Effect of melatonin on the monodeiodinase activity in skin of Cashmere Goats | 外源褪黑激素对绒山羊皮肤脱碘酶活性的影响

chinois. 探讨褪黑激素(MT)促进山羊绒毛生长的机理。选择16只(15±1)月龄、平均体质量(33.1±2.9) kg、产绒量相近的内蒙古白绒山羊羯羊，随机分为2组，其中1组每隔2个月皮下埋植1次MT（2 mg/kg），共埋植3次，另1组作为对照组不埋植MT；所有试验羊均在相同时间采集血样和皮样，分别用于激素浓度和脱碘酶（MD）活性测定。与对照组相比，MT埋植组绒山羊血浆MT质量浓度差异显著(P＜0.01)；羊绒生长速度在7和8月极显著高于对照组(P＜0.01)，在9月显著高于对照组(P＜0.05)。7、8月份MT埋植组绒山羊皮肤组织中的MDⅡ活性水平明显高于对照组(P＜0.05)；MT埋植组MDⅢ与MDⅡ活性的比值在7、8月份显著低于对照组(P＜0.05)，表明MT在调控皮肤脱碘酶(MD)活性上有重要作用。MT埋植后2个月内能够刺激羊绒生长，这可能是通过改变皮肤组织中的MD活性来实现的。

anglais. The study was made to reveal the cashmere proven mechanism of melatonin (MT), which can promote the growth of cashmere fiber. Sixteen half-sib Inner Mongolia cashmere weathers were allocated randomly to two groups (n=8/group). One group was implanted subcutaneously with the melatonin implants (2 mg/kg BW) while another group was not implanted as the control group. Blood sample and the dermatoid were gathered at the same time to determine the hormone density and the MD activeness separately. The results showed the plasma melatonin concentration presented significant differences (P＜0.01) between the implant group (M) and the control group (C). The cashmere fiber growth rate of the M was higher than that of the C in July (P＜0.01) and August (P＜0.001). During July and August, the monodeiodinase type Ⅱ (MDⅡ) activity for the M group was higher (P＜0.05) than that of the C group. The ratio of the monodeiodinase typeⅢ (MDⅢ) and MDⅡ for the M group was lower (P＜0.05) than that of the C group in July and August. The results demonstrated that melatonin plays an important role in the regulation of skin MD activity. Simultaneously the melatonin stimulated cashmere fiber elongation, which may result from enhanced MDⅡactivity after melatonin treatment.