Yuan Zung Fan, Yang Shu-Chuan, Pan Jenn-Tser
Department of Physiology, National Yang-Ming University, Taipei, Taiwan.
J Biomed Sci. 2002 Mar-Apr;9(2):112-8. doi: 10.1007/BF02256021.
Both systemic and central effects of a newly discovered prolactin (PRL)-releasing factor (PRF), prolactin-releasing peptide (PrRP), were determined in this study. Systemic injection of PrRP (1 and 10 microg/rat, i.v.) stimulated PRL secretion in ovariectomized, estrogen-treated rats similar to the effect of another PRF, thyrotropin-releasing hormone (TRH). Pretreatment with a dopamine D2 receptor antagonist, sulpiride (1 microg/rat, i.v.), potentiated the stimulatory effect of both PrRP and TRH on PRL secretion. Using the double-labeling immunohistochemical method, PrRP-immunoreactive terminals were found in close contact with tyrosine-hydroxylase-immunoreactive neurons in the hypothalamic arcuate nucleus. Central administration of PrRP (0.1-1,000 ng/rat, i.c.v.) stimulated tuberoinfundibular but not nigrostriatal dopaminergic neuronal activity in 15 min. Levels of 3,4-dihydroxyphenylacetic acid (DOPAC) in the median eminence and striatum were used as indices for tuberoinfundibular dopaminergic (TIDA) and nigrostriatal dopaminergic neuronal activities, respectively. The serum PRL level, however, was not significantly changed. Similar treatment with TRH (10 ng/rat, i.c.v.) stimulated and inhibited TIDA neuronal activity and serum PRL, respectively, at 30 min. In summary, PrRP may play a role in both the central and peripheral control of PRL secretion.
本研究确定了新发现的催乳素（PRL）释放因子（PRF）——催乳素释放肽（PrRP）的全身和中枢效应。静脉注射PrRP（1和10微克/大鼠）可刺激去卵巢、雌激素处理大鼠的PRL分泌，其作用类似于另一种PRF——促甲状腺激素释放激素（TRH）。用多巴胺D2受体拮抗剂舒必利（1微克/大鼠，静脉注射）预处理可增强PrRP和TRH对PRL分泌的刺激作用。采用双标免疫组织化学方法，发现PrRP免疫反应性终末与下丘脑弓状核中酪氨酸羟化酶免疫反应性神经元紧密接触。脑室内注射PrRP（0.1 - 1000纳克/大鼠）可在15分钟内刺激结节漏斗部而非黑质纹状体多巴胺能神经元活动。分别以正中隆起和纹状体中3,4 - 二羟基苯乙酸（DOPAC）水平作为结节漏斗部多巴胺能（TIDA）和黑质纹状体多巴胺能神经元活动的指标。然而，血清PRL水平没有显著变化。脑室内注射TRH（10纳克/大鼠）在30分钟时分别刺激和抑制了TIDA神经元活动及血清PRL。总之，PrRP可能在PRL分泌的中枢和外周调控中均发挥作用。
