Dodd S C, Forsyth I A, Buttle H L, Gurr M I, Dils R R
Endocrinology and Animal Physiology Department, Institute for Grassland and Animal Production, Hurley, Maidenhead, UK.
J Dairy Res. 1994 Feb;61(1):35-45. doi: 10.1017/s002202990002803x.
Mammary tissue from pigs on days 60, 80, 90, 100 and 100+ (days 106-111) of pregnancy has been cultured in vitro as explants. The total accumulation in tissue and culture medium of the whey proteins alpha-lactalbumin and beta-lactoglobulin has been measured using specific radioimmunoassays. The control, uncultured tissue showed progressive morphological development from sparse, non-secretory epithelial tissue on day 60 to full lobulo-alveolar development with some accumulated secretion from day 100. In uncultured explants beta-lactoglobulin could be detected consistently from day 90 (13 +/- 12 ng/micrograms DNA, n = 4) and alpha-lactalbumin from day 100 (1.3 +/- 0.5 ng/micrograms DNA, n = 11). At all stages of pregnancy, both whey proteins increased markedly during the period of culture (up to 7 d). Stimulation of alpha-lactalbumin appeared to be primarily under prolactin control. Prolactin increased alpha-lactalbumin accumulation to a similar extent alone, or in the presence of insulin and/or corticosterone. The response to prolactin was dose-dependent over the range 0.4-20 nM (10-500 ng/ml). Porcine prolactin was more potent than ovine prolactin. There was no effect of porcine growth hormone and no synergism detected between prolactin and tri-iodothyronine. By contrast, no specific hormonal requirements were established for accumulation of beta-lactoglobulin, which appeared to increase in vitro if tissue remained viable in various combinations of insulin, corticosterone and prolactin. It was not stimulated by growth hormone. There was some indication of a prolactin-sensitive component in longer term cultures after day 4.
已将妊娠60天、80天、90天、100天及100天以上（第106 - 111天）母猪的乳腺组织作为外植体进行体外培养。使用特异性放射免疫分析法测定了乳清蛋白α-乳白蛋白和β-乳球蛋白在组织和培养基中的总积累量。未培养的对照组织显示出从第60天稀疏的非分泌性上皮组织到第100天完全的小叶-腺泡发育且有一些积累分泌物的渐进形态学发展。在未培养的外植体中，从第90天起可始终检测到β-乳球蛋白（13±12 ng/μg DNA，n = 4），从第100天起可检测到α-乳白蛋白（1.3±0.5 ng/μg DNA，n = 11）。在妊娠的所有阶段，两种乳清蛋白在培养期间（长达7天）均显著增加。α-乳白蛋白的刺激似乎主要受催乳素控制。催乳素单独或在胰岛素和/或皮质酮存在的情况下，使α-乳白蛋白积累增加到相似程度。在0.4 - 20 nM（10 - 500 ng/ml）范围内，对催乳素的反应呈剂量依赖性。猪催乳素比羊催乳素更有效。猪生长激素无作用，且未检测到催乳素与三碘甲状腺原氨酸之间的协同作用。相比之下，对于β-乳球蛋白的积累未确定特定的激素需求，如果组织在胰岛素、皮质酮和催乳素的各种组合中保持存活，β-乳球蛋白在体外似乎会增加。它不受生长激素刺激。在第4天后的长期培养中有一些迹象表明存在对催乳素敏感的成分。
