Lincoln G A
MRC Reproductive Biology Unit, Centre for Reproductive Biology, Edinburgh, UK.
J Reprod Fertil. 1990 Sep;90(1):285-96. doi: 10.1530/jrf.0.0900285.
Seasonal cycles were monitored in groups of wild (mouflon), feral (Soay) and domesticated breeds of sheep (Shetland, Blackface, Herdwick, Norfolk, Wiltshire, Portland, Merino, Soay x Portland and Soay x Merino) living outdoors near Edinburgh (56 degrees N). Changes in the blood plasma concentrations of prolactin and FSH, and growth of the horns and pelage were measured every half calendar month from 1 to 3 years of age. In all breeds there was a clearly defined seasonal cycle in the plasma concentration of prolactin with an 18-66-fold increase in mean values from the nadir in November and December to the peak in May and June. The seasonal increase in prolactin was closely correlated with the seasonal increase in the growth of the horns, both within and between breeds (e.g. time of peak prolactin vs horn growth for 11 breeds, R = 0.62, P less than 0.05). In the mouflon, Soay and some of the domesticated breeds of sheep (Wiltshire, Herdwick and Shetland), the seasonal increase in prolactin was also temporally correlated with the resurgence of growth of the pelage in spring and a conspicuous moult. In the other breeds developed to produce fine wool (e.g. Norfolk, Portland and Merino), there was no clear seasonal change in the pelage and growth continued throughout the year. Comparison between breeds indicated that continuous growth of the pelage was associated with higher plasma prolactin concentrations in winter. The times of the seasonal changes in plasma concentrations of prolactin were not significantly correlated with the corresponding changes in the plasma concentrations of FSH. The overall results are consistent with a role for prolactin related to the growth of the horns and pelage rather than the seasonal cycle in reproduction. The differences between the wild-type and the domesticated breeds in the pelage represent the effect of selective breeding to produce a long fine fleece which has involved changes in both the seasonal pattern of prolactin secretion and the growth characteristics of the hair fibres.
对生活在爱丁堡附近户外（北纬56度）的野生（摩弗伦羊）、野生驯化（索艾羊）和家养品种绵羊（设得兰羊、黑脸羊、赫德威克羊、诺福克羊、威尔特郡羊、波特兰羊、美利奴羊、索艾羊×波特兰羊和索艾羊×美利奴羊）群体的季节性周期进行了监测。在1至3岁期间，每隔半月测量一次催乳素和促卵泡激素的血浆浓度变化以及角和皮毛的生长情况。在所有品种中，催乳素的血浆浓度都有明确的季节性周期，从11月和12月的最低点到5月和6月的峰值，平均值增加了18至66倍。催乳素的季节性增加与角生长的季节性增加在品种内和品种间都密切相关（例如，11个品种的催乳素峰值时间与角生长的关系，R = 0.62，P < 0.05）。在摩弗伦羊、索艾羊和一些家养品种绵羊（威尔特郡羊、赫德威克羊和设得兰羊）中，催乳素的季节性增加在时间上也与春季皮毛生长的复苏和明显的换毛相关。在其他用于生产细羊毛的品种（如诺福克羊、波特兰羊和美利奴羊）中，皮毛没有明显的季节性变化，全年都在持续生长。品种间的比较表明，皮毛的持续生长与冬季较高的血浆催乳素浓度有关。催乳素血浆浓度的季节性变化时间与促卵泡激素血浆浓度的相应变化没有显著相关性。总体结果表明，催乳素与角和皮毛的生长有关，而不是与繁殖的季节性周期有关。野生型和家养品种在皮毛上的差异代表了选择性育种产生长细羊毛的效果，这涉及催乳素分泌的季节性模式和毛纤维生长特征的变化。
