Xu M, Proudman J A, Pitts G R, Wong E A, Foster D N, el Halawani M E
Department of Animal Science, University of Minnesota, St. Paul 55108, USA.
Proc Soc Exp Biol Med. 1996 May;212(1):52-62. doi: 10.3181/00379727-212-43991.
It is well documented that vasoactive intestinal peptide (VIP) is a prolactin (PRL)-releasing factor and that dopamine (DA) is an inhibitory neurotransmitter in avian species. However, the roles of VIP and DA in the regulation of PRL gene expression are unclear. In this study, primary anterior pituitary cells cultured from laying turkeys were utilized to investigate the influence of VIP and dopaminergic D1 and D2 receptors on PRL secretion, PRL mRNA, and PRL synthesis. Incubation of pituitary cells with VIP increased PRL secretion up to 3.5-fold within 3 hr. Prolactin mRNA was undetectable during the first 2 hr of pituitary cell treatment; thereafter, the PRL mRNA content response to VIP increased with 24-48 h (P < 0.05). Total PRL content (media + cellular) increased over time in the presence of VIP. The response of cells incubated in the presence of a dopaminergic D1 receptor agonist (SKF38393) was variable and inconclusive. However, cells incubated with a dopaminergic D2 receptor agonist (quinpirole) inhibited VIP-induced PRL secretion (P < 0.05) and PRL mRNA levels (P < 0.05) in a dose-related fashion without effect on the basal levels of PRL release and PRL mRNA. These observations suggest that VIP, in addition to acting as a PRL-releasing peptide, also plays a role in the regulation of PRL gene expression. Moreover, the results of this study also indicate that a drug that can selectively stimulate dopamine D2 receptors can also regulate PRL secretion and PRL mRNA in turkey pituitary cells in culture.
有充分的文献记载，血管活性肠肽（VIP）是一种催乳素（PRL）释放因子，而多巴胺（DA）是禽类中的一种抑制性神经递质。然而，VIP和DA在PRL基因表达调控中的作用尚不清楚。在本研究中，利用从产蛋火鸡培养的原代垂体前叶细胞来研究VIP以及多巴胺能D1和D2受体对PRL分泌、PRL mRNA和PRL合成的影响。垂体细胞与VIP孵育3小时内可使PRL分泌增加至3.5倍。在垂体细胞处理的最初2小时内未检测到催乳素mRNA；此后，PRL mRNA含量对VIP的反应在24 - 48小时内增加（P < 0.05）。在有VIP存在的情况下，总PRL含量（培养基 + 细胞）随时间增加。在多巴胺能D1受体激动剂（SKF38393）存在下孵育的细胞反应多变且无定论。然而，用多巴胺能D2受体激动剂（喹吡罗）孵育的细胞以剂量相关方式抑制VIP诱导的PRL分泌（P < 0.05）和PRL mRNA水平（P < 0.05），而对PRL释放和PRL mRNA的基础水平无影响。这些观察结果表明，VIP除了作为一种PRL释放肽发挥作用外，在PRL基因表达调控中也起作用。此外，本研究结果还表明，一种能选择性刺激多巴胺D2受体的药物也可调节培养的火鸡垂体细胞中的PRL分泌和PRL mRNA。
