Kishi K, Kobayashi F
Biol Reprod. 1984 May;30(4):879-85. doi: 10.1095/biolreprod30.4.879.
The present study investigated whether prolactin (Prl) itself acts as a physiological factor in the control of nocturnal Prl surges in pseudopregnant (PSP) rats. Intracerebroventricular (ICV) injection of ovine Prl at doses of 0.1, 1 and 10 micrograms/rat given 1 h before the start of the nocturnal Prl surge inhibited its occurrence completely and dose-dependently. The same inhibition of nocturnal Prl surge was observed 4 and 1 h before, and even 1.5 h after, the start of the nocturnal Prl surge. Prl concentrations in the cerebrospinal fluid (CSF) increased twice a day, the timings of which were similar to those of diurnal and nocturnal surges of Prl in PSP rats. Changes of Prl concentrations in the CSF correlated closely with those of plasma Prl concentrations. ICV injection of antiserum to rat Prl in the first half period of nocturnal Prl surges did not modify the elevation pattern of plasma Prl concentrations. Inhibition of nocturnal Prl surge produced by ICV injection of ovine Prl was overcome by subcutaneous administration of pimozide (1 mg/kg). These results suggest that Prl itself may act as an important physiological modulatory factor in the control mechanism(s) of nocturnal Prl surge in PSP rats. Prl may inhibit further discharge of Prl by a feedback mechanism through the hypothalamic dopaminergic system within a very short time period.
本研究调查了催乳素（Prl）自身是否作为一种生理因素参与假孕（PSP）大鼠夜间Prl分泌高峰的调控。在夜间Prl分泌高峰开始前1小时，向大鼠脑室内（ICV）注射剂量为0.1、1和10微克/只的羊Prl，可完全抑制其出现，且呈剂量依赖性。在夜间Prl分泌高峰开始前4小时、1小时，甚至开始后1.5小时，均观察到对夜间Prl分泌高峰的相同抑制作用。脑脊液（CSF）中的Prl浓度一天升高两次，其时间与PSP大鼠Prl的昼夜分泌高峰时间相似。CSF中Prl浓度的变化与血浆Prl浓度的变化密切相关。在夜间Prl分泌高峰的前半期向大鼠脑室内注射抗大鼠Prl血清，并未改变血浆Prl浓度的升高模式。皮下注射匹莫齐特（1毫克/千克）可克服脑室内注射羊Prl对夜间Prl分泌高峰的抑制作用。这些结果表明，Prl自身可能作为一种重要的生理调节因子参与PSP大鼠夜间Prl分泌高峰的调控机制。Prl可能通过下丘脑多巴胺能系统在极短时间内通过反馈机制抑制Prl的进一步释放。
