Niimi M, Takahara J, Sato M, Murao K, Kawanishi K
Department of Clinical Laboratory, Kagawa Medical School, Japan.
Life Sci. 1993;53(4):305-13. doi: 10.1016/0024-3205(93)90749-s.
Recent findings indicate that low concentrations of dopamine (DA) stimulate the secretion of prolactin (PRL) in vitro. In this study, we found that low concentrations of the highly-specific DA D2 receptor agonist, quinpirole hydrochloride (LY) stimulate PRL secretion in female rats, assessed by reverse hemolytic plaque assay. Low concentrations of LY (10(-12), 10(-10) M) increased the mean plaque area and increased the fraction of lactotrophs forming large plaques. On the other hand, higher concentrations of LY (10(-8), 10(-6) M) reduced the mean plaque size. Treatment of cells with 10(-6) M LY produced a unimodal distribution of small plaques. Low concentrations of LY (10(-12), 10(-10) M) with TRH (10(-7) M) produced an additive effect on TRH-induced PRL release. Pretreatment of anterior pituitary cells with pertussis toxin (30 ng/ml, 24 h) inhibited the LY-stimulated increase in plaque area. These findings indicate that very low concentrations of DA agonist stimulate the secretion of PRL per cell, and that the stimulatory effects of DA agonist on PRL secretion may be mediated by a pertussis toxin-sensitive G protein.
最近的研究结果表明，低浓度多巴胺（DA）在体外可刺激催乳素（PRL）的分泌。在本研究中，我们发现，通过反向溶血空斑试验评估，低浓度的高特异性DA D2受体激动剂盐酸喹吡罗（LY）可刺激雌性大鼠PRL的分泌。低浓度的LY（10⁻¹²、10⁻¹⁰ M）可增加平均空斑面积，并增加形成大空斑的催乳细胞比例。另一方面，较高浓度的LY（10⁻⁸、10⁻⁶ M）可减小平均空斑大小。用10⁻⁶ M LY处理细胞可产生小空斑的单峰分布。低浓度的LY（10⁻¹²、10⁻¹⁰ M）与促甲状腺激素释放激素（TRH，10⁻⁷ M）联合使用，对TRH诱导的PRL释放产生相加效应。用百日咳毒素（30 ng/ml，24小时）预处理垂体前叶细胞可抑制LY刺激的空斑面积增加。这些发现表明，极低浓度的DA激动剂可刺激单个细胞PRL的分泌，且DA激动剂对PRL分泌的刺激作用可能由百日咳毒素敏感的G蛋白介导。
