Cristina Carolina, Díaz-Torga Graciela, Góngora Adrián, Guida Maria Clara, Perez-Millán Maria Inés, Baldi Alberto, Becu-Villalobos Damasia
Instituto de Biología y Medicina Experimental, CONICET, V Obligado 2490, 1428, Buenos Aires, Argentina.
Am J Physiol Endocrinol Metab. 2007 Nov;293(5):E1341-51. doi: 10.1152/ajpendo.00260.2007. Epub 2007 Sep 11.
Dopamine D2 receptor (D2R) knockout (KO) female mice develop chronic hyperprolactinemia and pituitary hyperplasia. Our objective was to study the expression of the mitogen fibroblast growth factor (FGF2) and its receptor, FGFR1, comparatively in pituitaries from KO and wild-type (WT) female mice. We also evaluated FGF2 subcellular localization and FGF2 effects on pituitary function. FGF2-induced prolactin release showed a similar response pattern in both genotypes, even though basal and FGF2-stimulated release was higher in KO. FGF2 stimulated pituitary cellular proliferation (MTS assay and [(3)H]thymidine incorporation), with no differences between genotypes. FGF2 concentration (measured by ELISA) in whole pituitaries or cultured cells was lower in KO (P < 0.00001 and 0.00014). Immunofluorescence histochemistry showed less FGF2 in pituitaries from KO females and revealed a distinct FGF2 localization pattern between genotypes, being predominantly nuclear in KO and cytosolic in WT pituitaries. Finally, FGF2 could not be detected in the conditioned media from pituitary cultures of both genotypes. FGFR1 levels (Western blot and immunohistochemistry) were higher in pituitaries of KO. Basal concentration of phosphorylated ERKs was lower in KO cells (P = 0.018). However, when stimulated with FGF2, a significantly higher increment of ERK phosphorylation was evidenced in KO cells (P < or = 0.02). We conclude that disruption of the D2R caused an overall decrease in pituitary FGF2 levels, with an increased distribution in the nucleus, and increased FGFR1 levels. These results are important in the search for reliable prognostic indicators for patients with pituitary dopamine-resistant prolactinomas, which will make tumor-specific therapy possible.
多巴胺D2受体（D2R）基因敲除（KO）雌性小鼠会出现慢性高催乳素血症和垂体增生。我们的目的是比较研究KO和野生型（WT）雌性小鼠垂体中促有丝分裂成纤维细胞生长因子（FGF2）及其受体FGFR1的表达。我们还评估了FGF2的亚细胞定位以及FGF2对垂体功能的影响。FGF2诱导的催乳素释放在两种基因型中显示出相似的反应模式，尽管KO小鼠的基础释放量和FGF2刺激后的释放量更高。FGF2刺激垂体细胞增殖（MTS试验和[³H]胸腺嘧啶核苷掺入），基因型之间无差异。KO小鼠全垂体或培养细胞中的FGF2浓度（通过ELISA测量）较低（P < 0.00001和0.00014）。免疫荧光组织化学显示，KO雌性小鼠垂体中的FGF2较少，并且揭示了基因型之间不同的FGF2定位模式，在KO小鼠中主要位于细胞核，而在WT小鼠垂体中主要位于细胞质。最后，在两种基因型的垂体培养条件培养基中均未检测到FGF2。KO小鼠垂体中的FGFR1水平（蛋白质印迹法和免疫组织化学）较高。KO细胞中磷酸化ERK的基础浓度较低（P = 0.018）。然而，当用FGF2刺激时，KO细胞中ERK磷酸化的增加明显更高（P≤0.02）。我们得出结论，D2R的破坏导致垂体FGF2水平总体下降，在细胞核中的分布增加，以及FGFR1水平增加。这些结果对于寻找垂体多巴胺抵抗性催乳素瘤患者的可靠预后指标很重要，这将使肿瘤特异性治疗成为可能。
