Abstract This study aimed to expand the knowledge of the interactions between prolactin (PRL) and leptin in the ovine mammary gland during pregnancy and lactation; we examined the mRNA expression of prolactin receptor (PRLR), the long form of the leptin receptor (LRb) and suppressor of cytokine signaling (SOCS)-3 in mammary gland biopsies collected on days 60, 90 and 120 of pregnancy and on days 30, 60 and 90 of lactation (n = 6 for each time point), along with the plasma PRL and leptin concentrations. The PRL concentrations were stable throughout pregnancy and increased during lactation. The plasma leptin concentrations were comparable among nonpregnant, early-pregnant, late-pregnant and lactating ewes, but this metric peaked during mid-pregnancy. Expression of PRLR and SOCS-3 in the mammary gland fluctuated during the transition from pregnancy to lactation, and differences in LRb expression occurred during the late stages of lactation. The LRb transcript abundance was approximately 31 times higher in ewes on day 60 of lactation than in early-lactating ewes. Expression of SOCS-3 mRNA in biopsies gradually decreased over the course of pregnancy and reached a minimum value during late pregnancy. After lambing, the transcript level of SOCS-3 increased and peaked on day 60 of lactation. During pregnancy, the plasma PRL concentration positively correlated with the abundances of PRLR (r = 0.971, P<0.01) and SOCS-3 (r = 0.818, P<0.05). Positive correlations were also observed between the transcript abundances of SOCS-3 and LRb (r = 0.854, P<0.05). The variations observed in the plasma PRL and leptin concentrations and the changes in expression of key leptin and PRL signal transduction pathway components, such as PRLR, LRb and SOCS-3, indicate that the efficacies of both hormone actions are modulated in a multilevel manner throughout pregnancy and lactation. These interactions may regulate the ability of the mammary gland to respond to current energy requirements and challenges, thus affecting milk yield and lactation duration.

中文翻译：

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妊娠和哺乳期间绵羊乳腺中催乳素受体、瘦素受体及其主要抑制因子的转录丰度

摘要 本研究旨在扩大对妊娠和哺乳期间绵羊乳腺中催乳素（PRL）和瘦素相互作用的认识；我们检查了在怀孕第 60、90 和 120 天以及第 30 天收集的乳腺活检中催乳素受体 (PRLR)、瘦素受体 (LRb) 的长形式和细胞因子信号传导抑制因子 (SOCS)-3 的 mRNA 表达、 60 和 90 的哺乳期（每个时间点 n = 6），以及血浆 PRL 和瘦素浓度。PRL 浓度在整个怀孕期间保持稳定，并在哺乳期间增加。非妊娠母羊、早孕母羊、晚孕母羊和哺乳母羊的血浆瘦素浓度相当，但该指标在妊娠中期达到峰值。PRLR 和 SOCS-3 在乳腺中的表达在从妊娠到哺乳的过渡期间出现波动，并且在哺乳后期出现 LRb 表达的差异。哺乳第 60 天的母羊的 LRb 转录本丰度比哺乳早期的母羊高约 31 倍。活检组织中 SOCS-3 mRNA 的表达在妊娠过程中逐渐降低，并在妊娠晚期达到最小值。产羔后，SOCS-3 的转录水平增加并在泌乳第 60 天达到峰值。妊娠期血浆PRL浓度与PRLR（r=0.971，P<0.01）和SOCS-3（r=0.818，P<0.05）丰度呈正相关。在 SOCS-3 和 LRb 的转录本丰度之间也观察到正相关（r = 0.854，P < 0.05）。观察到的血浆 PRL 和瘦素浓度的变化以及关键瘦素和 PRL 信号转导途径组分（如 PRLR、LRb 和 SOCS-3）表达的变化表明，这两种激素作用的功效在整个过程中以多​​级方式受到调节。怀孕和哺乳期。这些相互作用可能会调节乳腺对当前能量需求和挑战的反应能力，从而影响产奶量和泌乳持续时间。