Hunter M G, Denning-Kendall P, Boulton M I, De Rensis F, Wild M L, Foxcroft G R
AFRC Research Group on Hormones and Farm Animal Reproduction, University of Nottingham, Faculty of Agricultural and Food Sciences, Loughborough, Leics., UK.
J Reprod Fertil. 1992 Jan;94(1):121-8. doi: 10.1530/jrf.0.0940121.
After parturition, eight sows were zero weaned by removing all piglets 6 h after birth; a further 18 sows suckled at least ten piglets each. Blood samples were collected on Day 4 after zero weaning or on Days 4, 14 and 21 of lactation and the sampling frequency increased during suckling bouts. Ovaries were recovered from sows on these days and corpora lutea were either extracted for estimation of relaxin and progesterone concentration, fixed for immunohistochemical analysis or incubated in vitro in the presence or absence of luteinizing hormone (LH) or oxytocin. Luteal weight and progesterone were higher in the zero-weaned sows than in lactating sows (P less than 0.05 and less than 0.001, respectively); relaxin content was below detection by Day 14. This was supported by immunohistochemical staining for relaxin, which showed limited immunostaining in zero-weaned and Day 4 sows, but none in the tissue recovered on Days 14 and 21, which showed typical signs of regression. Secretion of progesterone and relaxin by luteal tissue in vitro was highest in zero-weaned sows (P less than 0.05), decreased as lactation progressed and neither LH nor oxytocin had any significant effect. Concentrations of plasma relaxin were all less than 0.2 ng/ml in three of the four zero-weaned and Day-4-suckled sows assayed; there was no detectable increase during suckling bouts. It was concluded that during lactation the old corpus luteum of pregnancy is not able to release relaxin in response to suckling in vivo or to oxytocin treatment in vitro.
分娩后，8头母猪在产后6小时通过移走所有仔猪进行零断奶；另外18头母猪每头至少哺育10头仔猪。在零断奶后第4天或泌乳期的第4、14和21天采集血样，且在哺乳期间采样频率增加。在这些日子从母猪体内取出卵巢，黄体要么被提取用于测定松弛素和孕酮浓度，要么被固定用于免疫组织化学分析，要么在有或没有促黄体生成素（LH）或催产素存在的情况下进行体外培养。零断奶母猪的黄体重量和孕酮水平高于哺乳母猪（分别P<0.05和P<0.001）；到第14天时松弛素含量低于检测水平。这得到了松弛素免疫组织化学染色的支持，该染色显示零断奶母猪和第4天的母猪免疫染色有限，但在第14天和第21天取出的显示退化典型迹象的组织中没有染色。零断奶母猪的黄体组织体外孕酮和松弛素分泌最高（P<0.05），随着泌乳进展而下降，LH和催产素均无显著影响。在检测的4头零断奶和第4天哺乳的母猪中，有3头血浆松弛素浓度均低于0.2 ng/ml；在哺乳期间没有检测到增加。得出的结论是，在泌乳期间，妊娠的旧黄体在体内不能对哺乳产生反应而释放松弛素，在体外也不能对催产素处理产生反应而释放松弛素。
