Molecular biological study on the melatonin synthesis during the transformation from photoreceptor cells to endocrine cells

哺乳动物松果体细胞群体内的同质性一直被讨论。几项松果体研究表明，羟吲哚o -甲基转移酶（HIOMT）、视网膜s抗原和神经元特异性烯醇化酶（NSE）的定位是可变的。然而，在以往描述形态异质性的研究中，除了相邻松果体细胞之间的差异外，没有提到细胞群的具体分布。在本研究中，我们利用NSE、synaptophysin（SY-38）和HIOMT抗体作为松果体细胞的标记物，以及胶质纤维酸性蛋白（GFAP）作为间质细胞的标记物，证明了牛松果体实质细胞的皮质和髓质排列。每一种抗原的免疫反应性松果体细胞在皮层的分布比在髓质的分布更密集。在皮层中，gfap阳性的间质细胞有大的、染色强烈的胞体，具有几个长细胞质突起，而在髓质中，它们较小，标记不强烈，从核周中出现了许多精细的短突起。此外，通过HIOMT mRNA特异性探针，我们研究了皮层和髓质之间褪黑素代谢活性的可能差异。利用激光共聚焦显微镜和原位杂交技术对HIOMT mRNA进行分析发现，mRNA转录本在皮层中的表达比在髓质中的表达更强烈。我们的研究结果表明，皮层中的松果体细胞比髓质中的松果体细胞更像分泌细胞。

Homogeneity within populations of mammalian pinealocytes has long been discussed. Several pineal studies have shown the variable localization of hydroxyindole O-methyltransferase(HIOMT), retinal S-antigen, and neuron-specific enolase(NSE). However, in the previous studies describing morphological heterogeneity, no stecific distributions of cell groups are mentioned, with the exception of variations among neighboring pinealocytes.In the present study, we demonstrated a cortical and medullary arrangement of parenchymal cells in the bovine pineal gland by using antibodies for NSE, synaptophysin(SY-38), and HIOMT as markers of pinealocytes, and glial fibrillary acidic protein(GFAP) as a marker of interstitial cells. Immunoreactive pinealocytes of each antigen examined were more densely distributed in the cortex than in the medulla. In the cortex, GFAP-positive interstitial cells had large intensely-stained soma endowed with several long cytoplasmic processes, whereas in the medulla, they smaller, less intensely labeled perikarya from which numbers of fine short processes emerged. Furthermore, by means of probes specific for HIOMT mRNA, we examined possible differences in melatonin metabolic activity between the cortex and the medulla. An analysis using confocal laser microscopy together with in situ hybridization for HIOMT mRNA showed that the expression of mRNA transcripts in the cortex was more intense than that in the medulla. Our results suggest that the pinealocytes in the cortex are more secretory-like elements than those in the medulla.