN-INDUCED ALTERATION OF THYMOCYTE DISTRIBUTION AND FUNCTIONS IN PRENATALLY-EXPOSED RATS

The synthetic pyrethroid insecticide, cypermethrin (50 mg/kg) vias giv en during gestation to pregnant rats by gavage in corn oil. Prenatal c ypermethrin exposure induced a significant decrease in the absolute nu mber of all thymocyte subsets during the first 30 days after birth, be ing the double negative CD4(-)CD8(-), single positive CD4 and CD8 T ce lls preferentially affected, Later on day 60 and 90 double positive CD 4(+)CD8(+) and single positive thymocytes gradually recovered, while t he total number of CD4(-)CD8(-) cells was increased. Moreover, thymocy tes from rats prenatally exposed to cypermethrin showed an impaired ab ility to proliferate in response to different doses of Concanavalin A (ConA) and human recombinant interleukin-2 (hrIL-2) and to produce and /or release IL-2. Overall, our results indicate that cypermethrin admi nistered during prenatal period can affect multiple steps in thymocyte differentiation pathways resulting in an altered cell subset distribu tion and an impairment of thymocyte functions. (C) 1998 Elsevier Scien ce Ireland Ltd. All rights reserved.