Inhibitory effects of organochlorine pesticides on intercellular transfer of Lucifer Yellow in cultured bovine oviductal cells

The present study investigated the effects of dichlorodiphenyltrichloroetha ne (DDT), methoxychlor (MXC), and gamma-hexachlorocyclohexane (gamma HCH, l indane) on gap junctional intercellular communication (GJIC) in cultured bo vine oviductal cells. GJIC was evaluated by microinjecting fluorescent dye Lucifer Yellow and observing the inhibition of the spreading of dye into ad jacent cells. After incubation for 1 h at 37 degrees C, a dose-dependent in hibition of GJIC was observed over a concentration range of 16 to 128 mu M DDT, MXC, or gamma HCH compared with nonexposed controls. A significant inh ibition began at 32 mu M DDT, MXC, or gamma HCH. After incubation for 5 h, a dose-dependent inhibition of GJIC was obtained in the concentration range from 8 to 64 mu M of the pesticides. The first significant inhibitory effe ct on GJIC was caused by 8 mu M DDT, 16 mu M MXC, and 32 mu M gamma HCH. Th e 128 mu M concentration of the pesticides was toxic. At pesticide concentr ation of 64 mu M, the decrease in dye-coupling observed was not due to leth al cell injury, as is indicated by the use of trypan blue dye exclusion. Af ter removal of 64 mu M DDT from the culture medium, intercellular communica tion was reestablished within 3 h. Measurement of cytosolic free Ca2+ conce ntration [Ca2+](i) in fura-2/AM-loaded oviductal cells showed that the inhi bition of GJIC by addition of DDT, MXC, or gamma HCH was not associated wit h a detectable increase in [Ca2+],. Coincubation of the DDT with dibutyryl- cAMP prevented the 64 mu M DDT-induced inhibition of intercellular communic ation in adherent oviduct cells. It is suggested that organochlorine pestic ides can influence cells responsible for reproduction.