Farmer C, Sorensen M T, Petitclerc D
Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Centre, Lennoxville, Québec.
J Anim Sci. 2000 May;78(5):1303-9. doi: 10.2527/2000.7851303x.
Prolactin is required for mammary development in various species but its possible role for mammogenesis in pigs is not known. The goal of the present study was therefore to determine the effect of prolactin inhibition by bromocriptine during the last third of gestation on mammary gland development in gilts. Twenty-eight primigravid gilts were assigned as controls (n = 15) or received 10 mg of bromocriptine orally thrice daily (n = 13) from d 70 to 110 of gestation. Jugular blood samples were collected on d 70 of gestation and every 8 d thereafter and were assayed for prolactin, IGF-I, estradiol, and progesterone. Gilts were slaughtered on d 110 of gestation and fetuses were counted and weighed. One row of mammary glands was used for dissection of parenchymal and extraparenchymal tissues and for determination of DNA, RNA, dry matter, protein, and fat contents. Tissue from the other row was used for measures of prolactin receptor number and affinity. Concentrations of prolactin were drastically reduced throughout the bromocriptine treatment period (P < .001), whereas there was no overall treatment effect on progesterone and IGF-I levels (P > .10). Total weight and extraparenchymal tissue weight of the mammary glands were unaffected by treatment (P > or = .1), but weight of parenchymal tissue, total DNA, and total RNA decreased (P < .01) with bromocriptine treatment. Percentages of fat and dry matter in parenchymal tissue increased with bromocriptine treatment (P < .01) and the percentage of protein decreased (P < .01). Number of prolactin receptors in parenchymal tissue decreased with bromocriptine treatment (P < .001) and receptor affinity increased (P < .001). Average fetal weight was lower in gilts receiving bromocriptine than in control gilts (P = .05), but fetal number did not differ (P > .1). These results clearly demonstrate that prolactin is essential for normal mammary gland development and can affect fetal growth during the last third of gestation in gilts.
催乳素在多种物种的乳腺发育中是必需的，但它在猪乳腺生成中的可能作用尚不清楚。因此，本研究的目的是确定在妊娠最后三分之一期间用溴隐亭抑制催乳素对后备母猪乳腺发育的影响。28头初产后备母猪被分配为对照组（n = 15）或从妊娠第70天至110天每天口服3次10毫克溴隐亭（n = 13）。在妊娠第70天及此后每8天采集颈静脉血样，检测催乳素、胰岛素样生长因子-I（IGF-I）、雌二醇和孕酮。在妊娠第110天屠宰后备母猪，统计并称重胎儿。一排乳腺用于解剖实质和实质外组织，并测定DNA、RNA、干物质、蛋白质和脂肪含量。另一排的组织用于测量催乳素受体数量和亲和力。在整个溴隐亭治疗期间，催乳素浓度大幅降低（P < 0.001），而对孕酮和IGF-I水平没有总体治疗效果（P > 0.10）。乳腺的总重量和实质外组织重量不受治疗影响（P ≥ 0.1），但溴隐亭治疗使实质组织重量、总DNA和总RNA减少（P < 0.01）。溴隐亭治疗使实质组织中的脂肪和干物质百分比增加（P < 0.01），蛋白质百分比降低（P < 0.01）
