Mattheij J A, Swarts H J, Verstijnen C P
Horm Res. 1984;20(4):261-8. doi: 10.1159/000180006.
In dams which had been kept isolated from pups for 8-10 h, the magnitude of the suckling-induced prolactin rise in the plasma was studied in relation to intensity of suckling stimulus and lactational age of the mother. At midlactation the response of prolactin evoked by suckling was enhanced as litter size increased. Suckling of 2 pups induced a greater prolactin rise in dams adjusted to 2 pups than in dams adjusted to 8 pups. Suckling of 8 pups caused a greater prolactin rise in dams which had been adjusted to an 8-pup litter, than in rats with a 2-pup litter. At late and prolonged lactation the rise of prolactin in the plasma induced by the suckling stimulus of 8 pups was significantly lower than at midlactation. Injection of perphenazine after a period of suckling induced a moderate increase of plasma prolactin in dams at midlactation, and a similar increase in dams at late lactation and at day 42 of lactation. It is concluded that in the first half of lactation the number of pups, i.e. the intensity of the suckling stimulus, is an important factor in determining the magnitude of the prolactin response to suckling. The lower response of plasma prolactin to suckling in late lactation is neither caused by a decrease in suckling stimulus from the pups nor by an increase in prolactin clearance; it is probably due to a gradual reduction in prolactin synthesizing and releasing capacity of the pituitary, brought on by a desensitization of the neural or neuroendocrine system to suckling stimuli as lactation proceeds.
在与幼崽隔离8 - 10小时的母鼠中，研究了哺乳诱导的血浆催乳素升高幅度与哺乳刺激强度及母鼠泌乳期的关系。在泌乳中期，随着窝仔数增加，哺乳诱发的催乳素反应增强。与适应8只幼崽的母鼠相比，2只幼崽的哺乳在适应2只幼崽的母鼠中诱导出更大的催乳素升高。8只幼崽的哺乳在适应8只幼崽窝仔数的母鼠中引起的催乳素升高，比在2只幼崽窝仔数的大鼠中更大。在泌乳后期和延长泌乳期，8只幼崽的哺乳刺激诱导的血浆催乳素升高明显低于泌乳中期。在一段时间的哺乳后注射奋乃静，在泌乳中期的母鼠中诱导血浆催乳素适度增加，在泌乳后期和泌乳第42天的母鼠中也有类似增加。得出的结论是，在泌乳的前半期，幼崽数量即哺乳刺激强度，是决定催乳素对哺乳反应幅度的一个重要因素。泌乳后期血浆催乳素对哺乳的较低反应，既不是由于幼崽哺乳刺激的减少，也不是由于催乳素清除率的增加；这可能是由于随着泌乳的进行，神经或神经内分泌系统对哺乳刺激脱敏，导致垂体催乳素合成和释放能力逐渐降低。
