Nicholas K R, Hartmann P E
Aust J Biol Sci. 1981;34(4):435-43. doi: 10.1071/bi9810435.
The in vitro incorporation of [14c]glucose into lactose in mammary tissue, the concentration of lactose in the mammary tissue and the concentration of lactose in the mammary secretion were determined during late pregnancy and lactation in the rat. These changes were related to the decline in blood progesterone during late pregnancy. The incorporation of [14C]glucose into lactose was detected on day 20 of pregnancy; it increased gradually until day 22 and then increased rapidly just prior to term (day 23 of pregnancy) to reach mean +/- s.e.m. maximum hourly values of 12.0 +/- 1.5 cpm x 10(4)/g by day 3 of lactation, and then declined to lower values (6.1 +/- 0.6 cpm x 10(4)/g) by day 20 of lactation. The concentration of lactose in both in the mammary tissue and in the mammary secretion increased rapidly over the last 24h of pregnancy and then more gradually after birth to reach mean +/- s.e.m. maximum values of 6.85 +/- 1.11 mg/g tissues and 43.1 +/-0 2.1 g/l respectively on day 15 of lactation. The decline in plasma progesterone to low levels between days 21 and 22 of pregnancy preceded the rapid increase in the concentration of lactose in the mammary tissue. A similar relationship was observed between the decline in progesterone and the increase in lactose in mammary tissue in rats Caesarean-sectioned on day 19 of pregnancy, and the administration of progesterone immediately following Caesarean section significantly depressed the accumulation of lactose in the mammary tissue. The results support the involvement of progesterone withdrawal in lactogenesis in the rat and indicate that [14C]glucose incorporation into lactose and the concentration of lactose both in the mammary tissue and in mammary secretion are useful indicators of the synthetic activity of the mammary gland.
在大鼠妊娠后期和哺乳期，测定了乳腺组织中[14C]葡萄糖向乳糖的体外掺入、乳腺组织中乳糖的浓度以及乳腺分泌物中乳糖的浓度。这些变化与妊娠后期血液中孕酮的下降有关。在妊娠第20天检测到[14C]葡萄糖掺入乳糖；到第22天逐渐增加，然后在足月前（妊娠第23天）迅速增加，到哺乳第3天达到平均±标准误每小时最大掺入值12.0±1.5 cpm×10(4)/g，然后在哺乳第20天降至较低值（6.1±0.6 cpm×10(4)/g）。乳腺组织和乳腺分泌物中乳糖的浓度在妊娠的最后24小时迅速增加，出生后增加较为缓慢，在哺乳第1天分别达到平均±标准误最大值6.85±1.11 mg/g组织和43.1±2.1 g/l。妊娠第21天至22天血浆孕酮降至低水平先于乳腺组织中乳糖浓度的迅速增加。在妊娠第19天剖宫产的大鼠中，也观察到孕酮下降与乳腺组织中乳糖增加之间的类似关系，剖宫产术后立即给予孕酮可显著抑制乳腺组织中乳糖的积累。结果支持孕酮撤退参与大鼠的泌乳启动，并表明[14C]葡萄糖掺入乳糖以及乳腺组织和乳腺分泌物中乳糖的浓度都是乳腺合成活性的有用指标。
