Effect of polychlorinated biphenyls (Aroclor-1248) on the secretory function of bovine luteal cells affected by LH, noradrenaline and high density lipoproteins

The corpus luteum (CL), formed from the ruptured follicle, is required for the course of normal cyclicity and the duration of pregnancy in females. The influence of a mixture of polychlorinated biphenyls - PCBs (Aroclor-1248) - on the secretory function of CL (dispersed bovine luteal cells) during different stages of the estrous cycle was studied. The cells (1.2 × 105/ml) were pre-incubated for 24 h and were then treated with 10, 100 or 500 ng/ml of PCBs. Aခ1E;er 24, 48, 72, 96 or 144 h luteinizing hormone (LH; 100 ng/ml; positive control) was added to the medium. The most evident impaired secretion of progesterone was measured after 72 h of incubation with PCBs and this time was selected for the further experiments. In Exp. 2 high density lipoproteins (HDL), as a source of cholesterol (25 μg), increased progesterone secretion from luteal cells; PCBs enhanced this effect in mid and late stage of the estrous cycle. PCBs had no effect on the stimulatory influence of LH, which itself stimulated progesterone secretion. In Exp. 3 PCBs (500 ng/ml) decreased progesterone secretion from the early CL and increased stimulatory effect of noradrenaline (NA) on progesterone secretion from mid CL. Aroclor-1248 stimulated oxytocin (OT) secretion from all stages of CL development. NA alone increased OT secretion from mid and late CL and moreover, it amplified effect by Aroclor on CL from all studied stages of their development. We conclude that the mixture of PCBs, commercially available as Aroclor-1248, can directly impair the function of bovine CL and thus it can affect the estrous cycle duration or embryo development.