Cypermethrin-induced alteration of thymocyte distribution and functions in prenatally-exposed rats.

The synthetic pyrethroid insecticide, cypermethrin (50 mg/kg) was given during gestation to pregnant rats by gavage in corn oil. Prenatal cypermethrin exposure induced a significant decrease in the absolute number of all thymocyte subsets during the first 30 days after birth, being the double negative CD4-CD8-, single positive CD4 and CD8 T cells preferentially affected. Later on day 60 and 90 double positive CD4+CD8+ and single positive thymocytes gradually recovered, while the total number of CD4 CD8 cells was increased. Moreover, thymocytes from rats prenatally exposed to cypermethrin showed an impaired ability 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 administered during prenatal period can affect multiple steps in thymocyte differentiation pathways resulting in an altered cell subset distribution and an impairment of thymocyte functions.