Role of very low density lipoproteins in the accumulation of o, p′-DDT in fish ovaries during gonadal recrudescence

Abstract

The binding of o, p′-DDT by plasma lipoproteins and its accumulation in the gonads of Atlantic croaker ( Micropogonias undulatus) were investigated. Tissue accumulation of o, p′-DDT was determined in fish fed o, p′-DDT for a 3 week period during gonadal recrudescence at concentrations of 1.8, 10.8, and 54.6 μg o, p′-DDT per 100 g fish day −1. The ovaries accumulated significantly more o, p′-DDT than the testes at the three dosage levels ( P < 0.001). Furthermore, there was a positive linear correlation between the size of the ovaries, as calculated by the gonadosomatic index, and their o, p′-DDT content ( r 2 = 0.52, 0.85, and 0.76 for the low, middle and high doses, respectively). Compartmentalization of o, p′-DDT within the oocyte occurred, with over 95% of the o, p′-DDT present in the triglyceride-rich oil globule. The triglyceride-rich, very low density lipoprotein (VLDL) fraction of the plasma contained the highest percentage of o, p′-DDT (40%) with little (less than 7%) in the vitellogenin-containing VHDL. In addition, ovarian uptake of o, p′-DDT when it was bound to VLDL was six times greater than that observed after injection of o, p′-DDT bound to vitellogenin or in corn oil. The results suggest that o, p′-DDT is carried in the plasma via lipoproteins and that oocyte uptake of triglyceride-rich VLDL is a major mechanism of o, p′-DDT accumulation in croaker ovaries.