Interaction of estrogen and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with hepatic fatty acid synthesis and metabolism of male chickens (Gallus domesticus).

This study tested the hypothesis that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) antagonizes estrogen-induced hepatic lipid synthesis and metabolism in birds. Twenty immature male chickens (Gallus domesticus) were divided evenly into four groups: (1) vehicle control; (2) estrogen alone (1.0 mg/kg estradiol cypionate injected on three consecutive days); (3) TCDD alone (50 microg/kg injected on the fourth day); and (4) a combination of the estrogen and TCDD treatments. On day 14, liver samples were collected for quantitative fatty acid analysis by capillary gas chromatography. Birds treated with estrogen alone had increased total triacylglyceride concentrations with specific increases in the Delta9 desaturase products 16:1n7, 18:1n7, 18:1n9, and 20:1n9. In addition, estrogen treatment specifically increased 22:6n3 concentrations in both triacylglycerides and phospholipids. However, these increases in Delta9 desaturase products or 22:6n3 did not occur for birds treated with estrogen in combination with TCDD. TCDD and estrogen plus TCDD treatments increased phospholipid concentrations of the diet-derived polyunsaturated fatty acids 18:2n6, 18:3n6, 20:3n6, 18:3n3, and 20:5n3, although only the estrogen plus TCDD group had significantly increased total phospholipids. In cholesterol esters, all three treatments decreased concentrations of total fatty acids, saturated fatty acids, and Delta9 desaturase products compared to the control group.