Effect of estrogen and 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD) on plasma fatty acids of immature male chickens (Gallus domesticus)

This study investigated the effects of 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD) and estrogen on plasma lipids in immature male chickens. Fatty acids were quantified in plasma collected on day 14 from chickens injected with either: Estrogen plus TCDD-1 mg estradiol cypionate /kg body wt. daily for 3 days and 50 microg TCDD/kg body wt. on day 4; Estrogen--1 mg estradiol cypionate/kg body wt. daily for 3 days and vehicle only on day 4; TCDD-vehicle only for 3 days and 50 microg TCDD/kg body wt. on day 4; or Vehicle--same volume of appropriate vehicle for 4 days. TCDD treatment alone increased the plasma concentrations of total triacylglycerides and of the specific fatty acids 14:0, 15:0, 18:0, 18:2n6, 18:3n3, 20:0, 20:1n9, 20:2n6, 20:3n6, 20:5n3 and 22:1n9, compared with vehicle treatment. The concentration of 22:6n3 was increased in all plasma lipid classes of the estrogen group compared with the vehicle group, but was not increased in the estrogen plus TCDD group. Overall, TCDD treatment alone increased plasma lipids, possibly as a result of decreased clearance or utilization; whereas estrogen plus TCDD treatment antagonized estrogen-induced increases in 22:6n3 but did not cause hyperlipidemia.     

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 μg/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 Δ9 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 Δ9 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 Δ9 desaturase products compared to the control group.     

Novel function of the skin in calcium metabolism in female and male chickens (Gallus domesticus)

To study the role of the skin in differential calcium metabolism in White Leghorn chickens, we compared the composition of suction blister fluid (SBF) collected from cutaneous blisters with blood and serum in female and male animals in various physiological states. As an estimate for interstitial fluid (IF), SBF was used as a determinant of local cutaneous metabolism. Sample collection was carried out under ketamine–xylazine anesthesia. Eight chickens of both sexes were raised freely in similar environmental conditions and fed with similar food during their growth from juvenile to sexually mature and fully adult state. SBF, blood and serum were examined for concentrations of ionized Ca²⁺, Na⁺ and K⁺ with ion-selective electrodes (ISEs), and osmolalities by freezing point osmometry. pH and total protein content were also assessed. Our results showed that SBF of chickens is calcium-poor at the juvenile state and that it draws more Ca²⁺ in adult males than laying females of the same age. Interestingly, Ca²⁺ accumulation was observed also in females after laying had ceased. There was a positive correlation between blood and SBF Ca²⁺ in females but a negative one in males. In general, it was found that SBF of chickens was rich in Na⁺ and K⁺, was hypertonic compared to serum at the juvenile state and had a protein content of 36–47% of that in serum. Different from mammals, SBF in adult chickens was alkaline with the mean values of 8.7 ± 0.14 in females and 8.8 ± 0.06 in males. Age- and sex-related variability in cutaneous Ca²⁺ concentrations in chickens, and the differences of SBF composition between that of mammals point to a novel role of skin functions in avians. Possible functions of the skin as a dynamic calcium source balancing the free circulating Ca²⁺ levels and, also, as an excretory organ for Ca²⁺ are discussed.