Fleming J V, Barrett P, Coon S L, Klein D C, Morgan P J
Molecular Neuroendocrinology Unit, Rowett Research Institute, Bucksburn, Aberdeen, Scotland, United Kingdom.
Endocrinology. 1999 Feb;140(2):972-8. doi: 10.1210/endo.140.2.6496.
The enzyme arylalkylamine N-acetyltransferase (AANAT; EC 2.3.1.87) has been conventionally linked with the biosynthesis of melatonin within the pineal gland and retina. This study establishes that AANAT messenger RNA (mRNA) and functional enzyme occurs within the pars tuberalis (PT) and to a lesser degree within the pars distalis (PD) of the sheep pituitary gland; expression in these tissues is approximately 1/15th (PT) and 1/300th (PD) of that in the ovine pineal gland. AANAT mRNA in the PT appears to be expressed in the same cells as the Mel1a receptor. No evidence was obtained to indicate that either PT or PD cells have the ability to synthesize melatonin, suggesting that this enzyme plays a different functional role in the pituitary. We also found that cAMP regulation of the abundance of AANAT mRNA differs between the PT and pineal gland. Forskolin (10 microM) has no effect on pineal AANAT mRNA levels, yet represses expression in the PT. This suppressive influence could be mediated by ICER (inducible cAMP response early repressor), which is induced by forskolin in both tissues. Although it appears that the specific function and regulation of AANAT in the pituitary gland differ from that in the pineal gland, it seems likely that AANAT may play a role in the broader area of signal transduction through the biotransformation of amines.
芳基烷基胺N - 乙酰基转移酶（AANAT；EC 2.3.1.87）传统上被认为与松果体和视网膜中褪黑素的生物合成有关。本研究证实，AANAT信使核糖核酸（mRNA）和功能性酶存在于绵羊垂体的结节部（PT），在远侧部（PD）中的含量较少；这些组织中的表达量约为绵羊松果体中的1/15（PT）和1/300（PD）。PT中的AANAT mRNA似乎与Mel1a受体在相同细胞中表达。没有证据表明PT或PD细胞具有合成褪黑素的能力，这表明该酶在垂体中发挥不同的功能作用。我们还发现，PT和松果体中cAMP对AANAT mRNA丰度的调节有所不同。福斯高林（10微摩尔）对松果体AANAT mRNA水平没有影响，但会抑制PT中的表达。这种抑制作用可能由ICER（诱导型cAMP反应早期阻遏物）介导，福斯高林在这两种组织中均可诱导其产生。尽管垂体中AANAT的特定功能和调节似乎与松果体不同，但AANAT很可能通过胺的生物转化在更广泛的信号转导领域发挥作用。
