Effects of mimosine administered to a perfused area of skin in Angora goats

The effect of mimosine on a perfused area of skin tissue was studied using an isolated perfusion technique. Four mature Angora wethers (body weight 35 kg, SE 2.3) were cannulated bilaterally with indwelling silicon catheters in the superficial branches of the deep circumflex iliac artery and vein. Mimosine (40 mg/kg BW0.75/d) was infused intraarterially into one iliac artery of each goat for 3 d and saline was infused in the contralateral (control) iliac artery. Iliac venous blood samples were taken from both sides along with arterial samples from the carotid artery. Mimosine infusion elevated plasma mimosine in the carotid artery (52.6, SEM 19.21) and iliac vein on the saline treated side to 54.1 M (SEM 16.31) and in the iliac vein on the mimosine treated side to 191.3 M (SEM 19.14; P<0.01). Mimosine decreased feed intake (2.3 vs 0.6 kg/d, SEM 0.29; P<0.001) and water consumption (5.2 vs 1.3 L/d, SEM 0.67; P<0.001). Mimosine did not cause defleecing in the area of infusion and was cleared from the bloodstream within 12 h of cessation of infusion. The following effects were also observed during mimosine infusion: decrease in plasma amino acids to half pre-infusion values (methionine 22.7 vs 13.1 M, SEM 1.41; lysine 95.9 v. 37.4 M, SEM 4.28; P<0.001), decrease in plasma T3 (149.5 vs 69.5 ng/dL, SEM 4.31; P<0.001), T4 (6.15 vs 1.95 g/dL, SEM 0.18; P<0.001) and insulin 28.7 vs 17.3 IU/ml, SEM 1.89; P<0.01), increase in plasma cortisol (1.4 vs 6.2 g/dL, SEM 0.35; P<0.001); decrease in plasma zinc and magnesium (0.97 vs 0.49 mg/L, SEM 0.063; P<0.001 and 21.4 vs 14.6 mg/L, SEM 1.74; P<0.001, respectively). All reported parameters returned to their normal values 24 h after cessation of mimosine infusion except feed intake which was affected for a longer period. Mohair length and diameter were not affected by mimosine infusion. The toxicity of mimosine may be due to the drastic depletion of zinc and magnesium in the blood as mimosine possesses very strong chelating properties and is excreted in the urine as a chelate.