Alterations of T cell distribution and functions in prenatally cypermethrin-exposed rats: possible involvement of catecholamines

The synthetic pyrethroid insecticide, cypermethrin (50 mg/Kg) was given dur ing gestation to pregnant rats by gavage in corn oil. Prenatal cypermethrin -exposure induces a marked and long-lasting increase of adrenaline (A) and noradrenaline (NA) plasma concentrations. The enhancement of plasma catecho lamine levels was accompanied by a marked increase of CD5(+), CD4(+), and C D8(+) total T cell numbers in the peripheral blood, while in the spleen a r eduction of all T cell subsets was observed. In addition, peripheral blood lymphocytes (PBL) from rats prenatally exposed to cypermethrin showed an en hanced capability to proliferate in response to different doses of Concanav alin A (ConA), or human recombinant interleukin-2 (hrIL-2), whereas an impa ired proliferative response was observed in the spleen. The percent increas e of NA, but not A plasma concentrations paralleles the immunomodulatory ef fects induced by cypermethrin neonatal exposure on T cell distribution and mitogen-induced proliferation in the peripheral blood and spleen. Collectiv ely, our results suggest that the changes in mitogen-induced proliferative responses in the peripheral blood and spleen of prenatally cypermethrin-exp osed rats may be attributable to pesticide-induced catecholamine release, w hich causes an increased output of CD5(+), CD4(+), and CD8(+) T cells from the spleen to the peripheral blood, and a consequent lymphocytosis. (C) 199 9 Elsevier Science Ireland Ltd. All rights reserved.