Schussler N, Bayet M C, Frain O, Peillon F, Biguet N F
INSERM U223, Paris, France.
Biochem Biophys Res Commun. 1992 Dec 30;189(3):1716-24. doi: 10.1016/0006-291x(92)90276-q.
The anterior pituitary is thought to be unable to synthesize dopamine (DA) except under experimental conditions where a tyrosine hydroxylase (TH) activity, the rate-limiting step of its synthesis, has been demonstrated. In this work, we tested whether the enzyme described as active under particular conditions comes from de novo TH gene transcription or from a pre-existing TH mRNA poorly translated or untranslated under physiological conditions. Therefore, we searched for the presence of TH mRNA in normal female rat pituitary using the polymerase chain reaction following reverse transcription (RT/PCR) and in situ hybridization (ISH). The neurointermediate lobe (NIL) of the hypophysis was used as negative tissue, since it is thought to be unable to synthesize TH. As expected, no ISH labelling could be seen in the neural lobe (NL). However, scarce labelled cells were found in the intermediate lobe (IL) confirming the positive results observed in the NIL by RT/PCR. The anterior lobe (AL) also presented TH mRNA by PCR and ISH. The TH gene expression in sparse cells of the AL is discussed in regard to the ability of the AL to synthesize DA under particular conditions from a pre-existing mRNA.
除了在实验条件下，即已证明酪氨酸羟化酶（TH）活性（其合成的限速步骤）存在时，垂体前叶被认为无法合成多巴胺（DA）。在这项研究中，我们测试了在特定条件下被描述为有活性的这种酶是来自TH基因的从头转录，还是来自在生理条件下翻译不良或未翻译的预先存在的TH mRNA。因此，我们使用逆转录后的聚合酶链反应（RT/PCR）和原位杂交（ISH），在正常雌性大鼠垂体中寻找TH mRNA的存在。垂体的神经中间叶（NIL）被用作阴性组织，因为它被认为无法合成TH。正如预期的那样，在神经叶（NL）中未观察到ISH标记。然而，在中间叶（IL）中发现了少量标记细胞，这证实了RT/PCR在NIL中观察到的阳性结果。前叶（AL）通过PCR和ISH也呈现出TH mRNA。关于AL在特定条件下从预先存在的mRNA合成DA的能力，讨论了AL中稀疏细胞中的TH基因表达。
